Practitionersâ&#x20AC;&#x2122; Guide Book on the Best Agricultural Practices for Drought and Floods in Sri Lanka
Department of Agriculture, Sri Lanka (DOA) Sri Lanka Council for Agricultural Research Policy (SLCARP) Disaster Management Centre, Sri Lanka (DMC) United Nations Development Programme, Sri Lanka (UNDP) International Water Management Institute (IWMI)
Practitioners’ Guide Book on the Best Agricultural Practices for Drought and Floods in Sri Lanka Copyright © UNDP  All Rights Reserved Manufactured in Sri Lanka ISBN: 978-955-9224-41-9 The views expressed in this publication are those of the authors/technical contributors and not necessarily those of the United Nations Development Programme (UNDP) Published by: Department of Agriculture, 2011
Guide Book Development Team Technical Contribution Dr. D.L. Amarasinghe Mr. B.R. Ariyaratne Dr. Jinadari De Zoysa Dr. Nimal Dissanayake Dr. C. Kudagamage Dr. B.V.R. Punyawardena Dr. Ajantha De Silva Dr. W.M.A.D.B. Wickramasinghe Dr. P.B. Dharmasena
Graphics and Presentation Design Dr. Rohan Wijekoon Concept and Coordination Dr. Ananda Mallawatantri (UNDP) Mr. U.W.L. Chandradasa (DMC) Mr. Ramitha Wijethunga (UNDP) Mr. Suranga Kahandawa (UNDP) Mr. A.G.C. Janaka Gamage (UNDP) Ms. S.M.P. Chandra Padmini (SLCARP) Graphic Designs Ms. K.K.G.K.K.K. Kannangara (Audio Visual Centre (AVC) of DOA) Mr. Milton Gunasena (AVC) Mr. A.C. Udayasiri (AVC) Mr. D.M. Amaradasa (AVC) Ms. Rasika Akalanka Akuramboda (AVC) Ms. Gayani Dilrukshi Eriyagama (AVC) Ms. M.K.D.M. Shriyantha Menike (AVC)
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Chapter 1 CLIMATE, DROUGHT AND FLOOD IN SRI LANKA
Chapter 2 CLIMATE AND SOILS OF DIVISIONAL SECRETARIAT AREAS
Chapter 3 CULTIVATION DECISION MAKING
Chapter 4 BEST CROP MANAGEMENT PRACTICES FOR DROUGHT BEFORE CULTIVATION
Chapter 5 BEST CROP MANAGEMENT PRACTICES FOR DROUGHT
Chapter 6 BEST CROP MANAGEMENT PRACTICES FOR FLOOD
Chapter 7 MANAGEMENT OF LAND AND WATER RESOURCES TO REDUCE EFFECTS OF DROUGHT AND FLOOD AT VILLAGE LEVEL
Chapter 8 INDIGENOUS TECHNOLOGY TO MITIGATE THE RISK OF DROUGHT AND FLOOD
Annex SOIL SERIES, ASSOCIATIONS AND COMPLEXES FOUND IN DIFFERENT DISTRICTS
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Message from Minister of Agriculture I have pleasure and honour in sending this message on the occasion of the launch of the Practitionersâ&#x20AC;&#x2122; Guide Book on the Best Agricultural Practices on Drought and Floods in Sri Lanka. Global trends have shown increasing tendencies of natural disasters over the past two decades in Sri Lanka and the predictions are such that climate change impacts will further aggravate this situation. Poor farmers in rural areas as well as the consumers in the urban areas suffer lot due to the crop losses in the drought and flood. In order to address this complex scenario, a sound disaster risk reduction program based on public policy directives, community awareness and active participation, relevant research and development and multi stakeholder cooperation and coordination are critically important. I appreciate the timely intervention of Sri Lanka Council for Agricultural Research, Disaster Management Centre and UNDP in bringing the senior expert scientists to develop this valuable document. It is our challenge to make use of this valuable information in decision making, planning and mainstreaming disaster management in the agriculture sector. I also extend my sincere appreciation to the senior scientific team who collaborate and share their valuable experience and knowledge in the agricultural field to protect our nation. This document will go a long way in protecting our farmers and consumers from the ill effects of climate change. Due to lack of knowledge and awareness on disasters, heavy crop losses have occurred in this year and the vegetable prices have sky rocketed. To prevent this skewed situation appropriate strategic plans have to be developed to minimize crop losses. Short duration crop varieties must be introduced to rain fed farmers and research should be conducted to innovate those varieties. Best crop management methods should be practiced such as shelter houses, micro irrigation methods, rain water harvesting methods etc. Availability and access to appropriate information on disaster risk reduction is important for sustainable development in agriculture. Sharing of information on laboratory and field research, studies on vulnerability, technologies, mitigation measures etc., provides the scientific base and strengths risk reduction initiatives. I congratulate all the scientists, the coordinating team and heads of the institutes on their great achievement.
Mahinda Yapa Abeywardena Minister of Agriculture
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CHAPTER - 1
CLIMATE, DROUGHT AND FLOOD IN SRI LANKA - -
ri Lanka has endowed with a considerable wealth of natural resources and water is one of the most important resources found in abundance. However, the availability of the water resource can greatly vary in terms of its spatial and temporal distribution of rainfall. High variability of rainfall could lead to catastrophic events resulting prolonged droughts and devastating floods. The average annual rainfall of the island varies from 900mm (Maha Lewaya, Hambantota) to 5,500mm (Kenilworth Estate, Ginigathhena).
Rainfall and growing seasons Rainfall seasons
Annual rainfall pattern in Sri Lanka is characterized by four distinct rainfall seasons, viz. South West Monsoon, North East Monsoon and two Inter monsoonal periods.
The South West Monsoon (SWM) brings heavy rains to the western and southwestern slopes of the central highlands and to a lesser degree in adjoining lowlands in West, South, and Southwest during the months from June to September.
The North East Monsoon (NEM) brings fair amount of rains to the eastern side of the central hills, adjoining lowlands and to a lesser degree in Northern parts of the Island during the months in January and February. - -
Day time heating of the land and evening thunder showers during inter-monsoons
During inter-monsoonal months (March-April and October-November), the Island receives heavy rains due to convectional activity and frequent formation of weather systems (Low-level atmospheric disturbances, depressions and cyclonic storms), especially during October and November. Out of these four inter-monsoonal months, the first two are referred as the “First inter-monsoon (FIM)” while the last two months as the “Second inter-monsoon (SIM)”.
Climatic year/ Hydrological year Detailed studies on climatology of Sri Lanka has identified that “climatic year” or “hydrological year” of the Island begins in March and not in January. The four rainfall seasons do not bring homogeneous rainfall regimes over the whole Island and it is the main cause to exhibit such a high agro-ecological diversity of the country despite its relatively small aerial extent. Of the four rainfall seasons, two consecutive rainy seasons make up the major growing seasons of Sri Lanka, namely Yala and Maha seasons. Generally Yala season is the combination of FIM and SWM rains. However, since SWM rains are not effective over the Dry zone it is only the FIM rains that fall during the Yala season in the Dry zone from mid March to early May. Being effective rains are received only for two months, the Yala season is considered as the minor growing season of the Dry zone. The major growing season of the whole country, Maha, begins with arrival of the SIM rains in Mid September/ October and continues up to late January/ early February with the NEM rains. - -
Drought in general Drought is a normal recurring feature of climate. It occurs virtually in all-climatic regions in the world including high as well as low rainfall areas. It is a temporary aberration of weather, in contrast to aridity, which is a permanent feature of climate and is restricted to low rainfall areas. Drought is a consequence of a natural reduction in the amount of precipitation received over an extended period of time, usually associated with high temperatures, comparatively fast winds, and low relative humidity. Droughts or crop water stress exists when the ratio of actual evapo-transpiration to potential evapo-transpiration falls below one. Drought differs from other natural hazards in several ways. First, the absence of a precise and universally accepted definition of drought adds to the confusion that whether a drought really exists and, if it does, its degree of severity. Realistically, definitions of drought must be region and application (or impact) specific. This is one reason as to why the scores of definitions for drought exist. Second, the impacts of drought often accumulate slowly over a considerable period of time and may linger for seasons or years after the termination of the event. Moreover, the onset and end of drought is difficult to determine. Because of these reasons, drought is often referred to as a creeping phenomenon. Third, drought impacts are nonstructural, in contrast to the impacts of floods, landslides, cyclones, and most other natural hazards. Its impacts are spread over a larger geographical area than the damages that result from other natural hazards. For these reasons, the quantification of impacts and the provision of disaster relief are far more difficult tasks for drought than they are for other natural hazards. Even though it is a natural event, in reality, the risk associated with drought for any region is a product of both the regionâ&#x20AC;&#x2122;s exposure to the event (i.e., probability of occurrence at various severity levels) and the vulnerability of society to the event. However, vulnerability on the other hand
Structural damage caused by Tsunami
is, determined by social factors such as population, demographic characteristics, technology, policies, social behavior, land use patterns, water use, economic development, diversity of economic base, and cultural composition. These factors change over time, so vulnerability will change in response to these changes. Consequently droughts Structural damage that follow up after initial droughts caused by Earth slip in the same region will have different effects, even if they are identical in intensity, duration, and spatial characteristics with the initial droughts, because societal characteristics may have changed. Therefore, identification of factors that explain who and what is at risk and why (i.e., the underlying factors behind the vulnerability) can lead to the development and implementation of a wide variety of mitigation actions and programs to reduce impacts from future drought events.
Droughts in Sri Lanka Under a changing and variable climate, the risk of drought is increasing worldwide and Sri Lanka is no exception. Thus, Disaster Management Act No. 13, 2005 of Government of Sri Lanka has identified drought as one among the 21 natural or man-made disasters observed in the Island. Drought or extreme negative rainfall anomalies are experienced in Sri Lanka under two major meteorological situations.
1. One situation arises when the air stream over the island comes from Northern hemisphere high-pressure system that travels over the dry mainland of India immediately before reaching Sri Lanka in Northeast monsoon season during December to February.
2. Marked decrease in formation of weather systems (low-level disturbances, depressions and cyclonic storms) in the Bay of Bengal also creates below normal rainfall during October to January. Such droughts and dry spells can affect most regions of the Island. Rains during mid March to early May, generally, occur due to convection under local thermal conditions and influence of the InterTropical Convergence zone (ITCZ). However, activity of the ITCZ during this period is highly variable and thus, it is common to experience below normal rainfall in most regions of the country, especially in the Dry zone.
3. The third situation may occur during the Southwest monsoon months of May to September when the prevailing air stream of the monsoon is relatively dry due to deviation of flow direction from its usual path. Under such situations, dry conditions are likely to occur in districts that lie across the Wet and Intermediate zones. Thus, it is apparent that almost all locations of the Island have a potential vulnerability to experience drought. Historical and legendary accounts show that even the countryâ&#x20AC;&#x2122;s wettest region, Southwestern part of the central hills has had severe droughts in the past. - -
Spatial and temporal variations of droughts in Sri Lanka Characteristics of the temporal variations of monthly rainfall is very important to describe the nature of droughts in Sri Lanka (Map 1). Droughts are generally absent during the period from October to December. This period is the main storm season in Sri Lanka attributed to frequent formation of low-level disturbances and depressions in Bay of Bengal. All the remaining months except April, however, are characterized by droughts in certain areas of Sri Lanka at particular times. It is apparent that intensity, duration and frequency of droughts in Sri Lanka increase away from the southwestern part of the island towards north, northeast, northwest and southeast. It is due to the fact that rains from southwest monsoon wind stream are generally restricted to the south western regions of the country.
Map 1: Spatial pattern of the drought severity during Yala and Maha seasons in Sri Lanka.
Source: NRMC /DOA.
Impacts of droughts on agriculture and livelihood Impact of droughts on agriculture is apperant in all climatic zones, but its characteristics vary significantly from one region to another. The following sections will deal as to how the droughts would affect the agriculture and livelihood in Sri Lanka.
1. Impacts due to soil moisture stress Crops need ample amount of soil moisture throughout the growing season to obtain high yields and high crop quality. All crops, particularly perennial crops, will get off to a better start early in the season if the root zone soil moisture is brought up to the field capacity. When the soil is wet, water has a high potential energy and hence it is relatively free to move and easily taken up by the plant roots.
In dry soils which occur under drought conditions, the water has a low potential energy and consequently it is strongly bounded by capillary and absorptive forces to the soil matrix, and is less easily extracted by the crop. When the potential energy of the soil water drops below a threshold value, the crop is said to be water stressed.
Meanwhile, under drought conditions, evapotranspiration losses are extremely high due to increased atmospheric demand for water and thus, it will further aggravate the water stress conditions.
The main consequence of moisture stress is decreased plant growth and development caused by reduced photosynthesis. Photosynthesis is the process in which plants combine water and carbon dioxide to synthesize carbohydrates using sunlight as the energy source.
Open stomates in normal weather
Closed stomates in drought
When stomates are closed as a self-protective mechanism of the plant for water stress, the plant wilts, carbon dioxide from the atmosphere cannot enter the leaf and hence, photosynthesis is reduced or stopped with subsequent decreased growth and development. This will lead to crop growth retardation, yield reduction and even complete crop failures if the situation is not corrected. During drought conditions, especially in tropical countries like Sri Lanka, ambient temperature is significantly higher than that of a normal wet season. Under such situation, crops will have higher vulnerability to pest infestation due to several reasons. Higher temperature regimes during drought conditions will have a shorter life cycle of insect pests with a fast growth rate resulting higher pest population in a given time. Meanwhile, water stress-plants that are grown under drought conditions tend to secrete metabolic compounds with high sugar contents. It will attract more insect pests resulting enhanced pest attacks than that of a normal season.
Higher vulnerability to pest during drought Shorter life cycle of pest in drought
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However, the degree of damage to the crops caused by the drought depends on the stage of crop development at which it occurs. It can be summarized under following three stages of crop development. 1. Effect of delayed rain and early season drought 2. Effect of mid season drought 3. Effect of late season and terminal drought
Effect of delayed rains and early season droughts Following impacts are possible due to drought conditions that may occur due to delay in onset of rains in the growing season or drought conditions in the early stages of the season. Delay in field operations Delay in sowing or untimely sowing of seeds Poor germination Low crop stand Weak seedlings Increased susceptibility to pests
Effect of mid-season droughts This is the vegetative phase of the crop growth. The most obvious effect of water stress attributed to drought conditions during this period is the reduced leaf expansion. Visible injury of water stress is seen in the form of wilting. Paleness and dryness of leaves is also seen in prolonged drought conditions. Leaf abscission is often noticed due to the accumulation of Abscissic acid under prolonged drought conditions. Reduced growth of crops can also be seen due to the reduction in cell volume and water potential. In addition, poor seed/ pod/ fruit settings will also be observed.
Effect of late season or terminal droughts Following impacts are possible due to drought conditions that may occur at late in the growing season. Poor seed/ pod/ fruit settings Low crop yields Low quality produce Increased susceptibility to pests All these impacts that may arise due to the water stress during a drought condition will ultimately result in reduced crop yields in terms of both quantity and quality with subsequent reduction in farm income.
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2. Land degradation Land degradation is a process of decay in the land’s physical and biological resources, which continues until it reduces the land’s advantages for human use and environmental sustainability. Under drought conditions which usually associate with high temperature regime speeds up the decaying of organic matter in soil with subsequent destruction of soil structure, This will lead to reduction of land’s productivity due to enhanced soil erosion and poor physical, chemical and biological properties of the soil.
In areas where the ground water is inherently saline, high evaporation rates during drought conditions bring dissolved salts of ground water to the soil surface with the capillary rise at lower positions of the catenal sequence of land. Water will immediately evaporates in to the atmosphere under high evaporative demand of the atmosphere leaving salts on surface layer of soil. If the subsequent rains after the drought are not sufficient to wash away these salts, the process will continue until the land becomes completely unproductive due to salinization. Salinity affected paddy field
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3. Impact of droughts on soil microbial activity and fertility in the soil The health of the soil is dependent upon many factors including fertility, pH and adequate moisture to support microorganisms, mainly bacteria, fungi and actinomycetes. Vigorous microbial activity is the strongest indication that any given soil will support a thriving plant community. It is a well known fact that drought or soil moisture stress will negatively affect the soil micro-organisms. Soil microorganisms number is nearly a trillion in each pound of root-zone soil. Over 98% of them are labeled â&#x20AC;&#x153;the decomposers.â&#x20AC;? Their functions include formation of soil aggregates to improve air and water movement; decomposition of organic matter including thatch to humus and solubilizing insoluble mineral nutrients such as phosphates, sulfates and potassium, calcium and magnesium oxides to plant available forms. Hence, reduction in microbial activities due to drought may hinder all those processes with subsequent reduction of overall soil fertility.
4. Increased threat of invasive species and loss of Bio-diversity Invasive species are non-indigenous species, plants or animals that adversely affect the habitats they invade economically, environmentally or ecologically. Under drought conditions where water stress and high ambient temperature is a common feature, any plant or animal species that can outcompete with available resources will survive and reproduce fast. It is also believed that many highly adaptable invasive plants and animals will out-compete less adaptable native species in the stressful conditions of a drought. Generally, endemic species have several natural enemies and hence, they are unable to outcompete non-indigenous species under stress environment of a drought resulting propagation of non-indigenous invasive species at an un-controllable rate.
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Invasive plant spp (Mimosa pigra)
Droughts that kill native plants can leave gaps in vegetation that may be quickly occupied by invasive species. Therefore, threat of invasive species will be inevitable in a drought prone area of a country and it will remain true for Sri Lanka as well. A variety of factors put stress on the diverse life forms that are important for agricultural activities including crop wild relatives. Perhaps the greatest threats to our natural heritage, the highest biodiversity in the region could be the frequent droughts during recent times that emerged as a result of climate change. Examples of Crop wild relatives that are threatened by drought Wild bitter gourd (Mormodica dioica)
Kowakka (Coccinia grandis)
While frequent drought conditions will benefit certain plants and animals that are invasive, many native species which are important for agriculture including crop wild relatives will be affected by drought conditions. Environmental changes that are occurring along with droughts are far more rapid than plants and animalsâ&#x20AC;&#x2122; ability to adopt to the changing situation.
5. Impacts on the livelihood Farmers are not the only ones who suffer from droughts. Retailers who provide goods and services to farmers must deal with reduced business. This later leads to unemployment and loss of tax revenue for the government. The recreational and tourism industries are seriously affected because tourists do not want to travel to a country that is suffering from a severe water shortage. Shortages of certain goods results in the costly importation of necessary goods from outside the affected area. All these things will affect the livelihood of the people in the country especially in the peasant sector. - 14 -
Floods in Sri Lanka Flood refers to a body of water covering an area which is normally a dry land. Floods may occur along the river banks, lakes and sea coast. However, river floods are most common. River floods and lake floods occur because of too much water flowing into them that overflows its banks, or sometimes even breaks the banks. The excess water is the result of excessive rains in the catchment area. Sea floods are caused by unusually strong sea waves hitting the coast. This may happen at the time of cyclonic storms or by tsunami waves. Almost every year some parts of Sri Lanka is affected by floods. In identifying vulnerable areas for floods, in addition to rainfall, physiographic profile of the land need to be considered. There are three distinct physiographic regions in Sri Lanka (Map 2). The lower peneplain includes the coastal plain and the highland up to an elevation of 300m above MSL which is commonly known as the Low Country (LC). The land surface between 300m and 900m is the middle peneplain and it is referred as the Mid Country (MC). All land surfaces above 900m MSL is the upper peneplain and it is referred as the Up Country (UC). Sri Lanka has 103 river basins most of which originate in the Central Highlands and flow in a radial pattern to the Indian ocean. Most of these rivers are small in width and short in length. There are 16 principal rivers longer than 100 kilometers in length, with 12 of them carrying about 75 percent of the mean river discharge of the entire country. The longest rivers are the Mahaweli Ganga (335 kilometers) and the Aruvi Aru (170 kilometers). In the highlands, river courses are frequently broken by discontinuities in the terrain, and where they encounter escarpments, numerous waterfalls and rapid down-flows have eroded the passage. Once they reach the plain, the rivers slow down and the waters meander across flood plains and deltas. The upper reaches of the rivers are wild and usually not navigable, and the lower reaches are prone to seasonal flooding.
Water falls and rapid down falls in highland
Flood plane towards the sea
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Map 2: Three distinct physiographic regions â&#x20AC;&#x201C; Up Country, Mid Country and Low Country.
Flood Areas of Sri Lanka While major rivers such as Kalu, Kelani, Nilwala and Mahaweli are vulnerable to frequent floods during high rainfall events, flood hazards are a common feature mainly in the Wet zone of Sri Lanka. Table 1 shows the hydrological characteristics of main river basins located in the Wet zone. Out of six major river basins in the Wet zone, Kelani Ganga and Kalu Ganga record the highest flood frequencies and the accompanied flood damages. Table 1: Hydrological characteristics of major river basins in the wet zone. Name Kalu ganga Kelani ganga Ging ganga Deduru oya Ma oya Nilwala ganga
Catchment Length - km area km2 2,720 2,292 932 2,647 1,528 971
132 147 111 140 132 101
Annual rainfall - mm
Mean annual discharge - mm3
3,500 3,600 3,500 1,750 2,500 2,500
7,862 5,474 1,903 1,608 1,608 1,104
Source: Ministry of Environment Publication, 2000.
Maximum flood peaks of Sri Lanka also have been reported in these rivers. Kalu Ganga is the third longest river of Sri Lanka meandering through Ratnapura with highest amount of discharge to the sea. Ratnapura city area subjects to floods when Kalu Ganga rises to 66.5ft MSL and during the worst floods which occurred in 1913, 1940, 1941, 1989 and 2003, the river reached slightly above 80ft MSL (Source: Irrigation Department). - 16 -
Floodplains of the river Kelani Ganga also are subjected to frequent floods during intense rainy weather. Being located in this floodplain, some parts of the capital, Colombo (1-6m MSL) have also become highly vulnerable to floods. There had been major floods in Colombo area during October 1913, May 1927, May 1939, May 1940, August 1947, October 1966, October 1967, July 1989. Many parts of the capital city went under water on June 05, 1992 when 494mm of rain fell in 24 hours. In recent times, flash floods have become more common in the capital city attributed to the combination of extreme rainfall events and a variety of human influences especially, the filling of wetlands. Apart from these, floods do occur in the Dry and Intermediate zones of Sri Lanka with an additional risk of possible sudden breaching of silted-up tanks and reservoirs. These two climatic zones consist of large number of earth-filled dams built during the ancient times.
Kanthale dam damaged on 20th April 1986 (Irrigation Engineer R.C. Jayasingha, Kanthale. Date: 20.04.2006)
The most recent catastrophic floods were in June 1989 when Kalu Ganga, Kelani Ganga, Gin Ganga over topped their banks due to heavy southwest monsoon rains. It has been reported that 300 people died and 15,000 houses were damaged from this devastating flood occurred mainly in the Wet zone of Sri Lanka. The other was in May 17, 2003 with 350mm of rainfall received overnight in and around Ratnapura Kalutara, Galle and Matara districts. This flood caused severe damages to human lives and infrastructure accounting 235 deaths and 17 missing persons. The main causes for the frequent occurrence of floods in Sri Lanka are heavy seasonal rainfall, illegal deforestation, lack of flood protection schemes, unplanned development activities including filling of wetlands. The flood could occur in the flood plain of the Mahaweli Ganga, especially at its lower reaches in the eastern province with significant damages to large scale paddy tracts in the area. This could happen during October to December period due formation of weather systems in the Bay of Bengal and highly active north east monsoon rains.
Floods in Ampara
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Impacts of floods on agriculture and livelihood
1. Crops and cropping systems vulnerable for flood hazard As the flood water is moving away from sloping terrain, it will remain in flood plains for a few days depending on how flat the terrain and state of its associated drainage network. Hence, crops that are grown in the flood plains can be severely affected depending on the number of days that they are submerged and rate at which flood water moves away from the area. These crops are mainly, paddy, vegetables grown on paddy lands and occasionally some homegardens trees and crops. Tree crops such as coconut palms and fruit trees will have hardly any impact by flood unless fast moving flood water would up-root them. Damage to the annual crops will have greater variability from recoverable damages to complete crop devastation depending on the type of crops and the age at which submergence occurred. If it is a complete washing away of crops, farmers are compelled to find seed materials for the next attempt. Even though there is a slim chance to find required seed materials from the area itself, the most probable outcome would be unavailability of preferred variety or age class that farmers look for. Ultimately, all these will lead to high cost of cultivation, reduce crop production and loss of anticipated farm income with subsequent negetive impacts on the livelihood.
2. Sand filling After the flood water is drained off naturally, it is a common picture in the paddy tracts in the flood plains of Sri Lanka to observe piled up sand and silts along with large quantity of debris. Before the re-start of the cultivation, these materials have to be removed with a high cost of labour.
3. Damages to infrastructure Apart from damages to community infrastructure such as bridges, buildings and roads, there is a strong threat to agricultural infrastructures being damaged under flood situations. This may range from washing away of dikes in paddy tracts and damage to canals in irrigation systems, anicuts in diversion schemes to breaching of earth filled dams of both minor and major tank categories. This will be an additional burden for farmers and the government as a whole. This could results some lands to leave behind from agriculture for several seasons until the rehabilitation works are completed.
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4. Loss of added fertilizer Irrespective of the magnitude of the flood, any added fertilizers will wash away from the agricultural fields with moving flood water, especially from paddy tracts. This will lead to increase the cost of cultivation of the crop as farmer has to re-apply it. Meanwhile, some paddy tracts are to be benefited from minor scale floods as they will deposit very fertile silts in these paddy tracts.
5. Reduced seed paddy production One of the most significant impacts of floods in rice growing areas is the reduction of seed paddy production for the following season. If the harvesting time of the crop coincides with unusual rain spells, seed paddy production can not be done. It will not only affect the farmersâ&#x20AC;&#x2122; current income but also leads into severe shortage of seed material for the next season too with a subsequent web of negative impacts. What ever discussed in above sections will ultimately lead to the high cost of cultivation, reduced production both in terms of quantity and quality with subsequent loss of farm income affecting the livelihood of the farming community. It will also affect other service providers of the area who supply necessary input for cultivation and other day to day needs such as groceries, transport etc.
Impacts of floods on environment 1. Soil erosion and siltation
During a flood, rivers will carry large masses of soil and plant debris and deposit them downstream. These deposits reduce the flowing capacity of the river resulting in overflows and meandering of the river, and erosion of the riverbank with subsequent siltation of the downstream.
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2. Pollution of surface water bodies Soils generally contain human waste, fertilizers, pesticides, and improperly disposed industrial waste. These contaminants will mix up with surface water bodies with the retreating flood water and runoff water from adjoining highlands.
3. Increase threat of invasive species and biodiversity Occurrence of floods enables invasive species to escape from local and constrained environments to more fertile agricultural lands in the downstream. They will proliferate at an uncontrollable rate and compete with agricultural crops for available resources such as water and nutrients resulting in reduced yields in terms of both quantity and quality. The best example is â&#x20AC;&#x153;Yoda Nidikumbaâ&#x20AC;? (Mimosa pigra). Long lasting submergence under flooding is likely to destroy some plants which are not adapted to such conditions and hence, some species may reach near extinction or extinction. Nevertheless, eco-systems in flood plains like Villu are well adapted to flooding, and therefore, significant impact on biodiversity may not occur in such environments.
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CHAPTER - 2
CLIMATE AND SOILS OF DIVISIONAL SECRETARIAT AREAS - 22 -
Agro ecological zones
ntire agro ecology of Sri Lanka has been traditionally generalized in to three climatic zones as “Wet Zone” in the southwestern region including central hill country, “Dry Zone” covering predominantly, northern and eastern part of the country and “Intermediate zone”, which seperates the dry and wet zones skirting the central hills except in the south and the west (Map 3). In differentiating aforesaid three climatic zones, rainfall, contribution of southwest monsoon rains, soils, land use and vegetation have been widely considered. The Wet zone receives relatively a high mean annual rainfall over 2,500mm without pronounced dry periods. The Dry zone receives a mean annual rainfall of less than 1,750mm with a distinct dry season from May to September. The Intermediate zone receives a mean annual rainfall ranged from 1,750 to 2,500mm with a short and less prominent dry season. Taking elevation in to account as a proxy for ambient temperature, these three climatic zones have been delineated in to seven agro-climatic zones under three elevation classes, namely, Up country (> 900m), Mid country (300 – 900m) and Low country (< 300m). In this classification, both Wet and Intermediate zones spread across all three elevation classes while the Dry zone is confined only to the Low country. Finally, these seven agro-climatic zones have been further delineated in to 46 agro-ecological regions based on the amount and distribution of monthly rainfall and contribution from aforesaid four rainfall seasons to the annual rainfall. Resulting map identifies 11 agro-ecological regions in the Dry zone while 15 and 20 regions in the Wet and Intermediate zones respectively.
Vulnerability to drought and floods in agro ecological zones Table 2: Vulnerability to drought or flood in major Agro ecological regions. Agro ecological region Vulnerability to drought/flood Wet zone Slim chance of occurring drought during yala Up, Mid and Low countries Low country WL2b and WL3 regions are vulnerable to drought during maha Flood condition occurs during maha where rice is grown Intermediate zone The drought proneness is relatively higher compared to the Up, Mid and Low wetter part of the country countries Mid country Some parts are subjected to drought during yala Low country Vulnerable to drought during the yala except the IL1a region Vulnerable to drought during maha except IL2 and IL1c regions Dry zone Highly vulnerable to drought during yala Low country Less susceptible to drought during maha compared to yala
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Mitigation actions may vary across a series of factors such as period of cultivation calendar, geographical location, agro-ecological zone and water source for irrigation. Therefore it is important to identify climatic and soil condition of various divisional secretarial areas for mitigation actions for drought and floods. Following pages depict the land terrain of the agro ecological zones, rainfall patterns and soil series. Please refer annex to study vulnerability to drought or flood of each agro ecological region.
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Map 3: Agro-ecological regions of Sri Lanka.
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Agro-ecological region Low Country Dry Zone - 1a (DL1a)
Low Country Dry Zone - 1b (DL1b)
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Vulnerability to drought/ flood
Hambagamuwa-Ketegal Ara Association, HambagamuwaKetegal Ara-Sevenagala Association, MahawalatennaHunnasgiriya-Weligepola Complex, SiyambalanduwaMuthukandiya Association with bed rock exposures, Timbolketiya-Pallagama Association, Walawe-Ketegal Ara Association, Walawe-Mahagal Ara-Ketegal Ara-Sevenagala Association, Weligepola, Muthukandia, not susceptible to drought
Hunnasgiriya, highly susceptible to drought Walawe, Hunnasgiriya, Muthukandiya, susceptible to drought Mahawalatenna, Siyambalanduwa, Weligepola, not susceptible to drought Ketagal Ara, Pallegama, Mahagal Ara, flood prone
Divisional secretarial areas - DL1a Balangoda, Buththala, Ambilipitiya, Haldummulla, Monaragala, Sewanagala, Siyabalanduwa, Thanamalvila, Weligepola, Wallawaya
Vulnerability to drought/ flood
Aluthwewa-Hurathgama Association, Aruvi Series associated with undifferentiated soils of alluvial origin with variable texture and drainage, Hambagamuwa-Ketegal Ara Association, Hambagamuwa-Ketegal Ara-Sevenagala Association, MahoWariyapola-Balalla Association with bed roc, MedawachchiyaAluthwewa-Divulwewa-Hurathgama-Nawagattegama Association, Medawachchiya-Aluthwewa-Kahatagasdegeliya Association with Lithosols derived from quartzite, Medawachchiya-Ranorawa-Elayapattuwa-HurathgamaNawagattegama Association, Medawachchiya-TadaratuCheddikulam-Hurathgama-Nawagattegama Association, Negombo-Gambura-Siyambala-Puttulam Association, Nonagama-Ranna-Ketegal Ara-Sevenagala Complex, RannaKetagal Ara Association, Ranna-Ketegal Ara-Sevenagala Association, Siyambalanduwa-Muthukandiya Association with bed rock exposures, Siyambalanduwa-Bibele-Lithosols Complex with bed rock exposures, Siyambalanduwa-ArantalawaHingurana-Damana Complex, Siyambalanduwa-Mutukandiya Association
Medawachchiya, Maho,Nonagama, Arantalawa, Hingurana, highly susceptible to drought Aluthwewa, Wariyapola, Tadarathu, Diwulwewa, Ranorawa, Ranna, Kahatagasdigiliya, Elayapattuwa, Cheddikulam, Siyabalanduwa, susceptible to drought Hurathgama, Aruvi, Negambo, Gambura, Puttalam, Sevanagala, Muthukandiya, Siyambala, Damana, not susceptible to drought Ketagal Ara, flood prone Nawagattegama salinity prone
Divisional secretarial areas - DL1b Ahatuwawa, Ambilipitiya, Ambalanthota, Ambanpola, Anamaduwa, Angunakolapalassa, Arachchikattuwa, Buththala, Dambulla, galenbindunuwawa, Galewela, Galgamuwa, Galnawa, Giribawa, Hambanthota, Hingurakgoda, Ipalogama, Kahatagasdigiliya, Karuwalagaswewa, Katharagama, Kabithigollawa, Kakirawa, Kotawehera, Lahugala, Lunugamvehera, Mahakumbukkadawala, Mahawa, Mahawilachchiya, Madawachchiya, Mihinthale, Monaragala, Nachchaduwa, Nawagaththegama, Nikawaratiya, Nochchiyagama, Nuwaragampalatha/ C, Nuwaragampalatha/ E, Palagala, Pallama, Palugaswewa, Polpithigama, Pothuvil, Puttalam, Rajanganaya, Rambawa, Rasnayakapura, Sewanagala, Siyabalanduwa, Sooriyawewa, Thalawa, Thangalla, Thabuththegama, Thanamalvila, Thirappane, Vauniya, Vauniya/ North, Vauniya/ South, Wengala cheddikulam, Weerakatiya, Wallawaya
- 27 -
Agro-ecological region Low Country Dry Zone - 1c (DL1c)
Low Country Dry Zone - 1d (DL1d)
- 28 -
Vulnerability to drought/ flood
Aluthwewa-Manampitiya Association with undifferentiated soils of alluvial origin, Aluthwewa-Hurathgama Association, Kaduruwela-Mutugala-Ulhitiya-Kuda Oya-Complex, Medawachchiya-Aluthwewa-Kahatagasdegeliya Association, Siyambala-Puttulam Association, Ukuwela-Hunugala Matale Association, Ulhitiya-Kuda Oya Association with bed rock exposures, Ulhitiya-Kuda Oya Association, Ulhitiya-WelikandaMutugala-Galwewa-Alawakumbura Complex with rock knob plains, Welikanda-Galwewa-Alawakumbura-Omadiyamadu Association
Medawachchiya, highly susceptible to drought Aluthwewa, Mutugala, Ulhitiya, Kuda Oya, Kaduruwela, Kahatagasdigiliya, Aluthwewa, Galwewa, Alawakumbura, Welikanda, susceptible to drought Hurathgama, Puttalam, Siyambala, Ukuwela, Matale, not susceptible to drought Manampitiya, susceptible to flood
Divisional secretarial areas - DL1c Alahara, Dambulla, Dehiaththakandiya, Dimbulagala, Hingurakgoda, Horowpathana, Kanthale, Kinniya, Lankapura, Mahaoya, Mahiyanganaya, Madirigiriya, Padiyathalawa, Seruvila, Thamankaduwa, Thampalagamuwa, Wilgamuwa
Vulnerability to drought/ flood
Kaduruwela-Mutugala-Ulhitiya-Kuda Oya-Complex Medawachchiya-Aluthwewa-Divulwewa-HurathgamaNawagattegama Association, Medawachchiya-AluthwewaKahatagasdegeliya Association, Medawachchiya-TadaratuCheddikulam-Hurathgama-Nawagattegama Association, Mullaittivu-Tanniyuttu-Vattappalai Association, NegomboNillaweli-Valaichchenai-Illuppaiyadichche Complex, SiyambalaPuttulam Association
Medawachchiya, highly susceptible to drought Mutugala, Ulhitiya, Kuda Oya, Kaduruwela, Divulwewa, Aluthwewa, Kahatagadigiliya, Tadaratu, Cheddikulam, susceptible to drought Hurathgama, Negambo, Siyambala, Puttalam, Illupatyadichenai, not susceptible to drought Nawagattegama salinity prone
Divisional secretarial areas - DL1d Gomarankadawala, Horowpathna, Kabithigollawa, Kuchchaweli, Maritime paththu, Morawewa, Padavi Siripura, Padaviya, Thambalagamuwa, Trincomalee
- 29 -
Agro-ecological region Low Country Dry Zone - 1e (DL1e)
Low Country Dry Zone - 1f (DL1f)
- 30 -
Vulnerability to drought/ flood
Gambura-Borupana-Mawillu Association, Kaduruwela-MutugalaUlhitiya-Kuda Oya-Complex, Medawachchiya-AluthwewaDivulwewa-Hurathgama-Nawagattegama Association, Medawachchiya-Aluthwewa-Kahatagasdegeliya Association, Medawachchiya-Tadaratu-Cheddikulam-HurathgamaNawagattegama Association, Mullaittivu-Tanniyuttu-Vattappalai Association, Siyambala-Puttulam Association
Medawachchiya, highly susceptible to drought Divulwewa, Aluthwewa, Kuda Oya, Ulhitiya, Kahatagasdigiliya, Tadaratu, Cheddikulam, Puttalam, susceptible to drought Gambura, Borupana, Hurathgama, Siyabmala, not susceptible to drought Nawagattegama salinity prone
Divisional secretarial areas - DL1e Galenbidunuwewa, Gomarankadawala, Hingurakgoda, Horowpathana, Kahatagasdigiliya, Kanthale, Kabithigollawa, Maritime Paththu, Morawewa, Oddusudan, Padavi Siripura, Padaviya, Palugaswewa, Pandiyankulama, Puthukkudierippu, Thambalagamuwa, Thunukkai, Vauniya/ North, Vauniya/ South
Vulnerability to drought/ flood
Akkarayan Kulam, Andigama-Willattawa-Gampaha Association, Aruvi Series associated with undifferentiated soils of alluvial origin with variable texture and drainage, GamburaBorupana-Mawillu Association, Medawachchiya-RanorawaElayapattuwa-Hurathgama-Nawagattegama Association, Tonigala-Anamaduwa-Nawagattegama Complex, WillpattuGambura-Borupana-Mawillu Association
Medawachchiya, Anamaduwa, highly susceptible to drought Ranorawa, Elayayapattuwa, Tonigala, susceptible to drought Gampaha, Andigama, Aruvi, Gambura, Borupana, Hurathgama, Mawillu, Wilpattu, Borupana, not susceptible to drought Nawagattegama salinity prone
Divisional secretarial areas - DL1f Karachchi, Karuwalagaswewa, Madu, Mahawilachchiya, Musali, Nochchiyagama, Oddusudan, Pandiyankulama, Puttalam, Rajanganaya, Thunukkai, Vauniya, Vauniya/ North, Wanathavilluwa, Wengalacheddikulam
- 31 -
Agro-ecological region Low Country Dry Zone - 2a (DL2a)
Low Country Dry Zone - 2b (DL2b)
- 32 -
Vulnerability to drought/ flood
Gal Oya Series associated with Undifferentiated Soils of alluvial origin, Negombo-Gambura-Siyambala-Puttulam Association, Siyambalanduwa - Muthukandiya Association with bed rock exposures, Siyambalanduwa -Bibele - Lithosols Complex with bed rock exposures, Siyambalanduwa-ArantalawaAkkaraipattuwa-Damana Complex with rock knob plains, Siyambalanduwa-Arantalawa-Damana Complex, Siyambalanduwa-Arantalawa-Hingurana-Damana Complex, Siyambalanduwa-Bibile-Lithosols Complex with bed rock exposures, Siyambalanduwa-Mutukandiya Association, Timbolketiya-Pallagama Association, Ulhitiya-Kuda Oya Association
Arrantalawa, Hingurana, highly susceptible to drought Siyambalanduwa, Bibile, Kuda Oya, Ulhitiya, susceptible to drought Gal Oya, Gambura, Negambo, Siyambala, Puttalam, Muthukandiya, Arantalawa, Akkaraipattuwa, Damana, Timbolketiya, not susceptible to drought Pallegama, susceptible to flood
Divisional secretarial areas - DL2a Ampara, Bibila, Damana, Eraurpaththu, Lahugala, Madulla, Mahaoya, Manmune west,Pothuwil, Siyabalanduwa, Thirukkovil, Uhana
Vulnerability to drought/ flood
Aluthwewa-Manampitiya Association with undifferentiated soils of alluvial origin, Gal Oya Series associated with Undifferentiated Soils of alluvial origin, Kaduruwela-MutugalaUlhitiya-Kuda Oya-Complex, Kaduruwela-Seruwila-Siyambala Association, Kaduruwela-Seruwila-Siyambala Association, Medawachchiya-Aluthwewa-Kahatagasdegeliya Association, Negombo-Gambura-Siyambala-Puttulam Association, Negombo-Nillaweli-Valaichchenai-Illuppaiyadichche Complex, Siyambalanduwa-Arantalawa-Akkaraipattuwa-Damana Complex with rock knob plains, Siyambalanduwa-Arantalawa-Damana Complex, Siyambalanduwa-Arantalawa-Hingurana-Damana Complex, Siyambala-Puttulam Association, Ulhitiya-Kuda Oya Association, Ulhitiya-Welikanda-Mutugala-GalwewaAlawakumbura Complex with rock knob plains, WelikandaGalwewa-Alawakumbura-Omadiyamadu Association
Medawachchiya, Arantalawa, Hingurana, Welikanda, highly susceptible to drought Aluthwewa, Kaduruwela, Mutugala, Kuda Oya, Aluthwewa, Kahatagasdigiliya, Siyambalanduwa, Ulhitiya, Galwewa, Alawakumbura, Puttalam, susceptible to drought Gal Oya, Siyambala, Negambo, Gambura, Illayapadichenai, Valaicchenai, Akkaraipattuwa, Damana, not susceptible to drought Manampitiya susceptible to flood
Divisional secretarial areas - DL2b Akkareipaththuwa, Alayediwembu, Ampara, Addalachchena, Damana, Dimbulagala, Eachchalampaththu, Eraurpaththu village, Kalmune, Kanthale, Karathiw, Kaththankudi, Kinniya, Koraleipaththu, Koraleipaththu/ N, Koraleipaththu/ W, Lankapura, Mahaoya, Manmunai/ N, Manmunai Paththu, Manmunai/ S, Manmunai/ SW, Manmunai/ W, Madirigiriya, Morawewa, Muthur, Ninathiw, Porathiw Paththu, Pothuwil, Samanthure, Seruwila, Thamnkaduwa, Thambalagamuwa, Thurukkovil, Trincomalle, Uhana, Werugal, Walikanda
- 33 -
Agro-ecological region Low Country Dry Zone - 3 (DL3)
Low Country Dry Zone - 4 (DL4)
- 34 -
Vulnerability to drought/ flood
Andigama-Willattawa-Gampaha Association, Aruvi Series associated with undifferentiated soils of alluvial origin with variable texture and drainage, Gambura-Borupana-Mawillu Association, Mampuri-Siyambala-Puttulam Association, Medawachchiya-Ranorawa-Elayapattuwa-HurathgamaNawagattegama Association, Mullaittivu-Tanniyuttu-Vattappalai Association, Negombo-Nillaweli-Valaichchenai-Illuppaiyadichche Complex, Negombo-Puttulam Association, Siyambala-Puttulam Association, Tonigala-Anamaduwa-Nawagattegama Complex, Welipelessa Series, Willpattu-Gambura-Borupana-Mawillu Association, Calcic Red Yellow Latosols, Regosols, Soils on Recent Beach and Dune Sands, Solodized Solonetz and Solonchacks
Madawachchiya, Anamaduwa, highly susceptible to drought Ranorawa, Elayayapattuwa, Nilaweli, Puttalam, susceptible to drought Willattawa, Gamapaha, Andigama, Aruvi, Gambura, Borupana, Mawillu, Mampuri, Siyambala, Hurathgama, Nawagattegama, Negambo, Valachchenei, Illupayadichenai, Tonigala, not susceptible to drought
Divisional secretarial areas - DL3 Arachchikattuwa, Chankane, Chawakachcheri, Kalpitiya, Kandawali, Karachchi, Karaweddi, Karuwalagaswewa, Koopai, Madu, Mahakumbukkadawala, Mahawilachchiya, Manna, Manthai/ W, Maritime Paththu, Maruthankerni, Moondalama, Moosari, Nallur, Nanattan, Nochchiyagama, Oddusudan, Pachchilaipellai, Pandiyankulama, Point Paduru, Punarin, Puthukudiirippu, Puththlam, Sandilipai, Thelippale, Thunukkai, Uduwil (Chunnakam), Wanathawillauwa, Wengala Weddikulam
Vulnerability to drought/ flood
Gambura-Borupana-Mawillu Association, Mullaittivu-TanniyuttuVattappalai Association, Negombo-Puttulam Association, Regosols, Siyambala-Puttulam Association, Soils on Recent Beach and Dune Sands, Solodized Solonetz and Solonchacks
Regosols, highly susceptible to drought Gambura, Borupana, Mawillu, Mullaittivu, Vattappalai, Negambo, Puttalam, Siyambala, not susceptible to drought
Divisional secretarial areas - DL4 Delft, Kandawali, Karachchi, Kites, Madu, Manna, Mannai/ W, Maritime Paththu, Maruthankerni, Musali, Nanattan, Pachchalaipallai, Punarin, Welane
- 35 -
Low Country Dry Zone - 5 (DL5)
Up Country Intermediate Zone - 1 (IU1)
- 36 -
Vulnerability to drought/ flood
Negombo-Gambura-Siyambala-Puttulam Association, Nonagama-Ranna-Ketegal Ara-Sevenagala Complex, RannaKetegal Ara-Sevenagala Association, SiyambalanduwaMuthukandiya Association with bed rock exposures, Siyambalanduwa-Mutukandiya Association, TimbolketiyaPallagama Association
Nonagama, highly susceptible to drought Ranna, Katagal Ara, Siyabalanduwa, Puttalam, susceptible to drought Negambo, Gambura, Siyambala, Sevenagala, Muthukandiya, not susceptible to drought Pallegama,susceptible to flood
Divisional secretarial areas - DL5 Ambalanthota, Hambanthota, Katharagama, Lahugala, Lunugamwehera, Siyabalanduwa, Sooriyawewa, Thanamalwila, Thissamaharama
Vulnerability to drought/ flood
Hunnasgiriya Lithosols Complex with bed rock exposures, Wegala-Hunugala-Kundasale Mahaberiyatenna Complex
Hunnsagiriya, highly susceptible to drought Wegala, Hunugala, Kundasale, Mahaberiyatenna, not susceptible to drought
Divisional secretarial areas - IU1 Ambanganga Korale, Laggala-Pallegama, Madadumbara, Minipe, Naula, Panwila, Pathadumbara, Raththota, Udadumbara, Ukuwela
- 37 -
Up Country Intermediate Zone - 2 (IU2)
Up Country Intermediate Zone - 3a (IU3a)
- 38 -
Vulnerability to drought/ flood
Badulla-Lithosols Complex, Badulla-Mahawaletenna Complex, Kandy-Galigamuwa-Lithosols Complex, Nuwara Eliya-HortanLithosols Complex, Ragala Series, Rahugala-MahawalatennaBadulla-Lithosols Complex, Rikillagaskada Series, Ulhitiya (rolling)-Lithosols Complex with bed rock exposures
Ulhitiya, susceptible to drought Badulla, Mahawalatenna, Kandy, Nuwara Eliya, Hortan, Ragala, Galigamuwa, Rikillagaskada, not susceptible to drought
Divisional secretarial areas - IU2 Bibila, Delthota, Doluwa, Hanguranketha, Kadawathsathara korale, Meegahakiula, Nuwara Eliya, Passara, Pathahewahata, Ridimaliyadda, Walapane
Vulnerability to drought/ flood
Badulla, Mahawalatenna, Galigamuwa, not susceptible to drought
Divisional secretarial areas - IU3a Bandarawela, Haldummulla, Haputhale, Wallawaya
- 39 -
Up Country Intermediate Zone - 3b (IU3b)
Up Country Intermediate Zone - 3c (IU3c)
- 40 - 40 -
Vulnerability to drought/ flood
Badulla-Mahawaletenna Complex, Bandarawela Series, Horton-Lithosol Complex, Mahawalatenna-HunnasgiriyaWeligepola Complex, Malaboda-Lithosols Complex, MalabodaPallegoda-Dodangoda-Homagama Complex, NuwaraeliyaHortan-Lithosols Complex
Malabola, Homagama, Dodangoda, Hunnasgiriya, susceptible to drought
Badulla, Mahawalatenna, Bandarawela, Hortan, Nuwara Eliya, not susceptible to drought
Divisional secretarial areas - IU3b Haldummulla, Haputhale, Imbulpe, Nuwara Eliya, Walimada
Vulnerability to drought/ flood
Badulla-Mahawaletenna Complex, Bandarawela Series, Rahugala-Mahawalatenna-Badulla-Lithosols Complex, Welimada Lithosols Complex
Badulla, Mahawalatenna, Bandarawela, Welimada, Rahugala, not susceptible to drought
Divisional secretarial areas - IU3c Badalkumbura, Badulla, Bandarawela, Ella, Haldummulla, Haliela, Haputhale, Kandakatiya, Passara, Soranathota, Uwa Paranagama, Walimada, Wallawaya
- 41 -
Up Country Intermediate Zone - 3d (IU3d)
Up Country Intermediate Zone - 3e (IU3e)
- 42 -
Vulnerability to drought/ flood
Bandarawela Series, Nuwara Eliya-Hortan-Lithosols Complex
Bandarawela, Nuwara Eliya, Horton, not susceptible to drought
Divisional secretarial areas - IU3d Nuwara Eliya, Uwa Paranagama, Walimada
Soils Badulla-Mahawaletenna Complex, Bandarawela Series, Nuwara Eliya-Hortan-Lithosols Complex, Ragala Series, Welimada-Lithosols Complex
Vulnerability to drought/ flood Badulla, Mahawalatenna, Nuwara Eliya, Horton, Ragala, Welimada, not susceptible to drought
Divisional secretarial areas - IU3e Haliela, Haputhale, Nuwara Eliya, Uwa Paranagama, Walimada
- 43 -
Mid Country Intermediate Zone - 1a (IM1a)
Mid Country Intermediate Zone - 1b (IM1b)
- 44 -
Vulnerability to drought/ flood
Badulla-Lithosols Complex, Badulla-Mahawaletenna Complex, Bandarawela Series, Bibele-Dombagahawela Complex, Kandy-Galigamuwa-Lithosols Complex, Ragala Series, Rahugala-Mahawalatenna-Badulla-Lithosols Complex, Rikillagaskada Series, Ulhitiya-Kuda Oya Association with bed rock exposures, Ulhitiya (rolling)-Lithosols Complex with bed rock exposures, Welimada Lithosols Complex
Bibila, Dombagahawela, Galigamuwa, Hunnasgiriya, Ulhitiya, Kuda Oya, susceptible to drought Badulla, Mahawalatenna, Bandarawela, Kandy, Rikillagaskada, Welimada, not susceptible to drought
Divisional secretarial areas - IM1a Badulla, Bibila, Haliela, Hanguranketha, Kandakatiya, Meegahakiula, Passara, Rideemaliyadda, Soranathota, Uwa Paranagama, Walapane, Walimada
Vulnerability to drought/ flood
Aluthnuwara-Manampitiya Association with undifferentiated soils of alluvial origin, Aluthwewa-Hurathgama Association, Badulla-Mahawaletenna Complex, Hunnasgiriya Lithosols Complex with bed rock exposures, Medawachchiya-AluthwewaKahatagasdegeliya Association, Ukuwela-Hunugala-Matale Complex, Ukuwela-Hunugala Matale Association, Ulhitiya-Kuda Oya Association with bed rock exposures, Ulhitiya (rolling)Lithosols Complex with bed rock exposures, Ulhitiya-Kuda Oya Association
Medawachchiya, highly susceptible to drought Aluthwewa, Hunnasgiriya, Kahatagasdigiliya, Hunugala, Ulhitiya, Kuda Oya, susceptible to drought Badulla, Mahawalatenna, Ukuwela, Matale, not susceptible to drought Manampitiya, flood prone
Divisional secretarial areas - IM1b Alahara, Dambulla, Lakgala - Pallegama, Minipe, Naula, Udadumbara, Wilgamuwa
- 45 -
Mid Country Intermediate Zone - 1c (IM1c)
Mid Country Intermediate Zone - 2a (IM2a)
- 46 -
Vulnerability to drought/ flood
Badulla-Mahawaletenna Complex, Hunnasgiriya Lithosols Complex with bed rock exposures, Ragala Series, Rikillagaskada Series, Ulhitiya (rolling)-Lithosols Complex with bed rock exposures, Wegala-Hunugala-Kundasale Mahaberiyatenna Complex, Welimada Lithosols Complex
Hunnasgiriya, Ulhitiya, Hunugala, susceptible to drought Badulla, Mahawalatenna, Rikillagaskada, Mahaberiyatenna, Welimada, Ragala, Wegala, not susceptible to drought
Divisional secretarial areas - IM1c Hanguranketha, Kandakatiya, Madadumbara, Meegahakiula, Minipe, Soranathota, Udadumbara, Walapane
Vulnerability to drought/ flood
Badulla-Mahawaletenna Complex, Beliatta-Okewela Modarawana Complex, Dodangoda-Boralu Association, Mahawalatenna-Hunnasgiriya-Weligepola Complex, MalabodaLithosols Complex, Malaboda-Pallegoda-DodangodaHomagama Complex, Malaboda-Weddagala-Homagama Complex, Malaboda-Weddagala-Pallegoda Lithosols Complex, Walawe-Ketegal Ara Association
Hunnasgiriya, Boralu, Dodangoda, Malaboda, Homagama, Ketagal Ara, susceptible to drought Badulla, Mahawalatenna, Okawela, Beliatta, Pallegoda, Weddagala, not susceptible to drought
Divisional secretarial areas - IM2a Ambilipitiya, Balangoda, Godakawela, Haldummulla, Haputhale, Imbulpe, Katuwana, Kolonna korale, Opanayaka, Pasgoda, Waligepola
- 47 -
Mid Country Intermediate Zone - 2b (IM2b)
Mid Country Intermediate Zone - 3a (IM3a)
- 48 -
Vulnerability to drought/ flood
Badulla-Lithosols Complex, Badulla-Mahawaletenna Complex, Hambagamuwa-Ketegal Ara Association, HambagamuwaKetegal Ara Association, Hambagamuwa-Ketegal AraSevenagala Association, Mahawalatenna-HunnasgiriyaWeligepola Complex, Malaboda-Lithosols Complex, Malaboda-Pallegoda-Dodangoda-Homagama Complex, Rahugala-Mahawalatenna-Badulla-Lithosols Complex, Siyambalanduwa-Muthukandiya Association with bed rock exposures, Siyambalanduwa-Bibele-Lithosols Complex with bed rock exposures, Walawe-Ketegal Ara Association
Ketegal Ara, Hambagamuwa, Hunnasgiriya, Malaboda, Dodangoda, Homagama, Siyabalanduwa, Bibile, susceptible to drought Badulla, Pallegoda, Muthukandiya, Mahawalatenna, not susceptible to drought
Divisional secretarial areas - IM2b Badalbura, Balangoda, Bibila, Buththala, Ella, Haldummulla, Imbulpe, Madulla, Madagama, Monaragala, Passara, Siyabalanduwa, Thanamalvila, Waligepola, Wallawaya
Vulnerability to drought/ flood
Akurana-Kiribathkumbura Association, Kandy-GaligamuwaLithosols Complex, Ukuwela-Hunugala-Matale Complex, Ukuwela-Matale Association, Ulhitiya (rolling)-Lithosols Complex with bed rock exposures, Wegala-Hunugala-Kundasale Mahaberiyatenna Complex
Galigamuwa, Hunugala, Kundasale, Ulhitiya, susceptible to drought Kiribathkumbura, Akurana, Kandy, Ukuwela, Matale, Wagala, Galigamuwa, not susceptible to drought
Divisional secretarial areas - IM3a Ambanganga Korale, Kundasale, Kandy, Matale, Mada Dumbara, Panwila, Patha Dumbara, Pathahewahata, Raththota, Ukuwela
- 49 -
Mid Country Intermediate Zone - 3b (IM3b)
Mid Country Intermediate Zone - 3c (IM3c)
- 50 -
Vulnerability to drought/ flood
Aluthwewa-Manampitiya associated with undifferentiated soils of alluvial origin, Aluthwewa-Hurathgama Association, Hunnasgiriya Lithosols Complex with bed rock exposures, Kandy-Matale Association, Kiruwana-Melsiripura Association, Ukuwela-Hunugala-Matale Complex, Ukuwela-Hunugala Matale Association
Hunnasgiriya, Aluthwewa, Hunugala, Kiruwana, susceptible to drought Kandy, Hurathgama, Matale, Ukuwela not susceptible to drought Manampitiya, susceptible to flood
Divisional secretarial areas - IM3b Ambanganga Korale, Dambulla, Galewela, Ibbagamuwa, Matale, Naula, Pallepola, Polpithigama, Yatawaththa
Vulnerability to drought/ flood
Hunnasgiriya Lithosols Complex with bed rock exposures, Kandy-Galigamuwa-Lithosols Complex, Rikillagaskada Series, Ukuwela-Matale Association, Ulhitiya (rolling)-Lithosols Complex with bed rock exposures
Wegala-Hunugala-Kundasale Mahaberiyatenna Complex Hunnasgiriya, Galigamuwa, Hunugala, Ulhitiya, Kundasale, susceptible to drought Kandy, Rikillagaskada, Ukuwela, Wegala, Mahaberiyatenna, not susceptible to drought
Divisional secretarial areas - IM3c Delthota, Hanguranketha, Kundasale, Kadawathsathara Korale, Madadumbara, Pathahewahata, Udadumbara
- 51 -
Low Country Intermediate Zone - 1a (IL1a)
Low Country Intermediate Zone - 1b (IL1b)
- 52 -
Vulnerability to drought/ flood
Aluthwewa-Hurathgama Association, Andigama-WillattawaGampaha Association, Beliatta-Okewela-Modarawana Complex, Boralu-Madabokka Complex, Dodangoda-Boralu Association, Kandy-Matale Association, Kiruwana-Kurunegala-Batalagoda Association, Kiruwana-Melsiripura Association, Kuruwita-Kuliyapitiya-Kurunegala-Batalagoda-Assosiation, Maho-Wariyapola-Balalla Association with bed rock exposures Mampuri Series, Mawanella-Kandy-Kiribathkumbura Association, Minuwangoda-Gampaha Association, Negombo-Katunayake Association, Negombo-Puttulam Association, PalatuwaWagura-Madabokka Complex, Palatuwa-Wagura-Madabokka Complex; Pallegoda-Dodangoda-Homagama Complex, Ratupasa -Katunayake Association, Siyambala-Puttulam Association, Wagura-Palatuwa Complex, Welipelessa Series, WelipelessaPalugaswewa Association, Willpattu-Gambura-BorupanaMawillu Association
Aluthwewa, Boralu, Dodangoda, Kurunegala, Maho, Melsiripura, Wariyapola, Puttalam, Homagama, Dodandowa, Puttalam, Kiruwana, susceptible to drought Hurathgama, Modarawana, Okawela, Beliatta, Kandy, Matale, Batalagoda, Kuliyapitiya, Mawanella, Kiribathkumbura, Gampaha, Katunayake, Welipelessa, Palugaswewa, Wilpattu, Borupana, Mawillu, Gambura, Negambo, not susceptible to drought Palatuwa, Madabokka, Wagura, susceptible to flood
Divisional secretarial areas - IL1a Alawwa, Bingiriya, Chilaw, Dankotuwa, Devinuwara, Diulapitiya, Ganewaththa, Hakmana, Ibbagamuwa, Kamrupitiya, Katana, Katupotha, Kirinda-Puhulwella, Kuliyapitiya/ E, Kuliyapitiya/ W, Kurunagala, Madampe, Mahawewa, Malinbada, Mallawapitiya, Maspotha, Mathra, Mawathagama, Mulatiyana, Narammala, Naththandiya, Negambo, Okewela, Panduwasnuwara, Pannala, Polgahawela, Rambukkana, Rideegama, Thihagoda, Thumpane, Udubaddawa, Wariyapola,Weerambugedara, Waligama, Wennappuwa
Vulnerability to drought/ flood
Aluthwewa-Hurathgama Association, Beliatta-OkewelaModarawana Complex, Boralu-Madabokka Complex, Dodangoda-Boralu Association, Mahawalatenna-HunnasgiriyaWeligepola Complex, Malaboda-Weddagala-Pallegoda Lithosols Complex, Minuwangoda-Gampaha Association, Negombo-Katunayake Association, Negombo-GamburaSiyambala-Puttulam Association, Nonagama-Ranna-Ketegal Ara-Sevenagala Complex, Ranna-Ketagal Ara Association, Ranna-Ketegal Ara-Sevenagala Association, Ratupasa Katunayake Association, Wagura-Palatuwa Complex, Walawe-Ketegal Ara Association
Nonagama, highly succeptible to drought Aluthwewa, Boralu, Dodangoda, Hunnasgiriya, Puttalam, Malaboda, Ketagal Ara, Ranna, Sevenagala, Ratupasa, susceptible to drought Hurathgama, Modarawana, Okawela, Beliatta, Weligepola, Mahawalatenna, Weddagala, Pallegoda, Negambo, Katunayake, not susceptible to drought Madabokka, Wagura, Palatuwa, susceptible to flood
Divisional secretarial areas - IL1b Angunakolapalassa, Arachchikattuwa, Beliaththa, Bingiriya, Chilaw, Dewinuwara, Dikwella, Ambilipitiya, Ganewaththa, Hakmana, Katupotha, Katuwana, Kirinda puhulwella, Kobeigane, Kolonna korale, Madampe, Mahakumbukkadawala, Maspotha, Mathara, Mulatiyana, Mundalama, Okewela, Pallama, Panduwasnuwara, Rasnayakapura, Thangalla, Wariyapola, Weerakatiya
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Low Country Intermediate Zone - 1c (IL1c)
Low Country Intermediate Zone - 2 (IL2)
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Vulnerability to drought/ flood
Badulla-Lithosols Complex, Bibele-Dombagahawela Complex, Hambagamuwa-Ketegal Ara Association, MahawalatennaHunnasgiriya-Weligepola Complex, Malaboda-PallegodaDodangoda-Homagama Complex, Malaboda-WeddagalaHomagama Complex, Rahugala-Mahawalatenna-BadullaLithosols Complex, Siyambalanduwa-Muthukandiya Association with bed rock exposures, Siyambalanduwa-Bibile-Lithosols Complex with bed rock exposures, Walawe-Ketegal Ara Association, Walawe-Mahagal Ara-Ketegal Ara-Sevenagala Association
Bibile, Dombagahawela, Ketagal Ara, Hunnasgiriya, Homagama, Dodangoda, Malaboda, Siyabalanduwa, susceptible to drought Badulla, Weligepola, Weddagala, Mahawalatenna, Rahugala, Muthukandiya, not susceptible to drought
Divisional secretarial areas - IL1c Badalkumbura, Balangoda, Bibila, Buththala, Ambilipitiya, Godakawela, Madulla, Madagama, Monaragala, Siyabalanduwa, Waligepola, Wallawaya
Vulnerability to drought/ flood
Aluthnuwara-Manampitiya Association with undifferentiated soils of alluvial origin, Aluthwewa-Hurathgama Association, Badulla-Lithosols Complex, Badulla-Mahawaletenna Complex, Bibele-Dombagahawela Complex, Gal Oya Series associated with Undifferentiated Soils of alluvial origin, HunnasgiriyaLithosols Complex with erosional remnants, SiyambalanduwaMuthukandiya Association with bed rock exposures, Siyambalanduwa-Bibile-Lithosols Complex with bed rock exposures, Siyambalanduwa-Arantalawa-Damana Complex, Siyambalanduwa-Bibile-Lithosols Complex with bed, Ulhitiya-Kuda Oya Association with bed rock exposures, Ulhitiya (rolling)-Lithosols Complex with bed rock exposures, Ulhitiya-Kuda Oya Association
Arantalawa, highly susceptible to drought Aluthwewa, Dombagahawela, Bibile, Hunnasgiriya, Siyabalanduwa, Ulhitiya, susceptible to drought Badulla, Hurathgama, Mahawalatenna, Muthukandiya, Gal Oya, Damana, Kuda Oya, not susceptible to drought Manampitiya, susceptible to flood
Divisional secretarial areas - IL2 Bibila, Alahara, Kandakatiya, Lakgala Pallegama, Madulla, Mahaoya, Mahiyangana, Madagama, Meegahakiula, Minipe, Monaragala, Naula, Padiyathalawa, Ridimaliyadda, Siyambalanduwa, Walapane, Wilgamuwa
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Low Country Intermediate Zone - 3 (IL3)
Up Country Wet Zone - 1 (WU1)
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Vulnerability to drought/ flood
Aluthwewa-Hurathgama Association, Andigama-WillattawaGampaha Association, Kiruwana-Kurunegala-Batalagoda Association, Kiruwana-Melsiripura Association, MahoWariyapola-Balalla Association with bed rock exposures, Medawachchiya-Aluthwewa-Divulwewa-HurathgamaNawagattegama Association, Ukuwela-Hunugala-Matale Complex, Ukuwela-Hunugala Matale Association, Welipelessa Series, Welipelessa-Palugaswewa Association
Madawachchiya, highly susceptible to drought Aluthwewa, Kurunegala, Melsiripura, Maho, Wariyapola, Balalla, Divulwewa, Kiruwana, susceptible to drought Hurathgama, Andigama, Gampaha, Willattawa, Batalagoda, Nawagattegama, Ukuwela, Palugaswewa, Welipelessa, not susceptible to drought
Divisional secretarial areas - IL3 Ambanpola, Arachchikattuwa, Bingiriya, Dambulla, Glewela, Ganewaththa, Ibbagamuwa, Kobeigane, Kotawehera, Mahakumbukkadawala, Mahawa, Maspotha, Naula, Nikawaratiya, Palagala, Pallama, Panduwasnuwara, Polpithigama, Rasnayakapura, Wariyapola
Vulnerability to drought/ flood
Aluthwewa-Hurathgama Association, Andigama-WillattawaGampaha Association, Kiruwana-Kurunegala-Batalagoda Association, Kiruwana-Melsiripura Association, MahoWariyapola-Balalla Association with bed rock exposures, Medawachchiya-Aluthwewa-Divulwewa-HurathgamaNawagattegama Association, Ukuwela-Hunugala - Matale Complex, Ukuwela-Hunugala Matale Association, Welipelessa Series, Welipelessa-Palugaswewa Association
Madawachchiya, highly susceptible to drought Aluthwewa, Kurunegala, Melsiripura, Maho, Wariyapola, Diwulwewa, Hunugala, Kiriwana, susceptible to drought Hurathgama, Gampaha, Andigama, Willathawa, Batalagoda, Balalla, Ukuwela, Welipelessa, Palugaswewa, not susceptible to drought
Divisional secretarial areas - WU1 Ambagamuwa Korale, Aranayaka, Balangoda, Bulathkohupitiya, Daraniyagala, Gangaihalakorale, Godakawela, Imbulpe, Kahawaththa, Kalawana, Kolonna Korale, Kotapola, Kothmale, Kuruwita, Niwithigala, Nuwara Eliya, Pasbage Korale, Rathnapura, Yatiyanthota
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Agro-ecological region Up Country Wet Zone - 2a (WU2a)
Up Country Wet Zone - 2b (WU2b)
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Vulnerability to drought/ flood
Horton-Lithosol Complex, Kandy-Galigamuwa-Lithosols Complex, Mattekele Series, Nuwaraeliya-Hortan-Lithosols Complex
Galigamuwa, susceptible to drought Hortan, Kandy, Mattekele, Nuwara Eliya, not susceptible to drought
Divisional secretarial areas - WU2a Ambagamuwa Korale, Doluwa, Hanguranketha, Nuwara Eliya
Vulnerability to drought/ flood
Horton-Lithosol Complex, Kandy-Galigamuwa-Lithosols Complex, Malaboda-Lithosols Complex, Maskeliya-MattekeleLithosols Complex, Mattekele Series, Nuwaraeliya-HortanLithosols Complex
Galigamuwa, Malaboda, Maskeliya, susceptible to drought Hortan, Kandy, Mattekele, Nuwara Eliya, not susceptible to drought
Divisional secretarial areas - WU2b Ambagamuwa Korale, Delthota, Doluwa, Hanguranketha, Imbulpe, Kothmale, Nuwara Eliya, Udapalatha
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Agro-ecological region Up Country Wet Zone - 3 (WU3)
Mid Country Wet Zone - 1a (WM1a)
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Vulnerability to drought/ flood
Badulla-Mahawaletenna Complex, Horton-Lithosol Complex, Kandy-Galigamuwa-Lithosols Complex, Nuwara Eliya-HortanLithosols Complex
Galigamuwa, susceptible to drought Badulla, Mahawalatenna, Hortan, Kandy, Nuwara Eliya, not susceptible to drought
Divisional secretarial areas - WU3 Ambagamuwa Korale, Haldummulla, Haguranketha, Imbulpe, Kothmale, Nuwara Eliya, Walimada
Vulnerability to drought/ flood
Galigamuwa-Homagama Complex, Kandy-GaligamuwaLithosols Complex, Malaboda-Lithosols Complex, Malaboda-Pallegoda-Dodangoda-Homagama Complex, Malaboda-Weddagala-Pallegoda Lithosols Complex, Maskeliya-Mattekele-Lithosols Complex, Mawanella-KandyKiribathkumbura Association, Pallegoda-Dodangoda-BoraluGampaha Association
Galigamuwa, Homagama, Dodangoda, Malaboda, Boralu, susceptible to drought Kandy, Pallegoda, Weddagala, Maskeliya, Mattekele, Mawanella, Kiribathkumbura, Gampaha, not susceptible to drought
Divisional secretarial areas - WM1a Agalawaththa, Ambagamuwa Korale, Aranayaka, Balangoda, Bulathkohupitiya, Dehiowita, Daraniyagala, Gangaihalakorale, Godakawela, Kalawana, Kagalle, Kolonnakorale, Kotapola, Kothmale, Kuruwita, Neluwa, Niwithigala, Opanayaka, Pasbagekorale, Pasgoda, Palmadulla, Pitabaddara, Rthnapura, Yatiyanthota
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Agro-ecological region Mid Country Wet Zone - 1b (WM1b)
Mid Country Wet Zone - 2a (WM2a)
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Vulnerability to drought/ flood
Dodangoda-Boralu Association, Malaboda-Lithosols Complex, Malaboda-Pallegoda-Dodangoda-Homagama Complex, Malaboda-Weddagala-Homagama Complex, MalabodaWeddagala-Pallegoda Lithosols Complex
Dodangoda, Boralu, Malaboda, Homagama, susceptible to drought Pallegoda, Weddagala, not susceptible to drought
Divisional secretarial areas - WM1b Agalawaththa, Ayagama, Balangoda, Elapatha, Godakawela, Imbulpe, Kahawaththa, Kalawana, Katuwana, Kolonnakorale, Mulatiyana, Niwithigala, Opanayaka, Pasgoda, Rathnapura
Vulnerability to drought/ flood
Gampola Series, Kandy-Galigamuwa-Lithosols Complex, Mawanella-Kandy-Kiribathkumbura Association
Galigamuwa, susceptible to drought Gampola, Kandy, Mawanella, Kiribathkumbura, not susceptible to drought
Divisional secretarial areas - WM2a Aranayaka, Delthota, Doluwa, Gangaihalakorale, Kothmale, Mawanella, Pasbagekorale, Udapalatha
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Agro-ecological region Mid Country Wet Zone - 2b (WM2b)
Mid Country Wet Zone - 3a (WM3a)
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Vulnerability to drought/ flood
Akurana-Kiribathkumbura Association Galigamuwa-Homagama Complex, Gampola Series, Kandy-Galigamuwa-Lithosols Complex, Kandy-Matale Association, Mawanella-Kandy-Kiribathkumbura Association
Galigamuwa, Homagama, susceptible to drought Akurana, Gampola, Kiribathkumbura, Matale, Mawanella, not susceptible to drought
Divisional secretarial areas - WM2b Aranayaka, Delthota, Doluwa, Gangaihalakorale, Harispaththuwa, Kagalle, Kandy, Mawanella, Thumpane, Udapalatha, Udunuwara, Yatinuwara
Vulnerability to drought/ flood
Akurana-Kiribathkumbura Association, Kandy-Matale Association, Kiruwana-Kurunegala-Batalagoda Association, Mawanella-Kandy-Kiribathkumbura Association, MinuwangodaGampaha Association
Kurunegala, Minuwangoda, Kiruwana, susceptible to drought Akurana, Kandy, Matale, Kiribathkumbura, Mawanella, Batalagoda, Gampaha, not susceptible to drought
Divisional secretarial areas - WM3a Aranayaka, Harispaththuwa, Mallawapitiya, Mawanella, Mawathagama, Pujapitiya, Rambukkana, Thumpane, Udunuwara, Yatinuwara
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Agro-ecological region Mid Country Wet Zone - 3b (WM3b)
Low Country Wet Zone - 1a (WL1a)
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Vulnerability to drought/ flood
Akurana-Kiribathkumbura Association, Hunnasgiriya-Lithosols Complex with erosional remnants, Kandy-Galigamuwa-Lithosols Complex, Kandy-Matale Association, Kiruwana-Melsiripura Association, Ukuwela-Hunugala-Matale Complex, UkuwelaMatale Association, Ulhitiya (rolling)-Lithosols Complex with bed rock exposures, Wegala-Hunugala-Kundasale Mahaberiyatenna Complex
Hunnasgiriya, Galigamuwa, Melsiripura, Hunugala, Ulhitiya, Kundasale, Kiruwana, susceptible to drought Akurana, Kandy, Matale, Kiribathkumbura, Mawanella, Batalagoda, Gampaha, Ukuwela, Wegala, Mahaberiyatenna, not susceptible to drought
Divisional secretarial areas - WM3b Akurana, Harispaththuwa, Ibbagamuwa, Kundasale, Kandy, Matale, Mawathagama, Madadumbara, Naula, Pallepola, Palvila, Pathadumbara, Pujapitiya, Raththota, Rideegama, Thumpane, Ukuwela, Yatawaththa
Vulnerability to drought/ flood
Boralu-Madabokka Complex, Boralu-Gampaha Association, Dodangoda-Boralu Association; Dodangoda-AgalawattaGampha Complex, Galigamuwa-Homagama Complex, Galigamuwa-Pallegoda Complex, Madabokka-Gampaha Association, Malaboda-Lithosols Complex, Malaboda-PallegodaDodangoda-Homagama Complex, Malaboda-WeddagalaPallegoda Lithosols Complex, Malaboda-Pallegoda Association, Maskeliya-Mattekele-Lithosols Complex, Palatuwa-WaguraMadabokka Complex, Pallegoda-Dodangoda-Homagama Complex, Pallegoda-Dodangoda-Boralu-Gampaha Association, Pallegoda-Dodangoda-Gampaha Association, Pugoda Series, Wagura-Palatuwa Complex
Boralu, Dodangoda, Agalawatta, Galigamuwa, Homagama, Malaboda, Maskeliya, susceptible to drought Gampaha, Pallegoda, Weddagala, Mattekele, not susceptible to drought Pugoda, Palatuwa, Madabokke, Wagura, susceptible to flooding
Divisional secretarial areas - WL1a Agalawaththa, Akuressa, Ambalangoda, Ambagamuwa Korale, Athuraliya, Aththanagalla, Ayagama, Ahaliyagoda, Alapatha, Elpitiya, Benthota, Bulathkohupitiya, Bulathsinhala, Dehiowita, Daraniyagala, Dodangoda, Dompe, Galigamuwa, Hanwalla, Horana, Kalawana, Karandeniya, Kiriella, Kotapola, Kuruwita, Madurawela, Mathugama, Meerigama, Mulatiyana, Nagoda, Neluwa, Niwithigala, Niyagama, Padukka, Palinda Nuwara, Pasgoda, Palmadulla, Pitabaddara, Rathnapura, Ruwanwella, Thawalama, Walallavita, Warakapola, Walivitiya Divithure, Yakkalamulla, Yatiyanthota
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Agro-ecological region Low Country Wet Zone - 1b (WL1b)
Low Country Wet Zone - 2a (WL2a)
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Vulnerability to drought/ flood
Boralu-Madabokka Complex, Boralu-Gampaha Association, Dodangoda-Agalawatta-Gampha Complex, MadabokkaGampaha Association, Palatuwa-Wagura-Madabokka Complex, Pallegoda-Dodangoda-Homagama Complex, Pugoda Series
Boralu, Dodangoda, Agalawatta, Homagama, susceptible to drought Gampaha, Pallegoda, not susceptible to drought Palatuwa, Madabokke, Wagura, Pugoda, susceptible to flooding
Divisional secretarial areas - WL1b Aththanagalla, Bandaragama, Benthota, Bulathsinhala, Dodangoda, Dompe, Hanwella, Homagama, Horana, Kaluthara, Karandeniya, Madurawela, Mathugama, Millaniya, Padukka, Walallavita
Vulnerability to drought/ flood
Beliatta-Okewela-Modarawana Complex, Boralu-Madabokka Complex, Boralu-Gampaha Association, Dodangoda-Boralu Association, Madabokka-Gampaha Association, MahawalatennaHunnasgiriya-Weligepola Complex, Malaboda-PallegodaDodangoda-Homagama Complex, Malaboda-WeddagalaHomagama Complex, Malaboda-Weddagala-Homagama Complex, Malaboda-Weddagala-Pallegoda Lithosols Complex, Negombo-Katunayake Association, Negombo-Puttulam Association, Palatuwa-Wagura-Madabokka Complex, PallegodaDodangoda-Gampaha Association, Ratupasa-Katunayake Association, Wagura-Palatuwa Complex
Boralu, Hunnasgiriya, Dodangoda, Homagama, Malaboda, Puttalam, susceptible to drought Okewela, Modarawana, Gampaha, Mahawalatenna, Weligepola, Pallegoda, Weddagala, Negambo, Katunayake, Ratupasa, not susceptible to drought Palatuwa, Madabokke, Wagura, susceptible to flooding
Divisional secretarial areas - WL2a Akmeemana, Akuressa, Ambalangoda, Athuraliya, Baddegama, Balapitiya, Bandaragama, Benthota, aberuwela, Bopepoddala, Dodamgoda, Galle, Godakawela, Habaraduwa, Hakmana, Hikkaduwa, Homagama, Horana, Kahawaththa, Kaluthara, Kamburupitiya, Karandeniya, Katuwana, Kasbawa, Malimboda, Mathara, Mathugama, Millaniya, Moratuwa, Mulatiyana, Nagoda, Niwithigala, Opanayake, Panadura, Pasgoda, Palmadulla, Pitabaddara, Walallawita, Weligama, Waligepola, Walipitiya, Waliwitiya Divithure, Yakkalamulla
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Agro-ecological region Low Country Wet Zone - 2b (WL2b)
Low Country Wet Zone - 3 (WL3)
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Vulnerability to drought/ flood
Galigamuwa-Homagama Complex, Galigamuwa-Pallegoda Complex, Kiruwana-Kurunegala-Batalagoda Association, Mawanella-Kandy-Kiribathkumbura Association, MinuwangodaGampaha Association, Pallegoda-Dodangoda-Homagama Complex
Galigamuwa, Homagama, Kurunegala, Minuwangoda, Dodangoda, Kiruwana, susceptible to drought Pallegoda, Batalagoda, Gampaha, Mawanella, Kandy, not susceptible to drought
Divisional secretarial areas - WL2b Alawwa, Aranayaka, Bulathkohupitiya, Galigamuwa, Kagalle, Kurunegala, Mallawapitiya, Mawanella, Meerigama, Polgahawela, Rambukkana, Warakapola
Vulnerability to drought/ flood
Aluthwewa-Hurathgama Association, Boralu-Madabokka Complex, Galigamuwa-Homagama Complex, KuruwitaKuliyapitiya-Kurunegala-Batalagoda-Assosiation, MinuwangodaGampaha Association, Negombo-Katunayake Association, Palatuwa-Wagura-Madabokka Complex, Pallegoda-DodangodaHomagama Complex, Pugoda Series, Ratupasa-Katunayake Association, Wagura-Palatuwa Complex
Aluthwewa, Boralu, Galigamuwa, Homagama, Kurunegala, Minuwangoda, Dodangoda, susceptible to drought Hurathgama, Kuliyapitiya, Batalagoda, Gampaha, Negambo, Katunayake, Ratupasa, Pallegoda, not susceptible to drought Madabokke, Wagura, Palatuwa, Pugoda, susceptible to flooding
Divisional secretarial areas - WL3 Alawwa, Aththanagalla, Biyagama, Colombo, Dankotuwa, Dehiwala-Galkissa, Diulapitiya, Dompe, Gampaha, Hanwella, Homagama, Ja-ela, Kaduwela, Katana, Kaleniya, Kasbawa, Kolonnawa, Mahara, Maharagama, Meerigama, Minuwangoda, Moratuwa, Narammala, Negambo, Nugegoda, Pannala, Thimbirigasyaya, Warakapola, Waththala
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Demographic data and vulnerability to drought and flood in provincial areas Central province
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Central province constitutes three administrative districts; namely Kandy, Matale and Nuwara-eliya district with a land area of 5674km2. It has 37 district secretariat divisions and 2186 of Grama Niladari divisions. The population of the province is 2.4 million with a population density of 667, 226 and 412 persons per km2 in Kandy, Matale and Nuwara-eliya districts respectively. The population density in Kandy district is higher than in other districts with exception of Colombo, Kalutara and Gampaha districts. The rural population is more than 80% in Kandy and Matale while in Nuwara-eliya percentage of estate population is 54%. Poverty Index of the districts according to 2002 estimates are fairly high; Kandy 25%, Matale 30% and Nuwara-eliya 23% which is higher than the national figure of 22.7%. With the exception of DL1b and DL1c agro-ecological zone (AER) other areas of the province either fall into intermediate or wetzone. Province is less prone to drought during maha season. DL1a and DL1c and all other AER in the mid country intermediate zone are prone to drought during the yala season. In contrast, all most all AER in the up country intermediate zone are less likely to experience drought condition during yala season. The major crops cultivated are paddy, vegetables, fruits, onion and potato among the food crops while tea among the plantation crops. Province contributes around 4% rice, 20% potato and 66% onion of the national production. Seventy percent of the tea acreage is found in the central province.
Eastern province Eastern province constitutes three administrative districts; namely Ampara, Batticaloa and Trincomalee and comprise with 9400km2 of land in which 3800km2 (nearly 40%) is under agriculture. Apart from the land under agriculture, 30% of the land in the province is still under forest and the rest is used for other activities. Paddy is the main crop and nearly 47% of the agricultural land is occupied by paddy which is capable of supplying 30% of the national requirement of paddy. Apart from paddy maize,ground nut, green gram, cow pea and red onions are the major other field crops growing in the province. Since the eastern border of the province is opening to the Indian Ocean, the province also contributes a considerable proportion to the fish industry in Sri Lanka. River mahaweli, the longest river of Sril Lanka, flows to the sea through Trincomalee district. Population in the eastern province is nearly 1.5 million of which 30% is directly involved in farming. Eastern province contributes 5.5% of the gross domestic product and it is 242,439 million rupees. (2008, Central bank report). Except for a small portion of the eastern province, area under province falls under low country dry zone and most of the land area is slightly undulating and becomes - 73 -
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flat towards sea coast. Based on this agro ecology and the land pattern several farming situations exist in the province viz rainfed or irrigated rice-rice farming systems, rainfed with supplementary irrigated rice - OFC system, rainfed with supplementary irrigated OFC-OFC and rainfed OFC system.
North central province
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The North Central Province (NCP) constitus two administrative districts, namely Anuradhapura and Polonnaruwa, both of which are of early historical relevance in the country. It records the largest land area of 10700km2 (16.3% of the island) with a population of 1.1 million, 5.91% of the nation. The NCP is bordered by Northern, North Western, Central and North Eastern provinces. The Ritigala, Sigiriya, Dambulla and Manewa rock hills are the main highlands. Four main streams flowing across the province are Kala Oya, Malwathu Oya, Kanadara Oya and Yan Oya. The largest number of reservoirs in the Island is found in this province among which reservoirs such as Kalawewa â&#x20AC;&#x201C; Balaluwewa, Rajanganaya, Padawiya, Huruluwewa, Parakrama Samudraya, Minneriya, and Kauduluwewa are considered as major water resources in the province. The province occupies entirely in the low country dry zone (DL). Total land area of the North Central Province is 9741sq.km while area under water bodies constitutes 731sq.km. According to historical records, the province has been affected by natural disasters such as drought, floods, epidemics, cyclones etc. Thus there is a considerable potential to affect the province by similar natural disasters which are being further aggravated by the current mismanagement of landscape, water resources and the soil resource. Exposed lands due to agriculture, building construction and road way construction are vulnerable to serious soil erosion and consequent land degradation. Flood prone areas are found along main streams such as Malwathu, Kala, Kanadara, Yan etc. in valleys and alluvial flat terrain landscapes in the NCP. Agro-ecologically the province comes under diverse micro-ecological zones of DL, which can be categorized into DL1b, DL1c, DL1e, DL1f, and DL2b. Soils in the DL1 region occur in a catenary sequence with the well drained reddish Brown Earths (RBE) on the upper and mid slopes of the undulating terrain, and the poorly drained Low Humic Gley (LHG) soils in the lower slopes and valley bottoms. Mean annual rainfall of North Central Province is less than 1750mm and it reflects a bimodel pattern. The most noteworthy cropping patterns include Rice-Rice, Rice-OFC / Vegetables and OFC-OFC cropping patterns. Rice is the main crop in the irrigated lowland. Altogether 121850ha of lands are cultivated under paddy of which about 116778ha are cultivated with the supplementary irrigation facilities provided by a vast array of well developed major and minor irrigation schemes while the rest is cultivated under total rain-fed condition. Average household size in the province is 3.8. Of total population 13.6% do not have the access to safe drinking water and a considerable portion of the population is vulnerable to urinary problems and kidney diseases. Per Capita Income (PCI) as estimated in 2008 for the province is Rs. 171,200 with PCI ratio of 0.8%. Gross Domestic Product (GDP) value computed in 2008 for the province is Rs. 206,990 mn and its growth has been found the highest (45.1%) compared to that of other provinces. That is a rapid increase from the value 21% reported in 2007. Further, agriculture sector accounts for Rs. 62,586 mn in the province indicating that there is a vast potential for further improvement in the sector.
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North Central Province has numerous potential for investors to initiate their businesses, specially in Agriculture, Agro-based Industries and Livestock Sector due to the expanding demand emerged in recent times for otherfield crops, particularly with relevance to maize, blackgram and big onion,. More than 65% of NCP people depend basically on agriculture and agro-based industries.
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The Northern Province consists of five districts, namely Jaffna, Killinochchi, Mannar, Vavunia and Mullathive. The total land area of the province is 8884km2 of which 8290km2 is land and 594km2 is water bodies. The estimated population of the province is 1.172 million and majority of them (51.5%) are living in Jaffna district. Agro ecological regions are DL1b, DL1c, DL1d, DL1e, DL1f, DL3 and DL4. There are about 69,000ha of paddy lands in the province and 57% is rainfed, 19% minor and 24% major irrigation. Majority (30%) of rice lands are in Killinochchi district and followed by 24% in Vavunia district. Most of the rice lands in Northern province is cultivated under rainfed situation. Average rice yields in the province vary from 2 - 3.4t/ha. Other field crops (OFC) are also grown in this province and the total extent is about 5,000ha. Maize, Cowpea, Groundnut, Millet, Mung bean and Gingelly are also grown in the province among which Groundnut and Mung bean are the main other field crops. These crops are basically grown under rainfed condition mainly during Maha season and the largest extent is at Mullathive district.
North-western province The North-Western province (NWP) of Sri Lanka encompasses two administrative districts, namely Kurunegala and Puttlam covering an area of 4816km2 and 3072km2 respectively (total 7888km2) with a total population of about 2.3 millions. The population density in Kurunegala and Putlem districts are 316 and 246 persons per km2 respectively. Kurunrgala is the capital of the NWP which has convenient access to all parts of the island with a very good net work of road within the province. With close proximity to international air port and Colombo harbor NWP has a huge potential for manufacture of export oriented agricultural as well as non-agricultural commodities. The agriculture sector is the major element of the economy of this province and has a considerable contribution to the national GDP, in particular, by paddy, other field crops and the plantation agriculture of Coconut, Rubber and Cashew. Yams, vegetables and leafy vegetable and fruits especially, pineapple and banana are also produced in large extent as commercial cultivation. Lime cultivation is prominent in drought prone areas in Putlem. A significant area of â&#x20AC;&#x153;kakulanâ&#x20AC;? cultivation of paddy is undertaken during yala season in Kurunegala district. The NWP has five major irrigation schemes, four in Kurunegala (Batalagoda scheme 2144ha, Magalla wewa 1879ha, Palukadawala wewa 888ha and Hakwatuna oya 1801ha) and one in Putlem (Tabbowa wewa 833ha). It has two major rivers; Daduru oya and Ma oya which have large catchment areas. Kurunegal district receives an annual average rainfall of 2400mm while Putlem receives only 1340mm.
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Kurunegala district covers four agro-ecological zones: IL1a, IL1b, IL3 and dry zone low country (DL1b). Putlem district consist of five agro-ecological zones, (IL1a, IL1b, DL3, DL1b and DL1f). Putlem district especially experiences agricultural drought conditions in this province.
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The Sabaragamuwa province encompasses two administrative districts, namely Kegalle and Ratnapura covering an area of 4,968km2 (Kegalle 1,692km2 and Ratnapura 3,276km2) with a total population of 1,926,000 comprising 380,000 families and number of farm families are 255,000.
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Arable land area of the provincial is 4,000km2 and flood prone area is 12.35km2. Elevation from mean sea level ranges from 18m to 2240m. Mean temperature ranges from 22.8oC - 32.8oC. This district contributes a considerable amount to the national GDP (Rs. 226,128 in 2007) through agricultural sector mainly by the plantations of tea (Ratnapura 36,763ha and Kegalle 10,128ha), Rubber (Ratnapura 39,908ha and Kegalle 51,952ha) and coconut (Ratnapura 11,828ha and Kegalle 22,740ha) Total paddy cultivated area of Ratnapura district is 17,324ha and that of Kegalle is 10,371ha. Considerable extent of Ratnapura district is under forest cover (74,260ha) including Singharaja. Forest cover of Kegalle district is 12,085ha. This province comes under diverse range of agro-ecological regions (16) of Dry, Intermediate and Wet zones namely DL1a, DL1b, IL1b, IL1c, IM2a, IM2b, WL1a, WL2a, WL2b, WL3, WM1a, WM1b, WM2a, WM2b, WM3a, WU1. Soil types are RBE, LHG, RYP, RBL, RBE, IBL, RBP, Lithosols and Regosols. South west Monsoon rains are highly effective in this province and hardly experiences agricultural drought conditions. However some areas mainly Ratnapura area experiences flood damages in each year during anytime of April to July.
Southern province The Southern province of Sri Lanka comprises of Galle, Matara and Hambanthota districts covering a land area of 5544km2 inclusive of 161km2 of inland water bodies. The province accounts for 8.45 percent of the total land area of Sri Lanka. The highest population is reported from Gall district and the lowest from Hambantota District. Much of the Southern Province (SP) has natural boundaries such as sea coast and rivers. It is a low country area bordering Indian Ocean. The area bounded by the sea coast is approximately 215 kilometers in length. The Bentota ganga and Kumbukkan Oya separates it from the Western and Eastern Provinces respectively. On the northern side, its boundaries are land areas of Western, Sabaragamuver, Uva and Estern provinces. The land type is generally flat costal belt and rolling terrain in the middle areas of the northern boundary (land side) of the Southern province. The province falls within the three main agro-ecological zones. About 48% land comes under wet zone, 5% in the intermediate zone and 47% in the Dry zone. Annual rainfall varies between 2500mm to 800mm from Wet to Dry zone areas in the province. Temperature variations in the province ranges from 20oC to 32oC in hilly area of northern boundary to costal dry zone areas. Relative humidity varies between 65-85% in the province.
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The Province is drained by seven medium rivers and 25 other small rivers. The coast is indented at frequent intervals by bays, river estuaries and inlets; the numerous inlets and the sea makes fishing an important coastal occupation. Red yellow podzolic soils are predominant in the wet zone while in the intermediate zone the red yellow podzolic soils, with strongly motted subsoil low in humic gray soil, reddish brown earth and immature brown loams predominate. The Dry Zone has reddish brown earth with a high amount of gravel in it. Southern province is a major agricultural province. Number of land holdings is around 460,211 covering an area of 259,279ha under different kinds of crops. The major crop cultivated in the province is paddy. Coconut, Tea and Rubber cultivations are the other main crops. The highest extent 25,000ha of Paddy cultivation is reported from Hambantota district while figures for Gall and Matara distinct are around 17,000ha. Large variation in the extent under paddy cultivation is observed in Yala seasons compared to Maha seasons. Mainly Cinnamon and Pepper are the dominant export agricultural crops in the southern province.
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Uva province The Uva province consists of two districts namely Badulla and Moneragala covering land extents of 2,818km2 and 7,133km2 respectively. The extent of the province is about 13% of the island. It is the second least populated province recording a total population of 1,187,335 persons. Of the total population of the country the province takes care of only 6.3%. Uva province is bordered by Eastern, Southern and Central provinces. The Gal Oya hills and the Central mountains are the main highlands, while the Mahaweli and Menik rivers and the huge Senanayake Samudraya and Maduru Oya Reservoirs are the major water resources. Inland water bodies cover an extent of 16,500ha of the Province and it is as small as 1.9% of the land area. Well known national heritages such as Dunhinda falls, Diyaluma Falls, Rawana Falls, the Yala National Park (lying partly in the Southern and Eastern Provinces) and Gal Oya National Park (lying partly in the Eastern Province) etc. are found within the boundary of the Uva province. The province occupies mainly in the low country physiograpic zone (LC), and spreads over upcountry and mid country zones as well with relatively low percentages. Agro-ecologically the province comes under diverse micro-ecological zones, which can be categorized into DL regions (DL1a, DL1b, DL1c, DL2a and DL5), IL regions (IL1c and IL2), IM regions (IM1a, IM1c, IM2a and IM2b), IU regions (IU2, IU3a, IU3b, IU3c and IU3e) and WU regions (WU3). This diverse environmental conditions lead to form various types of land use, wetness, seasons and floral and faunal compositions within the province. Further, the province is affected by natural disasters such as drought, floods, landslides etc., which are aggravated by mismanagement of landscape, water resources and the soil resource. Most dominant soil types of the Uva province are Reddish Brown Earths (RBE) associated with Low Humic Gley (LHG) soils in undulating terrains and RBE and Immature Brown Loams (IBL) in rolling, hilly and steep terrains. On hilly terrain and undulating topography, the surface soil has been eroded in many instances due to chena cultivation and quartz rich subsurface soil layer is present as surface layer. The LHG soil is widely recommended for paddy cultivation and for other crops. Precautions need to be taken for removal of excess soil moisture. The Uva Province has a diversified agro-based economy where income is generated from tea, paddy, vegetables, fruits, sugarcane, horticulture, pepper, grain cultivation etc. Most of the products are of a primary nature and hence do not fetch a better price in the market. According to the Department of Census and Statistics â&#x20AC;&#x201C; 2006/07, the highest poor household percentage (23.8%) is reported from the Uva Province. About 75,000 households have been identified under poor category. Average household size in the province is 4.1. Of total population 18.6% do not have the access to safe drinking water. This value is lower only to Central and Sabaragamuwa provinces. Per Capita Income (PCI) as estimated in 2008 for the province is Rs. 156,500 with - 83 -
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PCI ratio of 0.7%. Gross Domestic Product (GDP) value computed in 2008 for the province is Rs. Bn 202 and its growth has been found to be the lowest (14.2%) compared to that of other provinces. That is a rapid decline, about 45% from the value reported in 2007. Dry Zone areas especially in Moneragala district is frequently affected by drought. Exposed lands due to agriculture, building construction and road way construction are vulnerable to landslides in steep terrain areas. Flood prone areas are found along main rivers Mahaweli and Menik in alluvial flat terrain landscapes in the Uva Province.
Western province The western province of Sri Lanka encompasses three administrative districts, namely Colombo, Gampaha and Kalutara covering an area of 3,684km2 with a population of about 5.6 millions which comprised of 84.2% Sinhalese, 7.2% Tamils, and 7.1% Muslims and the rest belonging to other races. As both administrative and commercial capital cities along with country’s main airport, harbor and major industries are located in this province, it is the most populated province of the island with a density of about 1,456 persons per km2 with broad economic and social disparities. The service and manufacturing sectors are the major elements of the economy of this province and yet has a considerable contribution to the national GDP through agricultural sector, in particular by the plantation agriculture of Rubber (Kalutara district) and Coconut (Gampaha district). The extent under Tea, Rice and Other Field Crops in this province remained comparatively at a lower extent attributed to inherent unsuitability of soils of the region for those land uses except some fertile paddy tracts in the flood plains of Kalutara and Gampaha districts. Meanwhile, it is the least vulnerable province of the island for food insecurity with comparatively less number of people who live below the Lower Poverty and Higher Poverty Lines. Moreover, it claims the lowest Human Poverty Index of 14 in the Island whereas other provinces are ranged from 20 to 27. The western province has four major rivers with their catchment areas ranging from 736 to 2,719km². They are: Kelani ganga (2,292km²), Kalu ganga (2,719km²), Maha oya (1,528km²), Attanagalla oya (736km²). In almost all parts of the province, ground-water resources have been extensively used since colonial times for domestic purposes using shallow open wells but hardly for agricultural uses. As the entire province comes mainly under WL1a, WL3, WL1b and WL2a agroecological regions of the Wet zone where First Inter Monsoon (FIM), South West Monsoon (SWM) and Second Intermonsoon (SIM) rains are highly effective compared to other provinces of the island, it hardly experiences agricultural drought conditions. However, being located in the flood plains of aforesaid - 85 -
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countryâ&#x20AC;&#x2122;s four major rivers with higher upstream rainfall regimes in general, the province experiences the countryâ&#x20AC;&#x2122;s worst flood damages in almost all years, especially during anytime of April to July when the FIM and SWM are in full swing.
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CHAPTER - 3
CULTIVATION DECISION MAKING - 88 -
he Island experiances wide range of rainfall, temperature regimes, and soil conditions. Mean annual rainfall ranges from 900mm in the semiarid areas to 5,500mm in very wet areas. Elevation reaches up to 2,575m above mean sea level (msl) and the average temperature ranges from 15Â°C at the uppermost elevations to 30Â°C at sea level. Rice lands are distributed in almost all the 46 agro-ecological regions (Map 3), except at elevations above 1,200m, representing different soils types and hydrological conditions.
Up country wet zone paddy fields
Low country dry zone paddy fields
Based on rainfall, rice ecosystems in Sri Lanka are classified as Dry Zone (DZ) (rainfall <1,500mm), Intermediate Zone (IZ) (rainfall 1,500â&#x20AC;&#x201C;2,500 mm), and Wet Zone (WZ) (rainfall >2,500mm). While some of these paddy lands are cultivated under total rainfed conditions, others are being supported with irrigation facilities. Irrigated paddy lands are further classified as major irrigated (major) where the cultivated extent from the particular water source is more than 80 ha and minor irrigated (minor) in which cultivated extent from the particular water source is less than 80ha. Rice is cultivated in two distinct cropping seasons, Yala (dry season) and Maha (wet season), which are synchronized with the two monsoons.
Major irrigation tank (extent more than 80ha)
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In the past, rice had been cultivated as an upland as well as a lowland crop. At present upland Paddy cultivation is not practiced. The traditional local paddy varieties are naturally evolved and selected and are best fitted to up land environmental conditions. The up land Paddy varieties possessed very important characters for drought tolerance, though they produced relatively low yields. They were entirely rainfed and were cultivated either in low-lying area of the chena where water logging occurs during the rainy season or as an under-crop cultivation in lands in the intermediate zone. Conversely, lowland paddy varieties presently cultivated are mainly new improved varieties and are sensitive to water stress at their different growing stages. These critical stages are very important for preparing irrigation schedules, especially under dry weather conditions.
Eco system of other field crops Except for a very few number, almost all Other Field Crops (OFC) are grown under rainfed conditions in highland areas which represents the “Chena” lands as well. Highland means the areas located above the nearest water source that cannot be irrigated from the surface gravity irrigation system concerned. The farmers who cultivate these lands use either rainfall or lift irrigation to raise their crops. The highland rainfed farmers and “Chena” cultivators have very good understanding of the climatic conditions and adopt a cultivation calendar that is best suited to the climatic vagaries. With the expectation of rain in late September/ early October, they start land preparation in August/early September which are dry months. Seeding is commenced soon after initial rains that provide sufficient moisture to dry soil for seed germination. Vegetables that depends mainly on rain-fall receives from October to December, are also cultivated in the same time period. Non irrigatable land for other field crops
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Farmers who practice lift irrigation to supply water for cultivation mainly use two water sources, the ground water from agro-wells and the surface water (ponds, natural drainage lines etc..) which are located in lower elevation from the cultivated area.
Moisture stress on OFCâ&#x20AC;&#x2122;s In the dry zone, primary source of water is the rainfall which is received mainly from Northeast monsoon and the South west monsoon. The bimodal rainfall pattern leaves two distinct dry periods within the year. Annual crops are grown during these two monsoonal periods using the incidental rainfall. However, lack of adequate water very often encountered during the cropping periods is supplemented through irrigation facilities provided from the major and minor tanks in the area and this facility is mainly available for lowland rice cultivation. On the other hand, the highland crops are totally dependent on incidental rainfall in the dry zone, except for few crops that are grown under lowland rice fields with supplementary irrigation (viz. Onoin, chilli) during yala season.
Onion cultivation with supplementary irrigation (sprinkler)
Chilli cultivation with supplementary irrigation (flood/basin irrigation)
The shortage of water is a result of low rainfall or erratic rain fall pattern, poor distribution of rainfall, unreliable ground water supply and lack of perennial sources of water in this area. High wind velocity during south west monsoon together with high temperature supports a high evapotranspiration loss which subsequently leads into salinity development. As a result crops are subjected to stress conditions at various stages of - 91 -
Development of salinity due to extreme dry condition
their growth. Therefore, adoption of agronomic and other management practices to mitigate the water shortage has become important in dry farming situations. Established agriculture production systems in the past have been gradually changing with time, based on current climatic changes, agriculture development projects as well as needs and demands of the consumers and farming community. However, still we can recognize some typical characteristics, which have been inherited from the past, in the present farming systems. Small tank based agriculture environment, upland rainfed farming, irrigated lowland farming, agro-well based farming and home gardens are five prominent farming situations visible at present in the dry zone. Although farmers do not want to depend entirely on rainfed condition with the recent development of irrigation schemes, efficient means of water utilization should be adopted to avoid moisture stress conditions both on irrigated and rainfed arable lands. A majority of OFC farmers in the dry zone are confined to rainfed agriculture which is comparatively a less productive farming system. Among several factors, erratic weather and periodic biotic an abiotic stresses play a crucial role in declining productivity in the dry farming conditions. Thus a major determinant of crop production in dry zone is the availability of water. The farmers have to depend heavily upon the rainfall due to less availability of ground water resources and perennial water sources in the area. According to published information, annual rainfall in Sri Lanka has shown no significant increasing or decreasing trend except for few locations but its variability has shown a clear increase during recent decades. As a result of these convincing variabilities in monthly rainfall distribution during yala and maha seasons, there is a high probability of encountering unexpected drought situations at different stages of the crop growth.
Consequences of moisture stress The cultivation of field crops under rainfed agriculture in the dry zone is confined to Reddish Brown Earth (RBE). RBE soil is extremely hard when dry, friable to firm when moist, and sticky when wet. Both extreme conditions cause difficulties in tillage operations such as ploughing, weeding, earthing up etc. This condition becomes critical when there is a high variability of climate. Extreme rainy as well as the dry conditions make land preparation difficult in RBE soils. Further, high temperature coupled with low rainfall will increase salinity development in arable lands causing a significant influence on OFC, particularly, on Agro-well farming - 92 -
Reddish brown earth is extremely hard when dry, friable to firm when moist and sticky when wet
and lowland OFC cultivation. Besides, warmer conditions are likely to speed up the microbial decomposition of organic matter which may inturn reduce the water holding capacity in soil. High temperature also causes changes in insect pest population dynamics resulting sudden pest outbreaks.
Undulating terrains in dry zone
Most of the areas in the dry zone have slightly undulating terrains that will not permit rapid drainage flow with high intensity rains which are common with monsoon, and inter-monsoon rains. Therefore, most of the perennials and the other field crops suffer water logging conditions even in the well drained areas if the drainage network is not properly in place to take the excess water out from the agricultural area. The critical growth stages of existing long age varieties of OFCs are affected both by high and low moisture stress. Hence it is important to take appropriate measures to mitigate the adverse effects of soil moisture at both extreames for unimpeded crop growth. The amount of rainfall received in the maha season would decide the type and extent of both maha and yala cultivation. Consequently, less availability of water in minor and major irrigation tanks would limit cultivable land area under each tank. This would lead into a Bethma cultivation system where cultivable extent for each individual farmer is reduced and this would inturn lead in to broaden the poverty of the rural farming sector. - 93 -
Independent water source user
Correct cultivation decision making is the most important factor in water management process as all the water management operations depend on this factor.
Cultivation decision making 1. Independent water source users 2. Common water source users
1. Independent water source user If you are an independent water source user (rainfed farmers, many wet zone farmers) you can make your own decision with the confidence you have about your water source. Rainfed cultivators all-over the country has a fix cultivation time table prepared by them using traditional knowledge. The farmer practices are different among the farmers in wet and dry zones.
i. Wet zone rain fed farmer Paddy cultivation in the wet zone of Sri Lanka is mainly under rainfed or diversion systems. Under normal weather conditions, sufficient runoff is collected in the watercourses throughout the year and therefore there is no need to keep water stored. Wet zone farmers directly divert water from the watercourses to their fields. They have good understanding and knowledge about the behavior of stream flow. In many cases, farmers individually make their own cultivation decisions because collective actions are not much required for irrigation in these systems where water is used by one or a few farmers. If considerable number of farmers use same water source (common resource users) they have special institutional arrangements for decision making and sharing water. Wet zone rainfed farmers use direct rainwater and rainfall runoff collected in to local drainage lines for their cultivation. Most individual farmers has own streamlet for their field in wet zone. They do not keep any records on rainfall or water use. Individual farming method has little difference when compared to the government managed systems in which system managers keep records as a part of their duty. - 94 -
ii. Dry zone rainfed farmer Dry zone of Sri Lanka has a binomial seasonal rainfall pattern interspaced by long dry periods. Normally length of the rainy periods does not match with the length of cultivation periods in the dry zone. Therefore, rainfall runoff is stored in tanks during the rainy period for the use of crops at a later stage. Our ancestors built tank reservoir system in the dry zone for this reason. Inflows to the reservoirs depend on the amount of rains received in the season. Seasonal rainfall varies largely among the seasons. Water storage in the tanks is not sufficient to cultivate entire command area under the tank in some seasons in which rainfall is low. In such circumstances, predicting the inflow pattern based on the anticipated rainfall is very important for making cultivation decisions. The traditional villagers are said to have such a prediction system based on nature, especially blooming and flowering of some trees etc. However these predictions have not been scientifically validated. Rainfed cultivation starts with initiation of Maha season rainfall and most of the farmers use water from direct rainfall and moisture stored in the soil to raise vegetables and other field crops in highland areas. Lowland areas are mostly cultivated under irrigation facilities of minor (small) tank systems. Rainfed highland farming in the dry zone had been practiced in the past as “chena” or slash and burn cultivation. Now the authorities do not allow farmers to open virgin forests for “chena” cultivation. Hence farmers are been forced to continue upland farming in the same land which has been already cleared for rainfed cultivation. Most of the farmers use to settledown on these lands and after which they are been referred as homesteads. In this chapter we discuss general cultivation decision making and planning process under normal weather condition while decision making under extreme weather condition are discussed in Chapters 4, 5 and 6.
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Decision making Matrix for independent water source users a. Predicting anticipated climatic condition for the coming season Farmers always expect general pattern of climate for them to engage in cultivation. If you observe the past and guess the future, based on your experience, you can prepare to face the challenge. Water is the most critical factor for cultivation. Water shortages lead to yield drop and sometimes to crop failures. Floods may destroy the entire cultivation in few hours. It is very important to identify these conditions well ahead of time and be prepared for uncertain situation.
Memorize last season
Memorize season before last season
Memorize when did the last draught occur in your field area
Refer in to scientific information
How do you categorize last season; 1. Extreme wet (floods) 2. Wet 3. Normal (Average) 4. Dry 5. Extreme Dry (drought)
How do you categorize season before last season; 1. Extreme wet (floods) 2. Wet 3. Normal (Average) 4. Dry 5. Extreme Dry (drought)
1. 2. 3. 4. 5. 6.
Last season Before last Three season before Four seasons before Five seasons before Not in recent seasons (last 10 seasons)
If you have access to internet ( from your home, Agrarian Service Center, Vidhata Center or Nanasala) in your area Visit to Metrological Department website now available for countrywide forecasting. http://www.meteo.gov.lk/Non_%20Up_Date/pages/ agriculture.htm.
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What would be the next (coming) season
How do you assess next season
According to the above assessment
Consider your divisional secretarial area in the Chapter 2 and decide anticipated climate in the coming season.
1. 2. 3. 4. 5.
Extreme wet (floods) Wet Normal (Average) Dry Extreme Dry (drought)
Are you ready for cultivation under the climatic conditions you assessed above? Yes/ No.
b. Assess water source Water source is important for cultivation decision making. To minimize risk of water shortage, proper planning can be done about cultivation and prepare to face the problem. Also can prepare for alternative or conjunctive uses.
When you are going to start cultivation, do you have sufficient water to complete cultivation? (Yes/No) If Yes, go for your usual practices. If No, go to No.2 below.
What are the alternative sources that can be used?
Adopt water conservation practices
Reduce cultivation extent
Go for low water requiring crops
1. Assess water availability on crop growth stage. 2. Availability of equipments (pumps etc.). 3. Evaluate the competitive users that can be a threat for irrigated agriculture (domestic uses farm animals etc.).
1. Select suitable irrigation interval depending on crop growth stage and soil type of your land. 2. Use agronomic practices to reduce water demand.
1. If water availability does not match with your farm land water requirement, reduce cultivation extent of the intended crop or go to No.5 below.
1. Change from high water required to low water required crops (from Paddy to OFC) (Table 2). 2. Use drought resistant varieties for cultivation, though yield are low, market price will be high. - 97 -
Table 2: Water requirement of different crops for DL1b zone. (Low country dry zone - 1b) Crop
Crop duration (days)
Water requirement (mm) Yala Maha
Paddy Paddy Paddy Chilli Big onion Maize Sorghum Soya bean Greengram Cowpea Pulses Grount nut Sun flower Beans Cabbage Carrot Cucumber Brinjal
135 105 80 150 95 115 1 40 105 75 90 90 110 130 90 120 100 130 130
1650 1250 1000 920 700 825 1075 710 460 770 560 735 830 530 - - 790 825
1180 910 750 590 460 610 390 245 370 300 395 460 310 445 330 490
Radish Tomato Banana
60 135 330
200 490 1565
Source: FCRDI, Mahailluppallama
Actual field water requirement for the crop will vary from place to place (due to changes in crop evepo-transpiration) and soil type.
If water source assessment does not match with your farm water requirement Keep land fallow and save the money and seed material for the next season.
c. Selection of type of crop Total water demand varies according to type of crop. Water requirement of some crops are higher than that of others. If seasonal water availability does not match with intended crop you will not be able to get the desired yields. Therefore select the correct crop at the initial planning stage.
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Intended crop to cultivate
Are you satisfied with water demand and expected availability of water for intended crop? Yes/ No.
Use recommended cultivation practices of DOA.
Consider next best crop to suit for the condition with input availability and marketing possibilities in consideration. If you can sign a forward sales contract with agri-business enterprise to dispose your harvest, go ahead.
d. Readiness of inputs Some farmers are not ready to start cultivation with the on set of rain (just after sufficient moisture is available in the field). Late farmers always face dry weather conditions affecting their crop towards the end of the season or heavy rainy period in the every season itself before the crop is properly established. Timely cultivation always leads to a success. For this, you must pre-plan and organize your resources to start cultivation with the onset of rains.
Keep inputs ready
Do you have Sufficient Seed material
Plan your cultivation calendar and keep all inputs ready for use at correct time. If you are not organized farm machinery, labor, seeds, fertilizer and required credit (financial) facilities in advance, you will loose considerable amount of moisture due to delays and some times it may lead to crop failure also. Keep inputs arrange in advance.
Keep seeds of whatever variety you decide to grow ready. Use good quality seeds/ produced by you if possible or get registered/ certified seeds from authorized persons.
Depending on the soil fertility of your field, fertilizer application will vary. Normally fertilizer is applied as Basal application just before crop establishment when soil has some moisture level. Fertilizer Top dressing1 and Top dressing â&#x20AC;&#x201C; 2 are also applied for most crops depending on your soil fertility. - 99 -
Do not drain out the rain water if it is not in excess, let it to infiltrate in to soil and apply fertilizer when soil moisture level is applicable. If you are expecting heavy rains in next two/ three days period, do not apply fertilizer to the field.
Many farmers waste water when they do crop management practices like weedicide, pesticide or other agro-chemical application. Do not drain-out water un-necessarily for crop management activities. Plan activity with consideration for water saving for the crop and maximum utilization of chemical you apply.
e. Commence of cultivation (time of planting) Rainfed farming entirely depends on incidental rainfall. If you are not ready for the season and start activities in timely manner, you may face with either water shortage due to poor rains or crop damage by heavy rains. Timely actions can maximize water productivity and lead to successful completion of cultivation. Since water is the critical factor for rainfed farming, farmers must use their past experience on cultivation on the concerned field because it is a location specific nature.
Are you cultivating the field on Yala and Maha seasons without any water problem? Yes/ No
Cultivating same type of crop on both season
Cultivating different type of crop in each season
If Yes, both season same type of crop or different crops. If No, what kind of water problem - Shortage/excess.
If paddy is cultivated in both seasons, based on your experience, adhere to normal cultivation calendar for the year. If you are doing OFC or Vegetable crops in both seasons, consider best planting time according to crop and water availability of your location.
If you are cultivating Paddy in Maha season and other field crops in Yala season - You can start cultivation early in Yala season, just after Maha harvest. If sufficient residual moisture is available in the field. Before starting Yala cultivation you must analyze the climatic condition as mentioned early. This will ensure some harvest if the weather pattern go dryer than normal.
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2. Common water source uses (public systems)
The farmers using common water source (small/ minor tank, major irrigation system, and diversion/ anicut system) are considered here. Unlike independent water source users, deviated action of one user has some impact on the other users who are sharing the same water source. Working on commonly agreed cultivation plan is very essential to get maximum benefit of water in case of the common source. For this all the users under the water source must come under one institute or organization to use water fairly and efficiently. The reasons for most cultivation failures in public irrigation systems are mainly due to un-organized decision making and actions.
Decision making matrix for common water source users a. Farmer organization (FO)/ Water user association (WUA) (Here FO and WUA are refer to same institute) Unorganized actions on common resources by the group of farmers leads to waste the water resource. To get maximum benefit of limited water resource, assemble the user farmers in to appropriate institution for planning, decision making and operation of the system.
Common water source
Public system must have some user friendly control and operation mechanism to avoid anarchism or rigid management. Participatory Irrigation Management (PIM) help farmers and officers together to plan and implementation of the actions. Systemic decision making process under PIM leads to mutual understanding of the situation and information exchange. - 101 -
Are you a regular farmer under this irrigation system? Yes/ No If Yes, go to No.2 below. If No, meet some officers and famers in the irrigation system and discuss with them about the management of the system. Discuss how you can fit in to the system casually and your role.
Do you have FO for your irrigation system? Yes/ No If Yes, go to No.3 below. If No, Meet your APRS (Agriculture Research and Production Assistant), AI (Agricultural Instructor) or irrigation authorities for more information on FO/ WUA.
Are you a member of the FO? Yes/ No
Is the FO meeting regularly? Yes/ No
If Yes, go to No.4 below. If No, join to the FO and be a active member.
If Yes, go to No.5 below. If No, encourage FO office bearers to hold FO meetings regularly and discuss seasonal planning (next season), current operational problems if any/ improve water Management.
Do you participate at pre_Kanna and Kanna meetings? Yes/ No If Yes, go to No.6 below. If No, Please participate at the next meeting. It is very important to know the cultivation decisions and the status of the system. Very important issues like how the system operates in the season are discussed in this meeting. It is very important to know all these decisions to plan your cultivation activities for saving water.
Do you agree with the Kanna meeting decisions and work accordingly? Yes/ No If Yes, it is very good. it will benefit to the members also and able to save lot of water, when you work cooperatly and closely with FO members. If not, your actions related to cultivation may have some negative consequences to the other members of your irrigation system. If you are a late cultivator or cultivate non agreed crops in the Kanna meeting and violate the agreed irrigation schedules for the season, it may lead to system level failure of the crop due to water miss management. So donâ&#x20AC;&#x2122;t disagree with common decision; you may have some personal reasons, but it is better to respect to the common decision and act accordingly as you have a social responsibility.
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b. Behavior of water source in the past Most irrigation systems in Sri Lanka are unable to keep cropping intensity at 200% per annum. Even they are not operating maximum potential level because of poor cultivation planning. It is important to identify the trend of water source behavior when planning cultivation season. Very often there wonâ&#x20AC;&#x2122;t be sufficient storage of water in the water source for the successful completion of cultivation. Always farmers expect the balance anticipating as inflow to the water source. It is very important to assess correctly the future weather conditions and trend of storage behavior for the cultivation planning.
Do you have some storage data (time series data) for your water source? Yes/ No If Yes, go to No.2 below. If No, in the FO meeting, go back to memories of memberâ&#x20AC;&#x2122;s, documents on last season water source behavior and important incidences and then repeat the same as you did about seven/ eight previous seasons. Highlight when did you face last drought/ flood mark on time series line diagram. This will provide you some idea about behavior of your water source over the past.
Did anyone analyze, plot or made charts from this data? Yes/ No If Yes, go to No.3 below. If No, most irrigation system managers collect very important data as a routine job, but they do not analyze these data and donâ&#x20AC;&#x2122;t use the information as decision support tool. Do simple analyzes like how much total irrigation water has been used for the season, how much contributed by RF, length of land preparation period, length of cultivation period, irrigation period and rotational water supply, crop and yield ..etc.. At least data must be analyzed for the past 06 seasons and plot or arrange on a table for use as decision support tool.
Are you using this outputs for cultivation decision support tool (observing past trends) Yes/ No If Yes, good. Others also can easily understand the situation, individuals will give their views on the reasons for variations. If need it can keep under attention or take action if required. If No, present and discuss these results in the pre-Kanna and kanna meetings. Farmers will easily understand and any doubts they are confronted and those, can be scientifically explained using these results. This will help to get solid decisions on cultivation. - 103 -
c. Prediction of Climatic conditions Unlike independent water sources users, public water sources users (small/ minor irrigation systems and medium/ major irrigation system) are coming under supervision/ management of Department of Agrarian Development and Production (DADP) or Department of Irrigation (ID) or Mahaweli Authority of Sri Lanka (MASL). Normally field technical officers under these agencies collect and maintain climatic data in the area of their authority. Many irrigation systems in Sri Lanka have at least rainfall data at all respective locations. This information and the Indigenous Knowledge (IK) on predicting climatic conditions (see Chapter 8) can be used for predicting climatic conditions for the coming season. All our tank storage and diversion anicut systems depend on rainfall runoff water flowing in natural drainage systems and most of these systems are not able to store or assure full seasonal requirement of water for the command area. Mostly in the Maha season, they get enough runoff to meet the seasonal water requirement for full scale cultivation. While some times, some water is left behind for next season. Very often water problems are encounted during Dry Yala seasons impending the successful complete cultivations. Because of the less amount and short duration of rainy period followed by long dry period, proper identification of the season at the beginning is very important. In large irrigation systems and trans- basin augmentations, decisions are taken under Participatory Irrigation Management (PIM) by Project Management Committee (PMC) comprised of technical officers and farmer representatives. Many views are discussed in these meetings and all the factors are considered before taking final decision for cultivation. Assume what kind of situation has to be faced in the coming season and how to get ready for this situation. Predict climatic condition in the coming season by observing past weather records and trends. Indigenous Knowledge (IK) on predicting climatic condition also useful as this would minimize their financial losses. If your system does not support with facilities for augmentation, it is vital to identify those in the coming season. Most farmers depend on loans to invest for cultivation. If the season fails, it will be big loss for their economy. If you have a doubt about the season, discuss with other members and draw a common decision about cultivation.
Do your PMC/ FO discuss about climate of the coming season? Yes / No If Yes, see No.2 below. If No, you can meet technical officers/ farmer representatives to present your views and draw their attention to discuss the climatic factors at PMC/ FO meeting.
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Do they base on past records and information? Yes / No If Yes, go to section â&#x20AC;&#x2DC;dâ&#x20AC;&#x2122; below. If No, discuss with them and get clarified how those were decided. Discuss with other members to have their views in this regards.
d. Current status of water source (availability) After the previous season, if sufficient water is available in the water source and the assessment of climatic conditions for coming season are favorable, then the farmers can get ready for timely cultivation. Most of them use to start cultivation after required quantity is collected in the water source. By this time, considerable amount of moisture received by direct rainfall may have lost without using it productively. If you correctly assess the climatic conditions and water situation, plan to start cultivation activities early with the onset of rains to save water as much as possible in the water source. When the rain delays, sufficient quantity of water required for a week or two must have in the water source, to start cultivation. All the users must be informed, about status of water source at the beginning of the season.
Are you aware about current status of your water source? Yes/ No If Yes, go to No.2 below. If No, discuss with your neighbor farmers, farmer representation and relevant water managing officials on the state of water source. You must keep your interest to get information about your water source throughout the season.
Do you think the present status of your water source is sufficient to start the season? Yes/ No If Yes, get ready for field activities as discussed in PMC/ FO meeting If No, discuss your views with others and share ideas. If their explanations and points are reasonable and valid, you must accept these and work in common agreement.
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CHAPTER - 4
BEST CROP MANAGEMENT PRACTICES FOR DROUGHT BEFORE CULTIVATION - 106 -
Paddy fields in central highland
Water use in rice cultivation
ice is a semi aquatic plant. Water productivity of rice varies from 0.2 to 1.2g grain per kg of water depending mainly with the location having different evaporation values, growth stage and age class of the crop (Table 3). In addition to crop water use, water is needed for land preparation and for natural drainage as seepage and percolation, when rice is cultivated. Water use of rice crop in yala season is 4.7, 3.6, 3mm/ day in dry zone, intermediate zone and wet zone respectively. In maha season, it is 3.0, 2.7, and 2.6mm/day in dry zone, intermediate zone and wet zone respectively. Average amount of water needed for land preparation is approximately 250mm for clay soil while 300mm for soil having less clay. Water removed from the well drained soils is around 6 mm/day while 3mm/day from the poorly drained soils. Table 3: Estimated crop water requirement (mm) for different age classes of rice. Age class
Yala DZ IZ WZ
4 3 3 2
1550 1475 1425 1375
months Â˝ months months Â˝ months
1425 1375 1325 1275
1350 1300 1275 1225
1350 1325 1275 1225
1325 1300 1250 1200
WZ 1325 1275 1250 1200
In lowland irrigated rice system, continuous flooding which is normally practiced by farmers provides the best growth environment for rice. After transplanting water level should be around 3cm initially and gradually increase to 5-10cm with increasing plant height. - 107 -
In direct wet seeding, the soil should be kept just at saturation from sowing to 10 days after emergence, and then the depth of ponded water should gradually increase up to 3cm with increasing plant height.
Soil just at saturation from sowing to 10 days after emergence
3cm depth of ponded water after 10 days
In direct dry seeding, the soil should be moist but not saturated from sowing till emergence or else the seed may rot in the soil. After sowing, apply a flush of irrigation if there is no rainfall to wet the soil. Saturate the soil when plants have developed three leaves, and gradually increase the depth of ponded water with increasing plant height. With increasing water scarcity, water management practices during the whole growing period need to be considered. Instead of keeping a 5-10cm depth of standing water during the growing season, the depth can be reduced to around 3 cm. This will reduce seepage and percolation losses. Lowland rice fields are extremely sustainable and produce continuously high yields, even under continuous double or triple cropping in every year. Flooding of rice fields has beneficial effects on soil pH, soil organic matter buildup, phosphorous, iron and zinc availability, and biological nitrogen fixation.
Selection of age class to fit the rainfall and water availability Selection of an age class to suit the amount of available water would increase field irrigation water-use efficiency. In general, lowering the age class of rice grown decreases the water requirement for paddy and minimize the potential exposure to drought as a result of reducing crop maturity duration. However, there is only a small decrease in the fertilizer and pesticide use in short duration varieties when compared with long duration varieties. Cost of land preparation and other agronomic practices would be same for all varieties irrespective of their maturity period. During maha season, it is advisable to cultivate 3 Â˝ month varieties in irrigated rice ecosystems in the dry zone, while during yala, it should be 3 - 108 -
month varieties. Cultivating 4 – 4 ½ month varieties are not advisable as the value of additional water required for cultivating long age rice is not justifiable. For the intermediate zone rainfed system, there is a possibility of cultivating 3 ½ month crop during maha season while either 3 month or ultra shortage varieties should be cultivated in yala season. Ultra short-duration (80 days) variety (Bg 250) could be used in drought-prone areas to avoid terminal drought. The potential yield of such varieties in terminal drought prone areas is around 3-4t/ha where no yield could be obtained with longer maturity varieties under such situations. These varieties could be adopted as a drought escape mechanism.
Crop management practices for lowland irrigated rice system a. Time of starting field operations
Risk of drought can be minimized by adjusting the time of crop establishment to avoid sensitive crop growth stages during water deficit periods. Optimal time of cultivation has been considered as an important step in maximizing economic yield while optimizing resource-use efficiency. In Sri Lanka, cultivation seasons have been designed to complete all harvesting operations of rice during the driest months, February/ March, for the Maha season and August/ September for the Yala season. However, most of the farmers do not adhere to optimum timing due to various avoidable and/ or unavoidable reasons. During the Yala season in the major irrigations schemes of the DZ the window of initial operations (land preparation and seeding etc.) of a given rice track is very long and spanned from late March to mid-May. Conversely, in the IZ and WZ, the window for initial field operations during yala season is comparatively shorter than that in the DZ. However, the cultivation window during maha season is very long in all DZ, IZ as well as WZ. The availability of water either from irrigation or rains largely facilitate farmers’ operations. Rainfall is an important factor in deciding the time of
Paddy fields in low land (Hambanthota district)
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planting in the rainfed ecosystem. However farmers in the DZ with assured supply of irrigation water, waite for the irrigation water and seldom start operations with the onset of monsoon. Initial land preparation with the onset of rains, not only conserve irrigation water but also help to plow deep into the soil and facilitate growing a longer duration rice crop without exposing it to terminal drought. Even an individual farmer who wanted to start his field work with the onset of rains is reluctant to do so as field operations are begun in groups in a rice tract. A delay in initial land preparation until impounding of irrigation water increased water use while reducing yields because of planting of short-duration varieties. Further, a delayed crop carried the risk of increased seedling pests and terminal drought. In the Intermediate Zone, where availability of irrigation water is scarce, farmers are compelled to start operations with the onset of rains. Further, initial land preparation with the onset of rain breaks the capillaries created by the decaying roots of the previous season preventing seepage to a greater extent, facilitating stagnation of water for subsequent field operations. If not, stagnation of water in the paddy field is possible only when the water table reaches up to the soil surface. Therefore, timely cultivation with maximum use of rain water has a tremendous potential for increasing rice production while maximizing irrigation water-use efficiency.
b. Land preparation
Cleaning and plastering of bunds
The method of land preparation and sowing of seeds varies with soil type, location, season, and farmersâ&#x20AC;&#x2122; attitude. Land preparation and the subsequent method of establishment of rice in Sri Lanka are followed under complete dry, semi-wet, wet, or initial dry and subsequently wet conditions. A majority of farmers prepared land under wet conditions.
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Ploughing without sealing rat and crab holes leads to wastage of water
The primary objective of cleaning bunds is to reduce weed flora on the bunds and incorporate residues with soil but subsequent plastering with mud prevents lateral seepage of water. Further scraping of bunds to remove weeds expose rat and crab holes allowing farmer to plug them.
The time taken for land preparation could be minimized to about 2 weeks using total herbicides, which also helps to reduce tillage operations by one and conserve irrigation water.
Water use is highest during land preparation. Therefore, land preparation with a minimum time and maximum use of rainwater at the correct time of the season is desirable not only for attaining optimal rice productivity but also for increasing water productivity. - 111 -
c. Crop establishment Farmers adopt different methods of direct-seeding and associated agronomic practices in rice cultivation in Sri Lanka because of variation in water availability, soil type, cultivating season, and socioeconomic status. Methods of land preparation and cleaning of bunds, pre-germination of seeds, sowing of seeds, impounding water in the field, weed and fertilizer management options, etc., vary among different rice agro-ecosystems.
Low land/rainfed rice system Rainfall is the critical determinant of the productivity of this system. Amount and the distribution of rainfall determine the rice cropping season. Because rice is more sensitive to water stress, distribution of rainfall is more important than total seasonal rainfall. The beginning and end of the monsoon varies each year. The intensity of bimodal peaks varies and the degree of dryness between the peaks determines the suitability of cropping patterns. In rainfed lowland/ upland rice system, it is necessary to conserve soil moisture and to increase water use efficiency. There are several soil management techniques and cultural practices for conserving soil moisture in rainfed rice fields.
a. Land preparation This varies greatly depending upon rainfall pattern and soil type. In certain areas where water is a problem and when the onset of rain is delayed, farmers practiced dry land preparation. In the past, to ensure collective and timely cultivation, farmers organized ceremonies to mark the onset of the season. These traditional practices reduced the period of land preparation in a given track and conserved a significant amount of irrigation water. Methods of land clearing and development influence soil structure, pore size distribution, and infiltration capacity and therefore the water availability for crop growth.
Dry land preparation
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Mulching Crop residue mulch and dry soil mulch are used with varying success to reduce runoff and conserve soil moisture for rainfed rice cultivation.
Cover crops planted at fallow Fallowing with legumes rapidly improve infiltration in degraded soils.
Deep tillage Deep plowing conserves moisture by killing weeds and permitting greater water absorption. Deep plowing facilitate development of deep and extensive root system which in turn help absorb water from a larger volume of soil.
Zero tillage Minimum or zero tillage conserve energy during land preparation and does not disturb soil while retaining soil physical conditions. Zero tillage increases soil fertility and organic matter content. Enhancing organic matter content increase availability of soil water. Zero tillage should be practiced only in deep soil where plow layer is below 12” or more, especially in bog or half bog soils.
b. Crop establishment It is best to sow rice under rainfed conditions when the monsoon begins. Early planting assures longer rainfall duration from seeding upto grain filling. Late planted crops may suffer from periodic droughts. Broadcasting is a common practice on lands prepared dry or wet condition.
Direct dry-seeding Seeds can also be sown as ungerminated dry seeds. In this method, dry seeds are sown into dry soil either in rows (very rarely practiced) or at random. An additional advantage of dry seeding is the early establishment of the crop which may allow farmers to grow an extra crop after harvest with residual soil moisture or using saved irrigation water. In purely rainfed systems, early establishment and harvest of dry seeded rice allows the rice plants to escape any late season droughts and hence improve the yield and its reliability. Dry-seeding is practiced in less than 5% of the total rice area, mainly in rainfed ecosystems during the minor season and in the eastern region of the Island. Dry seeding is usually known as either “Kekulan” or “Manawari” cultivation. There are differences between the two systems. Kekulan cultivation is done mainly in sandy soils in the middle and western region of the country in both Maha and Yala seasons when the onset of monsoon rains is delayed, while manawari is practiced as a tradition in the eastern region of Sri Lanka during the Maha season.
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Kekulan cultivation Kekulan cultivation is possible only in sandy clay soil where dry land preparation is practicable. When the onset of monsoon is delayed, especially during the Yala season, kekulan farmers plow fields under dry soil conditions. Plowing is done by 2- or 4-wheel tractors or with buffaloes. The use of buffaloes for land preparation has declined because of their unavailability. If initial weed density is very high, systemic herbicide, glyphosate at 3L/ha or contact herbicide paraquat at 4–6L/ha, are applied to reduce drudgery and to kill weeds. This sometimes reduces the number of field operations before sowing. Under dry conditions, shallow plowing is practiced and depth does not exceed 8–12cm. Subsequently, bunds are cleaned; all shrubs and tree branches shading the rice field are lopped off and distributed over the field. About 1–2 weeks after the first plowing and clearing of bunds, when plant debris is almost dried, hard branches and other debris are removed from the field. This is followed by harrowing to break big soil clods using the same animal-driven plow or tractor-mounted tine tiller or rotovator. Thereafter, dry seeds are sown and seeds are mixed into soil by breaking big soil clods using a mammoty or tractor-mounted rotovator or tine tiller. To compensate for poor germination and to smother weeds, most farmers use higher seed rates of about 150kg/ ha. A few farmers spread rice straw onto dry-seeded fields to
Conserve soil moisture Prevent bird damage Avoid wetting and drying of seeds Keep from exposing seeds to direct radiation
These practices enhance seed germination. However, there is a risk of introducing rice seeds of an unwanted variety from rice straw.
Because of high risk, farmers who practice dry-seeding are reluctant to invest in the rice crop at initial stages. High-quality seed is not used in kekulan cultivation. Seeds from the previous season or borrowed from neighbors are used as seed paddy. No basal fertilizer is applied. However, with the onset of rains, fertilizer (mostly N and K) is applied. The total time period for these operations does not exceed 2 weeks. Some farmers do all operations within a very short period, often in 2–3 days after the first plowing. A good uniform crop is expected if rains come in time after sowing and continues with low intensity. - 114 -
Manawari cultivation Unlike farmers who practice Kekulan cultivation particularly in Kurunegala district during yala season, farmers in the eastern region of Sri Lanka practice dry-sowing every year during the major rainy season, the Maha season. This practice is called manawari cultivation. Normally, crop establishment under this system is completed before the onset of intermonsoonal convective rains, which begin in September. All farmers in these manawari paddy tracts collectively cultivate rice under dry conditions. Depending on the timing of the onset of low-intensity initial rains, seeds germinate. With this practice, farmers in this region conserve irrigation water to be used during the succeeding dry Yala season. Compared with kekulan tracts, manawari tracts are fairly extensive .
Usually, all operations are done using 4-wheel tractors. Little or no organic material is available as soil amendments. Residual soil fertility from the previous season is used to raise the crop until fertilizer is applied along with the onset of rains or with irrigation. The major difference between kekulan and manawari systems is that the latter is practiced only in the Maha season, while the former during the dry Yala season. With the availability of water depending on germination and weed density, thinning or gap filling is done in kekulan fields but never in manawari cultivation because of the large field size. This is one of the reasons for using a very high seed rate, around 200â&#x20AC;&#x201C;250kg/ha, in the manawari system.
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Decision making matrix for drought condition before cultivation season start If the drought condition prevails before the normal time of cultivation, climatic condition and water situation need to be assessed before making cultivation decisions to start the season.
Guidelines for common water source users (irrigation system) This generic guidance helps farmers to plan and implement their activities on rational way to mitigate the situation. However when following the guide lines, they need to make decisions considering the agro ecological zone, geographic location, position of their farmland in the landscape. If they are members of a common resource user group, it is necessary for them to adapt to the cultivation decisions made by the group to mitigate drought conditions.
Fact Rains not received for the last three months period or monthly rainfall is very low compared to the average monthly rainfall for the area (See chapter 2 for rainfall in your area). Reduced water flows in natural drainage lines and at water diversion points (anicut systems).
Objective To keep livelihoods intact and use some available water for production without being wasted.
Importance ď Ź ď Ź ď Ź
Assess the climatic condition and status of water resource correctly. Discuss with other members of FO/ PMC or technical personals on this aspect to get their views. Check past records and information about similar situations, gain knowledge on how they managed cultivation during such periods in the past.
Assuming that inadequate rains will occur for next cultivation season, can you cultivate the entire command area and sustain it? If your assessment on water source is good and reliable, consider others view (technical officers and farmer representatives) also when making the cultivation decision.
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Hold formal Kanna (Cultivation) meeting for the system; explain the situation and discuss how you are going to cultivate in detail
Keep all relevant officers informed and if possible, get maximum farmer participation. Decide the crop, age group, variety. (get advice of Agricultural Officers). Decide the cultivation extent based on water availability, decide whether to undertake cultivation activities in the entire command area or limit the extent of cultivation. Cultivation area can be limited by Introducing “bethma” (sharing lands located close to water source with farmers in the tail end). Tract rotation, ( cultivation of a limited area of the command in turn, one group in this season and the other in the subsequent season, one group has to fallow their lands under this situation). If Paddy is cultivated, decide the method for land preparation (LP):– Normal practice (wet and plow) Chemical application (Gramexon/ roundup etc.) and plowing Weeding/ plowing Decide the time frame, Influence farmers to do LP within a short period If OFC and vegetables are undertaken, decide land preparation method (suitable method for different crop may vary as follows: Seed drilling Raise bed/ ridge and furrow cultivation Nursery potted (OFC) seedlings – put up a nursery in small Polythine bags (7.5cm or 3”) or coconut shells filled with nursery mixture, keep two seeds in each and after 3 weeks, crop can be established in the prepared field. What is the water issuing program or schedule? Discuss this in the meeting with the help of officers; clear all the doubts at the meeting. Inform farmers to plan their own cultivation activities (planting weeding, fertilizer application, chemical application) to match with irrigation schedule discussed and not to disturb this water release plan deviating from the agreed upon plan.
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To get the highest benefit of water, pass the Kanna meeting decisions and information to all the farmers cultivating under the water source
Many lands are cultivated by share croppers on different tenure arrangements, mortgaged-in, leased-in farmers. FO has no control over these farmers and they may tend to deviate from kanna making decisions taken with FOs. Better to keep them informed and get their cooperation as well.
Proper Land Preparation (LP) suited to the crop
Based on factors such as the crops selected, geography of your land and method of your irrigation, use the appropriate land preparation method if it is a non paddy crop. Land surface must be smoothly leveled to avoid water logging and easy flow of water as uneven surfaces provide room for weed growth and difficulties for uniform distribution of water within the plot.
Paddy Cultivators Keep the bunds clean, free of rat/ crab holes. Plaster them well to avoid water leak from “liyaddha”. Maintaining strong bunds allows you to keep water for longer period in the “liyaddha” and reduce your water needs. Land preparation can do in two ways: Dry LP: - if your field is fully dry and there are green weeds, you can scrape (“Udalugame” or “Rahinawa”) surface weed layer. Then plow the land dry. Harrow it for fine soil particles. Clean bunds to plaster them later when irrigation starts. Sow dry (Kakulan) or sprouted seeds, keep some space closer to bunds without sowing.
Scraping surface layer
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Wet short LP: - if condition is similar to the one described above, clean and burn all weeds. If field is totally free of weeds, irrigate and do first plowing, then clean bunds do second plowing, puddle, plaster the bunds and sow sprouted seeds. This method requires less than 10 days for LP and saves a lot of water compared to the normal method. Some underground weed parts can sprout if they are not totally destroyed. If weeds density is high, use a total weedicide to destroy weeds.
Not to drain out/ over flowing or leaking water. Avoid water waste
Some irresponsible farmers do not pay attention to save water and they open the farm inlet and go for their other activities. As a result, water is not fairly distributed within the field. Sometimes water may overflow the bunds. Don’t do this. After you get sufficient water, close your farm inlet and allow next person to take water.
If you are a paddy farmer, don’t drain out standing water in the first week after sowing and refill (“isna badhinawa”). Instead of this get water just to saturate the soil without keeping standing water in you land.
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Plan your cultivation activities ahead or suitable time compared with your irrigation calendar. Some farmers apply chemicals (fertilizer, weedicides and pesticides) in the following day of irrigation after draining out all the water filled in the land. Don’t do this, plan your activities well considering water saving. If you are a paddy farmer, check bunds of your field regularly after sowing for cracks or holes. If any cracks or holes, are found, seal them immediately to prevent water leaking.
Some parts of your field may have access to water from nearby drainage canal. If possible, tap these sources and reduce the demand from main source of water.
Conjunctive use RF/ ground
If you are a non paddy farmer and your field is located close to irrigation canal system or close to drainage system, you can tap water which is lost when water is conveyed in the canal system by digging shallow wells. This will reduce the demand on main water source and increase system water productivity. After irrigating the field, keep all outlets (“wakkada”) close. If rain occurs in between two irrigations, it will collect some water in liyaddha and you can postpone next irrigation for a few more days.
Don’t keep outlets open like this after irrigation
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Improve organic matter content of the soil for increase water holding capacity of the soil
Adding organic matter to the soil is the best way for improving its water holding capacity. If you can, add compost fertilizer, poultry litter or cowdung to your farm for immediate results. Adding green leaves and straw needs some water to get them decompose. Further, it takes some time to decompose. This type of organic matter use is not recommended when there is a shortage of water. Contact your AI for further information and recommendations. Refer soil and water section for additional information.
Cultivate short age crop verities
Paddy cultivation in a shortest time needs water for 65-day period. Green gram needs 65 – 85 days of soil moisture for complete cultivation. Finger millets, Gingerly, Ground nut and Sweet potatoes need 75 – 110 days period and a relatively similar period is required for most vegetables for complete cultivation.
Paddy cultivation We have Paddy varities in different age groups like 2.5 month, 3 months, 3.5 months 4 and 4.5 months. Consider your water availability and LP requirement when selecting the best suitable variety. (check the seed paddy availability before selecting the variety). Try to get all the farmers under the system to grow a same variety or age group (This can be decided at the cultivation meeting). If possible to find seed paddy, grow 2.5 month paddy variety. With LP period it needs water only for 65 days. Most farmers grow 3.5 month Paddy (105 days) in normal Yala season and finally fail because of non availability of water for the last two irrigations. If they grow 2.5 – 3 month age varities these failure can be avoided. OFC and Vegetable Cultivation Non Paddy crop or OFC cultivation is the best option for water shortage dry seasons. Paddy needs at least near saturation condition of soil moisture but other crops can be managed with less water. - 121 -
Most vegetable crops have special advantages though they have not recieved due attention of most farmers and planners. Most of the vegetable crops produce yield at 60 days after planting. Radish, Okra Green chili, Capsicum, Cabbage can be harvested after 45-50 days. Most of root crops can be harvested after 60 days. You can’t do this in Paddy or field crop cultivations. If water situation becomes worse, most leafy vegetal crops like Onion, Spinach etc. can be harvested at that point and marketed.
management facts 10 Water 1. System water management
Keep canal system ready before starting irrigation. (Walk-through with officer-farmer group to identify critical points and waste locations. Take quick remedial measures to stop water waste or rectify the problem.). Prepare water issue operational plans in such a way to minimize conveyance losses as appropriate to your system. (tail end first and head last method - get advice from irrigation officials). Start rotational water issues, keep maximum irrigation intervals. Be careful not to give stress to crops at critical stages of crop growth (consult Agricofficers and irrigation officers). If the water situation seems not adequate, increase irrigation interval to maximum allowable time period according to the soil and other conditions. Educate farmers about changes.
2. Farmer level water management
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Ask farmers to implement water saving measures described in Chapter 7. Educate farmers well on rotational irrigation schedule, each farmer must know when he get his irrigation turn, (notice can be displayed at secondary canal head etc.). Minimize illegal tapings; keep main system stable to ensure delivery of correct quantity according to the schedule. Keep system clean and de-silting for easy flow of water. Don’t do illegal tapings and disturb operational schedule implemented by the system operators. Take your turn only. If you have water problems, discuss with the relevant officials. Don’t allow water to overflow or leak through bunds. Some systems have been designed to issue water to one or two allotments at a time (whole FC flow for one farmer – large volume in short period). Farmer may not be able to manage flow within his land and this may cause irregular moisturizing. Group of two or three neighbor farmers can get together and share the full flow for a longer time period in such cases. This allows you to handle manageable flow in long duration. Add organic matter to your field as much as possible. This will improve water holding capacity of the soil. If you are a non paddy farmer, use suitable mulch to cover soil surface to reduce evaporation from soil. Do weeding or apply weedicide to reduce competition for water by weeds.
Guidelines for rainfed farmers in wet zone - Landha, Ovita and Koratuwa The farmers who cultivate isolated piece of lands (referred by different local names like kotuwe, landha, ovita) individually are considered in this section. Most farmers cultivate vegetables or some non paddy crops in these lands. Some crops are not seasonal and multiple crops giving year round income too are grown in different areas of land. They start cultivation in early October with initial rains, then another crop is planted in January towards the end of Maha season. Again they start planting in early May if season seems to be good. Farmers do not normally start planting new crops under rainfed condition in February/ March period and July – September period based on their experience of non availability of water (this varies with the area and location of your field). If your climate forecasting assessment is not satisfactory there is a risk to go for new planning or crop establishment.
When you make cultivation decision always assess what will be the next four months’ climate. If it is dry, select low water required crops for cultivation (Refer Table 2). When establishing crops in the filed, locate long age crops in down slope areas of your field. Soil moisture availability is higher and retain for a longer period in down slops compared to that in up slopes. Always plant short age, drought resistant crop varities in upslope area of your field. Add organic matter, cow dung, poultry litter or compost fertilizer as much as possible to soil. This will absorb much water and retain it for longer period to meet crop water requirements. Use basin method of land preparation; construct small basins if land is slopy to retain rainwater. These basins will not allow runoff generation and all the water received will be infiltrated into soil. Cultivate crops which can be harvested before optimum harvesting period. E.g. leafy vegetable etc..
If drought conditions become visible in the middle of the season, rain-fed farmers can adopt soil moisture conservation measures described below.
Basin method of land preparation
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Fact How to manage the crop with less-rain (below average) or no-rain condition.
Objective Maintain existing crop to get maximum benefit under dry weather condition.
Importance If you feel the climatic condition is going to be dry, donâ&#x20AC;&#x2122;t disturb soil surface. If you disturb the soil surface it will increase soil evaporation and will lose considerable amount of soil moisture.
Use agricultural water saving practices to reduce water demand
Reduce water demand by removing weeds and unproductive plants
If the farmers have cultivated non paddy crops, they can use mulches to cover soil surface, adding organic matter like coir dust (Kohu-bath), sawdust and paddy husk to cover soil. This will reduce soil evaporation and improve water holding capacity.
Weeds are competing for water with cultivated plants and use considerable amount of irrigation supply. Unproductive plants also use considerable amount of water. The water consumed by weeds and unproductive plants can be saved by removing them from the field. When you remove the weeds and unproductive plants, do minimum disturbance to the soil, to reduce soil evaporation. For weed control, chemical control is the best way under these conditions. (ref. Chapter 5)
Guidelines for rainfed farmers in the dry and intermediate zone Rainfed farmers in dry and intermediate zone cultivate crops, mostly, one season per year under rainfed conditions. Normally it starts at the end of September to early November period. Dry land preparation is common in Bingiriya, Wariyapola and Southern Nikawaratiya in the Intermediate zone. If your climatic assessment for next four months is below average rainfall, you must choose short age low water required crops like Kurakkan (finger millet),Tala (Gingerly) Mung (Green gram) Cowpea for cultivation. Guiding actions are same as for rainfed farmers in the wet zone.
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Agro-well farmers (wet, dry and intermediate zones)
Solar powered water pump
All agro-well farmers have assured water source for the cultivation to some extent. Water availability and quality are also important factors for their consideration before starting cultivation. With the background knowledge about the recharging capacity of the well, you must know how much land extent you can irrigate in one pumping session. Consider following factors. Use basin method of land preparation. This would ensure that total irrigation water will be absorbed into soil when irrigated. If your neighbors also have agro-wells near by, you must be careful because the water is drawdown fast while recovery becomes slow when all farmers operate simultaneously. You may not be able to withdraw expected amount. Keep maximum irrigation interval - check soil moisture availability before irrigating. Check soil moisture below 10cm (root zone) of the soil surface. Not like at the beginning, during the, tail end of the season, water level goes down and recovery also get late. Then the irrigating extent will be shrinking. Cultivate crops which can be harvested before optimum harvesting period. E.g.: Okra, Brinjal, Leafy vegetable, Cabbage, etc. Similarly in moderately well drained soil class if other field crops or horticultural crops are grown, adequate care is needed to provide a sufficient drainage facility. Planting on raised beds, ridges or making drains in the field is important to drain out the excess water. - 125 -
CHAPTER - 5
BEST CROP MANAGEMENT PRACTICES FOR DROUGHT - 126 -
Effect of water deficit on growth and yield of rice During Cultivation Season Low land rice is extremely sensitive to water shortage and effects of drought are seen when soil water content drops below saturation. Water stress at any growth stage may reduce yield. The most common symptoms of water deficit are leaf rolling, leaf scorching, impaired tillering, stunting, delayed flowering, spikelet sterility and incomplete grain filling. Water deficit during the vegetative stage may reduce plant height, tiller number and leaf area, but yield will not be affected by the retarded growth if water is supplied in sufficient time to permit the plantâ&#x20AC;&#x2122;s recovery before flowering.
The rice plant is extremely sensitive to water stress symptoms at late booting stage, anthesis followed by grain filling stage and from Panicle initiation to late booting stage.
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Rice crop management practices to cope with drought
There is no systematic inventory, definition or quantification of water scarcity available in rice growing areas. In principle, water is scarce in the dry season when lack of rainfall makes cropping impossible without irrigation. Threefore, farmers tempt to conserve water rather than flooding their fields continuously. Depending on the source of water availability, Saturated soil culture farmers follow two different rice systems as lowland irrigated rice system, and lowland/ upland rainfed rice system. In lowland irrigated rice system fields are flooded to about 5-10cm depth. With progressive water scarcity, saturated soil culture (SSC) may be practiced under flooded ponded water level from 5-10cm to 0-1cm without yield loss. With still further increasing water scarcity, the practice of alternate wetting and drying (AWD) may be implemented without much yield loss. Finally, Aerobic rice system may be followed when the water availability in soil is just below the field capacity level. When irrigated water is not available, farmers adopt rainfed rice Alternate wetting & drying system which gives very low yield.
Even though about 75% of the total extent of rice is irrigated, scarcity of water is a common occurrence in different growth stages of its life cycle under rainfed system. Under favorable rainfed system entire crop water requirement during the season is received from rainfall. These fields are found in wet zone districts. Based on the rainfall received, the rainfed ecosystem is further classified into favorable and unfavorable rainfed systems. Moisture stress during the rice cropping period is considered as major yield limiting factor in Sri Lanka. However, with decreasing water availability, soil, water and crop management practices during the whole growing season need to be considered. Under unfavourable rainfed system, crop may suffer due to inadequate rainfall. Such fields are found in districts of wet and intermediate zone. In wet-seeding, pre-germinated seeds are broadcast into puddled and leveled fields that are free from standing water. This method of sowing involves precision leveling of the lowland rice field, preparation of seedbeds and draining of water, seed treatment and incubation, sowing of seeds, etc. Stand establishment by this method varies with the quality of land preparation, weed competition, water management, and rainfall during the initial period after sowing. Leveling of the field to drain water completely is a very important step in direct-seeded rice culture which also would ensure good field water management.
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Water management Lowland irrigated rice system includes continuous flooding, saturated soil culture (SSC), alternate wetting and drying (AWD) and aerobic rice techniques depending on the level of water availability.
a) Saturated Soil Culture (SSC) In Saturated Soil Culture (SSC), the depth of flooded water is reduced to 0-1cm.
Around 1 week before and 1 week after the peak flowering, standing water should best be kept at 5cm depth to avoid any possible water stress that could result in severe yield loss.
SSC would require frequent (once in 2 days) application of small amount of irrigation water, and hence require a high level of control over irrigation water.
b) Alternate Wetting and Drying (AWD) In alternate wetting and drying (AWD), water control is required by the farmer. With own water sources this is not a problem. In community based or large scale irrigation systems, a communal approach to AWD is required in which delivery of water to groups of farmers is scheduled to realize a certain pattern of AWD. In this system field is allowed to dry for a certain number of days before applying irrigation water. The number of days that the soil is left dry may vary from 1 day to more than 10 days. After irrigation, the field water
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When the water level is 15cm below the surface of the soil, irrigate and flood the soil to a depth of around 5cm in AWD technology. AWD may be begun from a few days after transplanting or 10cm tall crop after direct seeding until first heading.
Around 1 week before to 1 week after the peak flowering, flooded water should be kept at 5cm depth to avoid any water stress which result in some yield loss. Subsequentiy during filling and ripening, AWD.
Nitrogen fertilizer should be applied on dry soil just before irrigation preferably.
If weeds are present in the early stages of crop growth, the implementation of AWD may be postponed for 2-3 weeks until weeds are suppressed by the flooded water.
Beneficial effects on soil pH, soil organic matter buildup, phosphorous, iron and zinc availability, and biological nitrogen fixation gradually decrease when the field is shortage of water. Under alternate wetting and drying (AWD), negative effect on soil pH in some situations, decrease the availability of phosphorus, iron and zinc.
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c) Aerobic rice system
With increasing water scarcity, aerobic rice system becomes a viable alternative to AWD. Aerobic rice is a production system in which specially developed varieties are grown in well-drained, nonpuddled, and nonsaturated soils. With appropriate management, the system aims for yield of at least 4-6t/ha. The usual establishment method is dry direct seeding. Aerobic rice may be rainfed or irrigated. Irrigation can be applied through flash-flooding, in furrows or by sprinklers. Irrigation is not used to flood the field but to just bring the soil water content into the root zone up to field capacity. How much less water is used under aerobic conditions than under flooded conditions depends mostly on the seepage and percolation losses under flooded conditions and on the deep percolation losses of irrigation water under aerobic conditions. The amount of deep percolation depends on the combination of soil water holding capacity and method of irrigation. In aerobic rice system, conservation practices such as mulching and minimum tillage are encouraged. This technology is suitable in favorable uplands (where the land is flat, rainfall with or without supplementary irrigation is sufficient to reach field capacity, and no serious fertility limitations occur), in rainfed lowlands and in water scarce irrigated lowlands. Under fully aerobic conditions, micro nutrient deficiencies and some soil borne pest and diseases such as nematodes, root aphids and fungi occur while soil organic carbon content decreases. Rice cannot be grown continuously on the same place without yield decline when practicing aerobic rice system. Crop rotation is necessary under such conditions. Problems of more weed growth and many species of weeds occur in this system than in the continuous flooding system.
Guidelines for drought conditions after cultivation season start When planning a cultivation season, climatic conditions should be favorable, assessment be normal or above normal. But after making cultivation decision ie. month or two after establishing the crop, the climatic conditions may change to dry or drought condition. Then the expected tank storage may decrease. The water source will not have sufficient water to complete the cultivation season. What options can we adopt in this situation?
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a) Guidelines for commom water source users
How to manage the crop with less rain (below average) or no rain condition.
Maintain existing crop to get maximum benefit under dry weather condition.
All farmers in the system must follow instructions issued by the system operators and act accordingly.
Organize awareness meetings with farmers Keep the farmers alert about the situation changes. Review situation periodically and update farmers.
Expand irrigation intervals to suitable level Depending on the crop growth stage, change the irrigation interval for maximum allowable limit.
Use water saving practices to reduce water demand If the farmers cultivate non paddy crops, they can use mulching to cover soil surface, adding organic matter like coir dust (Kohu-bath), sawdust and paddy husk would reduce soil evaporation and improve water holding capacity.
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Reduce water demand by removing weeds and unproductive plants
Monitor canal flows to identify water wasting locations to save water
Weeds compete for water with cultivated plants and considerable amount of irrigation supply is used by weeds. Unproductive plants also use considerable amount. This water can be saved by removing these plants from the field. When you remove the weeds and unproductive plants, do minimum disturbance to the soil in order to reduce soil evaporation. For weed control, chemical control is the best way under these conditions.
Monitor canal flow at strategically important locations to equal distribution and control conveying losses. Remove obstacles to the canal flow for free and easy distribution. Appoint few observers to see how farmers behave in the field. Fines can be introduced to control misuses.
Encourage farmers use to alternative water sources and reduce pressure on main system In most of the systems, farmers who have their fields located closer to drainage lines have access to drainage water and they can reuse this water. Some farmers have dug wells in their field and when water is flowing in the main system seepage water is collected in them. This water also can be reused to reduce main system demand and save some water.
If the water availability not sufficient for entire cultivation, abandon some cultivated areas to rescue other areas Discus with all farmers the possible options for reducing the cultivated area to rescue some part. Some possible options are: All farmers abandon their cultivated area by half. Let off tail end tracts of the system to get some production from the head end tracts. (Tail end farmers can be recommended to get crop insurance coverage or head end farmers have to pay some money for providing water entitlement to tail end farmers, who allow them to use that water to save their cultivation. Some payment of compensation. If drought conditions become visible in the middle of the season, rain-fed farmers can adopt soil moisture conservation measures described bellow.
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b) Guidelines for Rain-fed farmers
How to manage the crop with less rain (below average) or no rain condition.
Maintain existing crop to get maximum benefit under dry weather condition.
If the climatic condition is expected to be dry, donâ&#x20AC;&#x2122;t disturb soil surface, Disturbance of the soil surface will increase soil evaporation and will lose considerable amount of soil moisture.
Use agronomic water saving practices to reduce water demand If the farmers cultivate non paddy crops, they can use mulching to cover soil surface, Adding organic matter like coir dust (Kohu-bath), sawdust and paddy husk would reduce soil evaporation and improve water holding capacity.
Reduce water demand by removing weeds and unproductive plants Weeds are competing for water with cultivated plants and use considerable amount of irrigation supply by weeds. Unproductive plants also use considerable amount, these water can save by removing these plants from the field. When you remove the weeds and unproductive plants, do minimum disturbance to the soil, to reduce soil evaporation. For weed control chemical control is the best way under these conditions.
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c) Guidelines for Agro-well farmers (all climatic zones)
How to manage the existing crop in drought conditions.
Maintain existing crop to get maximum benefit under dry weather condition.
Based on your knowledge of the field and crops cultivated, irrigate the blocks which need water more frequently. Depending on your field landscape; cultivation blocks on upper slope may need more water than cultivation blocks in down slope.
Dropped water level in the well take longer time to recharge It takes longer duration to recharge the well. Amount of extractable water would reduce. Distribute water quickly all over the block. It is not necessary for the soil moisture condition to reach the field capacity.
Expand irrigation intervals to suitable level Depending on the crop growth stage, change the irrigation interval for maximum allowable limit.
Use agronomic water saving practices to reduce water demand If the farmers cultivate non paddy crops, they can use mulching to cover soil surface, Adding organic matter like coir dust (Kohu-bath), sawdust and paddy husk to cover soil will give two effects; reduces soil evaporation and improves water holding. - 135 -
Reduce water demand by removing weeds and unproductive plants Weeds are competing for water with cultivated plants and use considerable amount of irrigated water. Unproductive plants also use considerable amount of water. This water can be saved by removing these plants from the field. When you remove the weeds and unproductive plants, do minimum disturbance to the soil, to reduce soil evaporation. For weed control chemical control is the best way under these conditions.
Pest management strategies under drought Infestation by pest and diseases, continue to be major constraints to food and agricultural production. Crop losses significantly reduce the amount of food available for human and animal consumption, contributing to food insecurity and poverty. The control of plant pests still entails substantial use of pesticides, which affect human health and the environment. Climate is thought to drive the incidence of pest and diseases. Among the climatic factors, precipitation and temperature are two important factors that determine abundance of pest and diseases. For instance, increasing temperatures leads to dvelop more insect generations in a year. Precipitation can influence the onset of plant diseases. It is often difficult to separate the influence of increased temperatures from that of drought stress on host plant as both are likely to increase the amount of readily available and assimilable nitrogen in plant tissues, making them more susceptible to phytophagous insects.
Causal organism and symptoms Plant ill-health is caused by biotic or abiotic factors. Among the abiotic factors are unfavourable water relationships (excess or lack of moisture), extreme temperature (low or high), nutrient toxicities or deficiencies in the soil, adverse soil physical properties such as insufficient soil, air and excessive soil compaction. The principle biotic factors responsible for plant diseases are insects, mites, fungi, bacteria, viruses, viroids, mycoplsma and nematodes. The insects have three body parts; head, thorax and abdomen and 3 pairs of legs. Insects begin its life cycle as an egg and changes its shape as it grow. This is called metamorphosis. In insects like butterfly, moth, and beetle, the egg hatches into a larva which transforms in to a pupa and eventuaiiy develops in to an adult.
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Leaf minor damage
In other insects like the grass hoppers and aphids the young insect (nymph) looks like the parent and sheds its exoskeleton several times when it grows Insect pests can also be identified from the nature of the damage they do. The presence of serpentine leaf mines are an indication of leaf minor damage. Irregular leaf holes in leaf lamina are most often caused by leafâ&#x20AC;&#x201C;eating caterpillars. Presence of nymphal, larval and pupal skins is further indication of insect infestation. Additionally, species of sucking insects produce large quantities of honeydew which is a good medium for growth of sooty moulds.
Damage caused by
Mites are eight-legged arthropods who live in colonies, mostly on the lower surface of leaves. Adult females deposit small, eggs on a leaf and immature mites resemble adults, except they have only six legs during the first instar stage. Mites feed on the foliage by sucking the sap which results the leaves to turn yellow or bronze in color and drop off. In some mite species, infested leaves and branches can be enclosed in fine silken webbing. Nematodes are tiny, round-bodied, unsegmented, worms. Plant-parasitic nematodes pierce plant cell walls with their stylet, and ingest the plant cell sap into their digestive system. Approximately 10% of all nematodes feed on plants, living around or in the roots. The most well known is the root knot nematode (Meloidogyne spp.), because of the distinctive galls it causes on infected roots, itâ&#x20AC;&#x2122;s wide distribution, and the wide host range (including most common vegetables, ornamentals, and fruit trees.). Symptoms of nematode infestation include wilting during the warmest period of the day, chlorosis, stunted growth, and general lack of vigor. - 137 -
Toxicity for applicants
Toxicity for non target organism
Development of resistence for pests
Principles and components of pest management Disadvantaged of Chemicals The reliance of chemicals for pest control has lead to many adverse effects such as toxicity to consumers, applicators and other non-target organism, development of resistance of pests to insecticides and persistence of chemical in the environment and biomagnification through the food chain. To minimize such problems, farmers must diversify their pest control practices. This strategy is what scientists now term Integrated Pest Management (IPM). IPM programs use current, comprehensive information on the life cycles of pests and their interaction with the environment. This information, in combination with available pest control methods, is used to manage pest damage by the most economical means, and with the least possible hazard to people, property, and the environment. IPM emphasizes biological control, plant resistance, planting practices (cultural control), and other non-chemical methods. Pesticides are used only when cost/benefit analyses show that their use is truly justified and that acceptable alternatives do not exist: their use is supplementary, rather than routine. In this way, IPM prevents pests from rapidly developing resistance to pesticides and lengthens the pesticidesâ&#x20AC;&#x2122; period of value for pest management. Following are the components of IPM. Biological control: All insect pests and weeds are affected by natural enemy species (predators, parasitoids, or disease agents) that limit the pestsâ&#x20AC;&#x2122; reproduction, growth and population. Biological control uses natural enemies to keep pest populations at an acceptable levels. Natural enemies are of three main types: parasitoids low predators and pathogens.Examples of predators are spiders, ladybirds, lacewings and predatory mites. Parasitoids are specialized insects that lay their eggs in, on, or close by individuals of another species. The emerging larvae generally live on the blood and tissue of the host. The adults are not parasitic, but they fly about looking for a new host for their offspring. Examples of parasitoids are Encarsia formosa and Trichogramma spp., which are applied commercially in greenhouses. Microbial pest control agents are microorganisms like Bacillus thrungiensis applied to the crop for ingestion by insect pests, or directly onto the insect pests, fungi or weeds to destroy them. The effectiveness of natural enemies is enhanced by conserving native parasitoids and predators. Conservation can be accomplished by reducing the harmful effects of pesticides on the beneficial species to favour the growth of predators and parasitoids.
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Cultural control: Cultural control is an agronomic practice used consciously or unconsciously by farmers to improve yields. Its effectiveness on pests is difficult to assess. A specific method may decrease the population of one pest but increase that of another. Some practices may effectively control pests but, at the same time, reduce crop yields. The following are cultural practices that also achieve crop protection:
Using pest-free propagation materials. Infested or infected seeds and plant materials, such as tubers, rootstocks, cuttings and grafts, can infect an entire crop.
Ploughing the fields and burning stubble. This method produces good seedbeds or plant nursery because it destroys insects, diseases, and prevents the growth of weeds and ratoons that are likely to harbour viruses. Turning the soil exposes insects that pupate in the ground.
Synchronous planting of crop fields. This practice is said to prevent continuous growth of pest populations over long periods of cropping. However, this is not true of all pests. For example, stem borer incidence is usually lower with asynchronous rice planting.
Planting susceptible trap crops. Trap crops are crops planted before or between rows of a cultivated crop to divert pests from the main crop. When planted between cropping seasons, trap plants can also be used to maintain natural enemies.
Intercropping. The planting of different crops or varieties within the same area diversifies the available habitat and may inhibit the expansion of pests. The microclimate prevailing in a mixed crop is different from that in separately cultivated crops. The effects on a pest can be positive or negative, depending not only on the pest, but also on the reactions of possible natural enemies. - 139 -
Rotation with cucurbitacea solanacea
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Crop rotation. Varying the annual crop in the same field from year to year interrupts the specific relationship between pests and host plants and can prevent the growth and expansion of pests and pathogens, particularly those living in the soil. Example of crop rotation is growing rice for one seasons and planting potatoes in the next season as adopted by the farmers in Welimada area. Crop rotation can be an effective measure against soilborne pathogens, nematodes and soil insects, if the rotation cycle is sufficiently long. As different crops usually require different soil cultivation practices (such as shallow or deep ploughing, harrowing, ridging and broadcast sowing), crop rotation also plays an important role in controlling weeds.
Fertilizer application. Well-balanced fertilizer application results in healthy plants. Organic fertilizer, which improves the physical and microbial properties of soils, is better than inorganic fertilizers.
Sanitation. Sanitation in storage areas, farmyards and fields is a means of preventing pests and diseases by eliminating breeding sites. For example, cutting down dead tree trunks of coconut will remove the breeding site of the rhinoceros beetle, Oryctes rhinoceros.
Host-plant resistance. Host-plant resistance is the inherited ability of a plant species to ward off or resist attack by pests or to be able to tolerate damage caused by pests. Resistant varieties are one of the important components of pest management and can easily be combined with other control methods. In the field, however, crop resistance to insect pests and diseases can eventually break down. Therefore, plant resistance breeding programmes continuously select new varieties to replace older ones.
Physical control. Pests are physically collected and then destroyed in areas where labour is cheap. The use of mechanical implements for weeding is becoming popular. Fences or screens protect highvalue crops from insect pests. Fences control rats in rice fields. Some physical methods for destroying pests are temperature (heating or cooling), humidity, energy and sound. Unfortunately, this type of control may needs costly equipments usually beyond the reach of small-scale farmers in developing countries.
Light sources are used to attract insects. The attracted insects are killed using other methods. When light traps are placed near water sources the attracted insects are killed by falling into water.
Factors to be considered when using pesticides Selection of a pesticide ď Ź ď Ź
Select a pesticide that is effective for the target insect with little effect on parasites and predators. Select a formulation that is effective on the pest and suitable for the condition at the time of application. For instance systemic insecticide is most effective for a sap feeding insect while contact pesticide is suitable for leaf eating caterpillars. When more than one pesticide in available, rotate their use, to reduce the development of resistance.
Application of correct amount
Read the insecticide label to choose the correct dosage of pesticide to be used. Do not increase the amount used if desired results are not obtained. There may be several factors responsible for the less effectiveness of the pesticide. Using against the wrong pest, not targeting the most sensitive stage of the life cycle of the pest, drifting by the wind, washing away by the rain and volatilization after exposing to intense sunlight are some of the causes for the infectiveness of the pesticide. Additionally, desired results may not be obtained if the pest develop resistance against the insecticide. Hence it is necessary to investigate the causal factors before increasing the dosages.
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Apply to the correct target
Choosing the correct target insect and correct placement are pre-request for effective use of the pesticide. Also, it is necessary to choose the most vulnerable stage of the pest. For instance,for mites control apply sulphur at the lower leaf surface. Initial larval stages of cabbage leaf eating caterpillars are more vulnerable for insecticide.
Apply at the correct time
Apply pesticide only if dry weather prevail 3-4 hours after application. Do not apply if high wind prevail. Application when there is lot of dew can dilute the pesticide. Apply pesticide in the evening for nocturnal pests like pod borers.
Safety measures during application
Do not apply during high winds. When spraying during low winds, avoid contamination with pesticides by walking away from the direction of wind. Do not eat, drink, smoke or blow clogged nozzle by your mouth while applying pesticide. Immediately change clothing if get wet from pesticide during spraying.
Factors to be considered after application of pesticide
Make sure the sprayer is empty. If necessary spray the remaining material on to a field. Clean the sprayer and store the spraying equipment in a safe place. Wash the gloves in a running tap before they are removed and wash them again. Bathe and wear fresh clothing. Do not enter treated fields for few days. Store the remaining pesticide in a safe place and dispose the empty containers properly.
Pest Management of Rice Environmental conditions particularly droughts and floods affect the abundance and incidence of rice pests. Late planted crops due to nonavailability of water at proper time are more prone to attack by pests like thrips and stem borers. Thrip damage is severe under water stress condition. Floods results in standing water in the fields and this favours the development of pests like Whorl maggot. Continuous submerged conditions in the field favour rice brown planthopper. Army worm and cut worm damage is severe in periods of drought followed by heavy rains. Gall-midge incidence is high in cloudy or rainy weather. High humidity and shady conditions favours development of rice leaf folders. Rice bugs prefer warm weather, overcast skies, and frequent drizzles.
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Mole cricket (Gryllotalpa Orientalis) Nature of damage
Infest upland un-flooded rice. Insects attack seeds and seedlings. Insect are easily identifiable by its large size, enlarged front legs and prothorax. Mole cricket is an important insect when flooded rice is drained or when water level varies exposing the soil.
Maintain standing water in the field. Application poisoned bait made from rice bran with an insecticide like fenthion 500g/lEC.
(Stenchaeto thrips biformis)
Nature of damage
A pest of young rice seedlings. Adult and larvae suck the cell sap from the leaf tissues. Damaged leaves roll inwards along the margins and feeding causes leaf drying resulting poor crop growth.
Submerge infested crops intermittently for 1-2 days. Use recommended insecticide like Imidacloprid 200g/l SL, Imidacloprid 70% WG, Imidacloprid 200g/l OD, Thiacloprid 240g/l SC, Fipronil 50g/l SC, Carbosulfan 200g/l SC, Dimethoate 400g/l EC, Fenthion 500g/l EC, Diazinon 500g/l EW/EC, Carbaryl 85% WP, Carbaryl 480g/l SC, Quinalphos 250g/l EC or Ethiprole 100g/l SC. In endemic areas and late planted crops, treat seed paddy with Thiamethoxam 70% WS or Imidacloprid 70% WS.
Nature of damage
The larvae feed by scraping patches of green tissue. These patches have ladder like appearance Later the leaves are cut at right angles and use it to construct cases used by the larvae for floating.
Draining the fields for several days as standing water favours pest development. However, this can aggravate weeds. Use recommended insecticides like chlorpyrifos 200g/l or chlorpyrifos 400g/l EC or Fenthion 500g/l EC.
4 Army worms and Cut worms (Melantis spp Spodoptera spp, Mythimna separate)
Nature of damage
Mostly abundant in rainy weather. Larvae feed on leaves removing large areas of the blade. Larvae may cut off the seedlings and rice panicles.
Control weeds in and around the fields Predators and parasite play key role in keeping the population low. Use the same insecticides recommended for case worm. - 143 -
5 Rice stemborer (Scirpophaga incertalis) Nature of damage
When the damage occurs to young plants, central leaves of the damaged tillers turn brown. This damage is called the dead hearts. If the damage occurs after spikelet formation no grain filling occurs and the damage is called white heads.
Use early maturing varieties. Plant the fields early. Plow the stubble immediately after harvest. Use recommended insecticide (Fipronil 0.3% GR, Carbofuran 3% GR, Carbosulfan 200g/l SC Diazinon 5% GR, Chlorpyriphos 400g/l EC, Chlorpyriphos 200g/l EC, Phenthoate 500g/l EC Quinalphos 250g/l EC) Apply insecticide only when damage exceed 10% dead hearts or 5% white heads.
6 Rice bug (Leptocorisa oratorius) Nature of damage
Both adult and nymphs feed on rice grains at milk stage, soft and hard dough stages. Feeding causes empty or small grains during the milking stage and deformed or spotty grains at the soft or hard dough stage.
Removal of grassy weeds in the fields. Avoid staggered planting in an area Use recommended insecticide (Thiocyclam (hydrogen oxalate) 50% SP, Carbosulfan 200g/l SC, Phenthoate 5% DP, Quinalphos 250g/l EC, Diazinon 500g/l EC/EW, Fenthion 500g/l EC or Phenthoate 500g/l EC). Apply dust early in the morning. Do not spray or dust after the flower opening. Apply pesticide when the bug density is 1 per 10 hill.
(Rattus spp Bandicoota Spp)
Nature of damage
Rats may eat germinating seeds or it can pull up transplanted seedlings which result in missing hills. Rats also cut and bend older tillers to reach developing panicles. Retillering of cut stems produce younger stage crop area that is surrounded by more mature rice. Hence the damage is visible from a distance.
Cut down weeds on dykes or surrounding areas to reduce shelter. Plant fields in the same area at the same time. Remove or destroy old straw piles. Use rodenticides in combination with the above cultural methods. Start baiting with rodenticides (Difenacoum 0.005% Coumatetralyl 0.0375% or Brodifacoum 0.005%, Difethialone 0.0025% RB, Flocoumafen 0.005% RB) after transplanting until grain maturity. Start pre-baiting 7-10 days prior to actual baiting. Follow the instruction given in label when rodenticides are used. - 144 -
Pest management of subsidiary food crops Pulses
Bean fly damage expression is more severe in plants under poor growing conditions affected by water stress. White fly population may increase in water stress plants with too much of leaf nitrogen. In most cases thrips are not a problem in the rainy season because the rain washes the tiny insects from the plant. In onion when the plant is under water stress the thrips damage may be magnified because the plant is losing large amounts of water from the damaged tissue. In the months of June and July thrips populations in chili are at their maximum as thrips has a rapid life cycle, and can develop from egg to adult in slightly less than two weeks under optimal weather conditions. Mite populations increases under water stress and application of mulch and incorporation of organic matter into the soil can improve the water holding capacity and reduce evaporation, thus avoid water stress.
Nature of Damage
Adult fly deposit eggs on the leaf and emerging larvae enter the veins and travel towards the base of the plants while consuming the internal tissues. As a result the base of the plants are swollen and when split open pupal cases can be seen.
Plant early with the onset of rains. Destroy the stubble and host plants. Earthing up soil around the base of the plant facilitates adventitious root formation and recovery. Apply recommended insecticides (Oxydemeton methyl 250g/l EC, Formothion 330g/l EC, Diazinon 500g/l EC, Carbosulfan 200g/l SC and Thiamethoxam 70% WS. Treat seed with Thiamethoxam 70% WS if planting get delayed. When liquid formulation are used spray at 2 leaf stage and repeat after 2 weeks if necessary.
Pod borers (Heliothis spp) Blue butterfly (Lampides boeticus) Cow pea podborer (Maruca testulalis) Nature of Damage
Flowers may be damaged and discolored. There is flower bud shedding and reduced pod production. Pods have small darkened entry holes on the surface and borers inside. Leaves and pods are stuck together by webbing and show signs of surface feeding.
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For all the pod borers following management methods are effective. Destroy of damaged pods and other plant parts. Use recommended insecticides (Chlorfluazuron 50g/l EC, Thiodicarb 375g/l SC, Novaluron 100g/l EC, Etofenprox 100g/l EC, Chlorpyriphos 200g/l EC and 400g/l EC). Spray at flowering and repeat at 2 week interval if necessary.
Pod sucking bug Nature of damage
The adult is dark brown to black. It deposit eggs in batches on the leaves or pods. Nymphs and adult suck the sap from developing pods which result shriveling of pods.
Use recommended insecticide like Carbaryl 85% WP or Carbaryl 480g/l SC.
Pod sucking bug Nature of damage
The adult insect is light brown in colour and has a white or yellow border along the two side of the body. The adult and the nymphs suck the sap from developing seeds through the pod cover.
The same insecticides recommended for other pod sucking bugs can be used.
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Pod sucking bug Nature of damage
The green colour adult insect deposit eggs in batches on the under side of the leaf. The nymphs and adults suck the sap from the developing pod.
Destroy the damaged pods and stubble after harvest. Use same insecticide recommended for pod sucking insects.
Aphids, White fly and Leaf hoppers: See the details given under common pests. Maize
Nature of damage
Larvae consume the leaf blade resulting shot holes and later bore in to the stem and damage the apical leaf resulting the death of the apical bud.
Destroy the stubble after harvest. Use recommended chemicals like Diazinon 5% GR, Novaluron 100 g/l EC, Thiodicarb 375g/l SC and Etofenprox 100g/l EC. Place the granules at the central whorl and direct spray to central whorl. Apply at 25-35 and at 45-55 days after planting.
2 Cob or grain borer (Heliothis armigera) Nature of damage
The mature larvae usually display striped patterns along their bodies and may vary in colour from light green to brown to black. Eggs are laid on the silks, larvae invade the cobs and developing grain is consumed. Secondary bacterial infections are common.
Cultivate the field after harvest to destroy pupation chambers. to reduce the population of the next generation of Heliothis. Use recommended insecticide like Thiodicarb 375g/l SC, Etofenprox 100g/l EC, Novaluron 100g/l EC and Methomyl 40% SP. Spray at tusseling in the evening. Use the instruction of the label when insecticide are used.
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Pigeon pod borer
Lampides boeticus, Heliothis armigera) Nature of damage
The damage is similar to description given for pulses.
Use resistant varieties when available. Use insecticides recommended for pulse pod borer. Start spraying at flowering repeat at 2 week interval. Three spraying are recommended. Use the instruction of the label when insecticide are used.
Nature of damage
The small black coloured fly deposit eggs after penetrating the pod cover. The emerging larvae feed on the developing seeds. Pupation takes place inside the pod and damage is not visible until the mature larvae cut open a window in the pod for pupation.
Avoid staggered cultivation. The same insecticide used for the pod borers are effective on the pod fly.
1 Chili leaf complex 2 Thrips (Scirtothrips dorsalis), 3 Aphids (Aphis gossypii), 4 White fly (Bemesia tabaci), 5 Mites (Hemitarsonemus latus) Nature of damage
Puckering and distortion of the leaves and stunting of the plants. Aphids and white fly excrete honey dew where sooty moulds can grow resulting black patches on the leaves. In the case of mite attack in addition to leaf symptoms, young foliage sometimes becomes rust colored. Incidence high in hot dry climate.
Commence cultivating early to avoid the dry hot climate that prevail in June and July. Chili crop grown in the Maha season is comparative less infested with pests. Following insecticide recommended for the management of chili leaf curl complex. Thiocyclam (hydrogen oxalate) 50% SP, Fipronil 50g/l SC, Imidacloprid 200g/l SL, Lufenuron 50g/l EC, Carbosulfan 200g/l SC, Prothiophos 500g/l EC, Phosalone 350g/l EC, Thiamethoxam 25% WG, Abamectin 18g/l EC Fenobucarb 500g/l EC, Acephate 75% SP and Profenophos 500g/l EC. When mites are present add 15g of sulphur into 10L of insecticide mixture and sprayed to the underside of the foliage. - 148 -
Chili pod borer (Heliothis armigera) Nature of damage
Adult insect deposit eggs individually on the leaves, flowers and pods. The emerging larva scrape the leaf tissues while mature larvae feed on flowers and pods making characteristics holes.
Use recommended insecticides (Chlorfluzuron 50g/l EC, Thiodicarb 75% WP or 375g/l SC, Methomyl 180g/l SL or 40% SP. Start spaying at flowering and repeat at 10 day interval if necessary. Application of insecticide in the evening is more effective.
(Spodoptera exigua and S. litura)
Nature of damage
The brown colured moth deposit eggs on leaves and emerging larvae move inside the tubular leaf and feed by scraping the leaf tissues. This results in whitish areas on the epidermis which later turn brown and dry off.
Destruction of stubble and maintaining a weed free field may result a some degree of control. Regular examination of the crop and removal of egg masses and caterpillars. Use recommended insecticide like Emamectin benzoate 5% SG, Metaflumizone 240g/l EC, Diazinon 500g/l EC/EW, Chlorfluazuron 50g/l EC, Deltamethrin 25g/l EC, Beta-Cyfluthrin 25g/l EC, Permethrin 250 g/l EC, Esfenvalerate 75g/l EC, Fenvalerate 200g/l EC and Carbofuran 3% GR Use the instruction of the label when insecticide are used In endemic areas incorporate cabofuran to soil during 1st week of planting. Other insecticide should be sprayed at first sign of infestation.
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Nature of damage
The larvae and the adult thrips scrape the leaf tissue and suck the sap. This result in air filled spaces and impart silvery sheen on the leaves. Drier the weather the quicker the onset of damage.
Plant at correct time so that harvesting is completed before the onset of dry weather where the damage is high. Plant a trap crop of maize 2 weeks before planting onion to prevent migration of thrips on to the onions. Use recommended insecticide like Imidacloprid 200g/l SL, Thiacloprid 240g/l SC, Fipronil 50g/l SC, Prothiophos 500g/l EC, Fenthion 500g/l EC, Carbaryl 85% WP, and Carbaryl 480g/l SC.
Diamond back moth (DBM) (Plutella xylostella) Nature of damage
The adult moth deposit eggs in small batches on the underside of the leaves. The emerging green coloured larvae feed on the lower epidermis leaving small holes in the leaves concentrated between the veins.
Refer to cabbage caterpillars for their management.
Plant sucking bug Nature of damage
Both adults and nymphs feed by sucking on the foliage of the crop. Starting on the edges of the leaves, white patches become visible, eventually the leaves wilt and dry. Young plants/ seedlings often die completely.
Frequent light cultivation (once or twice a week) will destroy the eggs. The residues of all Crucifers (including weeds) should be destroyed to reduce the carry-over between crops and seasons. Dimethoate 400 EC is recommended chemical. Spray when substantial number of bugs are present. Dimethoate is incompatible with sulphur based compounds.
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Leaf eating beetle (Phyllotrta spp) Nature of damage
Adult flea beetles chew small holes or pits, usually less than 3mm in diameter, in the epidermis of cotyledons, leaves, apical bud tissue, petioles, stems, heads, and pods of host plants. Feeding infrequently perforates leaves, but the tissue below the feeding point becomes necrotic, giving the leaves a characteristic â&#x20AC;&#x2DC;shot holeâ&#x20AC;&#x2122; appearance.
Recommended chemicals are Carbaryl 85 WP, Endosulfan 350 EC or Carbaryl 480 EC. Spray when the damage is observed. Direct spray to soil and roots.
Red hairy caterpillar (Amsacta albistriga) Nature of damage
Reddish brown caterpillar with orange hairs and black inte-segment areas. Eggs are laid on the under surface. The emerging larvae feed on the leaves.
Use recommended chemical such as Carbosulphan 2% DP. Apply when the damage is observed using a mechanical duster or a duster improvised using a cloth.
Leaf webber (Antigastra catalaunalis) Nature of damage
The larvae feed externally by making a loose web, which sticks several leaves together. Excreta (frass) remains between the leaves and the loose web. At a later stage, the larvae infest the sesame fruit capsule making an entrance hole on the lateral side and feeding on the seeds inside the capsule; they leave excreta on the seeds.
Use Neem seed water extract, or recommended insecticides Chlorfluazuron 50g/l EC, Tebufenozide 200g/l SC and Acephate 75% SP Use the instruction of the label when insecticides are used.
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Pest management of fruit crops Population growth of insects damaging fruit crops is affected by weather parameters such as rainfall and temperature. The growth of fruit fly population tend to increase during moderate soil moisture conditions and it is low both at high rainfall periods and drier part of the year. Although mango hopperâ&#x20AC;&#x2122;s initiation and buildup are closely associated with the reproductive stages of mango, high temperature increases the incidence while high rainfall has a washing out effect although the temperatures are optimum. Warm weather favours the build-up of mealy bugs and results higher incidence of the wilt in pineapple.
Nature of damage
The adult lay eggs on the rhizome and the emerging larvae and the adult weevil feed and tunnel in the corm of banana plant. The interference to the sap flow results withering and premature death of the leaves. The plants may have small bunches with under size fruits.
Destroy harvested pseudo stem by cutting them and allowing then to dry. Maintain a crop free period before replanting banana in infested fields. Use healthy planting material. Treat planting material by soaking in a mixture prepared by mixing ash, cowdung, an insecticide and water. For chemical control, prepare traps by cutting 6-10cm disc from harvested banana plants. Sandwich 6g carbofuran between 2 discs and place them in the fields. Use about 25 traps for an acre and replace the trap once a month.
Stem weevil (Odoiporus longicolis) Nature of damage
Female weevil lays eggs on the leaf sheath. The emerging larva tunnel the pseudo-stem and feed inside these tunnels which lead to break away of pseudo-stem due to wind.
Methods used for the management of corm weevil is effective.
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Mealy bug (Dysmicoccus brevipes) Nature of damage
The mealy bugs live in colonies on the base of the plants or on the stalk of the fruits. It vectors pineapple wilt disease resulting reddening of the leaves and upward rolling of leaves under severe infestation. Ants protect mealy bug colonies and help in their dispersal.
Treat planting materials by dipping in a insecticide solution (Acetamiprid 20% SP Profenophos 500g/l EC, Prothiophos 500g/l EC or Carbosulfan 200 g/l SC) for 5 min. and allowing it dry for one day before planting. To prevent crown rot mix fungicide containing Metalaxyl 8%, and Mancozeb 64%. Control of caretaking ants can reduce the incidence as they protect the mealy bugs from parasites and predators. Previously infested fields should be turned over and all crop residues removed and burned as crop residues and grass roots left in the field may harbor mealy bug populations. If there is infestation in an established plantation use any one of the insecticide used for treating planting materials. Apply insecticide to wet the base of the plant.
Leaf piercing caterpillar (Duedoris isocrates) Nature of damage
The blue coloured adult butterfly lays eggs on the leaves, flowers or on small fruits. The emerging larvae pierce the fruits and feeds on the succulent parts and seeds. Secondary bacterial and fungal infestation usually sets in after the insect attack.
Cover the fruits using paper or cloth bags at early stages.
Citrus butterfly (Papilio spp) Nature of damage
The caterpillars feed on the young as well as mature leaves. The damage is severe in nurseries and young plantations.
Hand picking of the caterpillars is the most suitable method of control in small orchards and home gardens. Use an insecticides when the infestation is high.
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Citrus leaf miner (Phyllocnistis cittrella) Nature of damage
The larvae mine inside the lower or upper surface of newly emerging leaves, causing them to curl and look distorted with silvery irregular mines.
Management measures should be adopted in nurseries and new plantations. Spray recommende insecticides (Phenthoate 500g/l EC) on to young foliage after the removal of infested leaves.
Fruit piercing moth (Eudicima fullonia) Nature of damage
The adult use armoured proboscis to penetrates the skin or rind of fruit to feed on the juice. The tissue around the holes made by piercing are off coloured and start rotting.
Cover the fruits about a month before fruit maturity. Collect and destroy fallen fruits. Use a bait made by mixing 500g of sugar or mollases with 10L of water. Add small amount of toddy, few fruit pieces and an insecticides. Fill small containers( about 1/4th) with this solution and hung them in the field.
Papaya scale insect (Aspidiotus destructor) Nature of damage
Round brown coloured scale insects colonies may be found on fruits. Sucking of sap results yellow patches on the fruits.
Economic damage occurs very rarely. Coccinelid beetles keep the population below economic thresh hold.
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Papaya mealy bug Nature of damage
Clusters of cotton-like masses on the above-ground portion of plants. Chlorosis, plant stunting, leaf deformation, early leaf and fruit drop, may result due to injection of toxic saliva during feeding. Sooty moulds develop due to production of honey dew. Heavy infestations are capable of rendering fruit inedible due to the buildup of thick white wax.
Biological control using parasite Acerophagus sp. was found to be very effective. Washing away the infested mealy bug using a stream of water is effective under moderate infestation. Use of soap kerosene and water solution is also found to be effective. For chemical control use Thiamethoxam 25% WG, Imidacloprid 200g/l SL or Mineral Oil.
Mango fruit fly (Bactrocera spp) Nature of damage
The adult is brown coloured fly with yellow spots on the abdomen. Injury to fruit, occurs through oviposition punctures and subsequent larval development. Deformation of fruits, dropping of immature fruits and rotting of fruits results due to larval feeding.
Collect and destroy the fallen fruits under the trees to destroy the developing larvae. Use Methyl eugenol traps through out the year (8-10 traps/AC) to attract the male insects and to reduce their population. Use polythene or paper bags to cover the immature fruits. Use recommended insecticide (Fenthion 500 EC) and spray it to wet the foliage and immature fruits. Mix 25g of sugar per litre of insecticide solution. Protein bait is effective to attract sexually immature female fly. The protein bait mixed with an insecticide (Spinosad) spot sprayed on the underside of leaves on the lower branches at 2 weekly interval.
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Mango leaf hoppers (Amritodus brevistylis, Idioscopus clypealis, I. niveosparus)
Nature of damage
Sucking of sap by the nymphs and adults results in drying and fall of inflorescence and young leaves and presence of sooty moulds is an indication of the presence of hoppers.
Orchards may be kept clean by ploughing and removal of weeds Removal of over crowded, criss â&#x20AC;&#x201C; cross, overlapping, infested branches to discourage the micro environment for hopper multiplication. Use recommended insecticides (Imidacloprid 200g/l SL, Dimethoate 400g/l EC or Thiamethoxam 25% WG). Prior to new flush growth spray to colonized areas on the trunk and foliage as spot applications. If necessary, apply at flower initiation and new flush growth. Dimethoate is incompatible with sulphurbased compounds.
Mango seed weevil (Sternochetus mangifera) Nature of damage
It is impractical to distinguish between infested and uninfested seeds unless they are cut open. Dark coloured excreta is found near the seed coat in the pulp in infested fruits.
Removal of fallen fruits and if the infestation high use a recommended insecticide (Dimethoate 400 EC) at flowering. A strict policy of not bringing mango fruit onto the orchard will greatly reduce the chance of infestation.
Stem borer (Batocera rufomaculata) Nature of damage
The grub of this pest feeds inside the stem, making tunnel upward which results in drying of branches and in severe cases death of tree. Frass ejected from the larval borings may collect in bark crevices around and below the oviposition site or accumulate at the base of the tree.
Removal and burning of infested branches. Collection and destroying the adult insects. At the early infestation stage, removal of the larvae by boring in to entrance holes. Prune the dying branches and apply insecticide like pyrethroid. Since the insect attack weaken trees, maintain the vigour of the tree by proper tree management such as fertilization, irrigation, weeding and pruning.
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Pest management of vegetable crops Most of the vegetable crops are cultivated under rainfed conditions. Hence there is a high probability of the crop to be affected by drought stress. Damage by pests like thrips, white fly and mite may be aggravated under drought conditions. The growth of fruit fly population tend to increase during moderate soil moisture conditions and it is low both at high rainfall periods and drier part of the year.
Fruit fly (Bactocera cucurbitae) Nature of damage
The adult is a yellowish brown fly with stripes on the wings. Injury to fruit occurs through oviposition punctures and subsequent larval development. Deformation of fruits, dropping of immature fruits and rotting of fruits results due to larval feeding inside the fruits.
Cover the fruits at early stages using polythene bags. Collection of infested fruit and bury them 3 feet under soil surface. Cultivate the soil around the plants using a rake to expose and destroy the pupa. Early harvest of mature green fruits. Disposal of crop residues immediately after harvest. Addition of lime is helpful to kill emerging larvae. Use of a protein bait to attract sexually immature female fly. The protein bait mixed with an insecticide can be sprayed on to the plants as a spot application. Use recommended insecticide (Fenthion 500 Ec) and spray it to wet the foliage and immature fruits. Mix 25g of sugar per litre of spray when insecticide are used.
Gallfly (Lasioptera falcate) Nature of damage
Swelling of vines caused by the larvae of the gall fly feeding within the stem. The galled vines become stunted.
Splitting the stem and removing the maggots. Recommended insecticides are Carbaryl 85% WP, Carbaryl 480g/l SC or Profenophos 500g/l EC.
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Aulacophora (Aulacophora spp) Nature of damage
The adult is a beetle with various colour forms such as orange, brown, blue, ash and black. The larval and adult feeding result in irregular holes on the leaves. The larvae may damage the root system of plants.
Use recommended insecticide; Carbaryl 85% WP, Carbaryl 480g/l SC or Carbofuran 3% G. To control the larvae apply carbofuran about 2cm under the soil. Apply other insecticides on to the foliage to control the adults.
Paddle legged bug (Leptoglossus australis) Nature of damage
The hind legs of the insect is flattened similar to a paddle. Both adult and nymphs suck the sap from fruits resulting blackish areas. Feeding on the vines may dry up the vines.
Collection of the adults early in the morning or in the evening in to container with kerosene. Application of recommended insecticide Carbaryl 85% WP or Carbaryl 480g/l SP. Apply insecticides when nymphs are observed in colonies in the morning.
5 Epilachna beetle (Epilachna sp) Nature of damage
Both adults and larvae damage the leaves by eating the soft outer tissue and leaving windows in the leaves. Leaf tissue eaten between veins.
Usually the eggs, larval and nymphal stages are attacked by predators and parasites. Hence use insecticides judiciously to conserve the natural enemies. Removal of egg masses found on the lower surface of the leaves. Use recommended insecticides like Trichlorfon 500g/l EC as a drenching spray when damage is observed.
Root knot nematode (Meloidogyne sp): Discuss under common pests
Aphids (Aphis gossypi) and Leaf hoppers (Amrasca devatans) Thrips (Scirtothrips dorsalis) and Leaf miner (Liriomyza sativa) and Mites (Hemitarsonamus latus, Tetranychus spp): See details given under common pests.
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Shoot and pod borer (Leucinoides orbonalis) Nature of damage
The damaged shoots bend and wilt. When such shoots are split open, larvae can be seen inside. The larvae bore into the fruits and start eating from inside. There may be darkened holes surrounded with brownish areas on the fruit surface The feeding tunnels inside the fruits are hollow and filled with frass.
Use recommended spacing. Erect a 2m high mechanical barrier with material like woven coconut leaf to avoid the movement of adult in to the field. Destruction of damaged shoots and fruits. Dispose the stubble after harvest. Use recommended amount of fertilizer. Use recommended insecticides like; Carbofuran 3% GR, Carbaryl 85% WP, Carbaryl 480g/l SC, Etofenprox 100g/l EC, Permethrin 250g/l EC, Esfenvalerate 75g/l EC, Fenvalerate 200g/l EC, Beta-Cyfluthrin 25g/l EC, Deltamethrin 25g/l EC, Spinosad 450g/l SC, or Chromafenozide 50g/l SC. Apply Carbofuran to planting holes and other insecticides at flowering.
Leaf roller (Psara bipunctalis) Nature of damage
The caterpillar rolls the leaves and feed on the leaf tissue except on the veins. Damage mostly observed on the terminal shoots.
Collection and destruction of infested leaf roles with the caterpillar. Use recommended insecticides like Etofenprox 100g/l EC and Imidacloprid 200g/l EC.
3 4 5 6
White fly (Bemisia tabaci,) Leaf hoppers (Amrasca devastans) Thrips (Scirtothrips dorsalis) Mites (Tetranychus spp:): See details given under common pests.
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Pod borers (Spodoptera litura, Helicoverpa armigera) Nature of damage
The adult female of Spodoptera Sp. is a brown coloured moth who lays eggs on the under surface of the leaves in batches. The emerging larvae feed initially on the young leaves and flowers. Later they feed on the fruits by making irregular holes. The female of Helicoverpa sp. is also brown coloured, who deposit eggs singly on the lower surface of leaves. Then larvae make circular holes on the fruits and feed inside the pods by keeping anterior part of the body inside the pod and rest of the body projecting outside.
Destroy the affected plant parts. Hand picking of the caterpillars. Field sanitation by proper weed control and removal of the stubble. Use recommended insecticides (Chlorfluazuron 50g/l EC, Thidicarb 375g/l SC, Thidicarb 75% WP Methomyl 180g/l SL and 40% SP).
2 Cut worm (Agrotis sp) 3 Thrips (Scirtothrips dorsalis) 4 White fly (Bemisia tabaci): under common pests 5 Mites (Tetranychus sp) See the details given under common pests Okra
Shoot and pod borer (Earias vitella) Nature of damage
Extensive tunneling by the larvae will result in the wilting of the top leaves and the collapse of the apex of the main stem. When fruiting starts, larvae move to flower buds, tiny fruits, and eventually the mature pods. Severe attack causes the shedding of flower buds and reduced yield. When attacking the fruit, the larvae feed on the milky seeds and other contents of the pod, leaving excrement-filled tunnels.
Hand picking and destroying of larvae. Disposal of affected shoots and pods. Use of recommended insecticides like Tebufenozide 200g/l SC, Carbaryl 85% WP. Carbaryl 480g/l SC Use insecticides if the damage is severe.
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Leaf roller (Sylepta derogata) Nature of damage
S. derogata caterpillars roll leaves and eat the leaf margins, causing the leaves to curl and drop.
Collection and destruction of rolled leaves. Use of recommended insecticides like Carbaryl 85% WP or Carbaryl 480g/l SC. Follow the recommendation of the label when using insecticides. Use insecticides if the damage is severe.
Red cotton bug (Dysdercus cingulatus) Nature of damage
The adult is red or yellow insect with black markings on the wings. The adult and the nymphs suck sap from shoots, leaves and pods.
Use of recommended insecticides like Carbaryl 85% WP or Carbaryl 480g/l SC if the damage is severe. The damage is significant when crop is used for seed purposes.
4 Leafhoppers and white fly also damage
See details under common pests.
5 Mites :
Details given under capsicum and common pests
Cow pea and Bean
Bean fly (Ophiomyia phaseoli) Nature of damage
Large number of feeding and oviposition punctures are found on the upper leaf surface which appears as yellow spots. Numerous larval mines are found on the underside of the leaves which appear as silvery, curved stripes. Stems are often thicker than normal and cracked lengthwise just above the soil line where fly pupate. In cases of heavy infestation, many plants die.
Ridging the crop 2-3 weeks after germination helps to cover the adventitious roots which are produced by O. phaseoli damaged plants. and reduces the plant mortality. Use Thiamethoxam 70% WS for treating the seeds or spray Carbosulfan 200g/l SC, Oxydemeton-methyl 250g/l EC, Formothion 330g/l EC, or Diazinon 500g/l EC/EW at 2-leaf stage. - 161 -
Pod borers (Maruca testulalis,
Helicoverpa armigera, Lampides boeticus)
Nature of damage
Helicoverpa spp was discussed under capsicum and Maruca testulalis and Lampides boeticus are discussed under pulses.
See details given under capsicum and Pulses.
Aphids (Aphis cracivora): See details given under common pests.
1 Diamond back moth (DBM) (Plutella xylostella), 2 Cabbage web worm (CWW) (Hellula undalis), 3 Cabbage Heart Caterpillar (CHC) 4
Cabbage looper (CL) (Plusia eriosoma), Spodotera litura Nature of damage
The nature of damage depend on the caterpillar species. The most common damage is leaf damage in the from translucent windows or holes. Frass and faecal matter may be present on the developing head damaged by caterpillars.
Conservation of natural enemies by judicious application of insecticides. Use insecticides only when the number of DBM larvae exceed 80 or 4 larvae for other caterpillar species in 12 randomly chosen plants. Neem seed water extract is very effective on cabbage caterpillars. The details of the preparation is given under leaf miner. (Common pests). The recommended insecticides are Tebufenozide 200 g/l SC, Chlorfluazuron 50g/l EC AzaÂŹ dirachtin 50g/l SL, Etofenprox 100g/l EC, Profenophos 500g/l EC, Lufenuron 50g/1 EC, Chromafenozide 50g/l SC, Emamectin benzoate 5% SG, Indoxacarb 150g/l EC, Spinosad 25g/l SC.
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Fruit borer (Heliothis armigera) Nature of damage
Details given under capsicum.
Discussed under capsicum.
2 Root knot-nematode (Meloidogyne sp): Discussed under common pests.
Potato tuber moth (Phthorimaea operculella) Nature of damage
In growing plants presence of leaf mines indicate the presence of larvae. Additionally, the stem is broken or weakened. On tubers, detection is more difficult without cutting open some tubers, when galleries and larvae will be apparent within the potatoes.
For field infestation use Carbaryl 85 WP or Carbaryl 480 SC. Direct spray on to the underside of the foilage. Clean the potato store well before storage. Apply residual spray emulsion of one of the following insecticides like Prothiophos 500g/l EC, Acetamiprid 20% SP, Novaluron 100g/l EC Pirimiphos-methyl 500 g/l EC on to the walls and storage trays before potatoes are stored. For seed potatoes use Thiocyclam (hydrogen oxalate) 50% SP.
White grub (Melolontha spp and Anomala spp) Nature of damage
The grub feed on roots which results in wilting of plants.
Use recommended insecticides like Chlorpyriphos 200g/l EC or Chlorpyriphos 400g/l EC. Apply Isofenphos 5% GR to planting holes and Chlorpyrifos as a soil drench.
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Potato cyst nematode 3
Nature of damage
Affected plants show poor growth and exhibit symptoms of water and/ or mineral deficiency stress. Leaves are yellow and wilted. Roots of infected plants exhibit minute, white bodies, which are the erupted immature females through the root epidermis.
Crop rotation with non-solanaceous crops. Application of Calcium hypoclorite 70% to furrows at planting or one day before planting.
Green peach aphid (Myzus persicae) Nature of damage
The major damage caused by green peach aphid is through transmission of plant viruses. In potato, Potato leaf roll virus symptoms are leaf rolling and tuber stem necrosis.
Use recommended insecticides Dinotefuran 20% WP, Imidacloprid 200g/l SL, Carbaryl 480g/l SC, Thiamethoxam 25% WG, Thiacloprid 240g/l SC, Imidacloprid 70% WG, Ethiprole 100g/l SC, Thiocyclam (hydrogen oxalate) 50% SP, Dimethoate 400g/l EC, Carbosulfan 200g/l SC and Quinalphos 250g/l EC. Time insecticide application by monitoring aphid population in water traps placed in the field. At low population apply as spot application. Dimethoate is incompatible with sulphur based formulation. Discussed under common pests.
4 Leaf miner, Liriomyza huidobrensis: See details under common pests.
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Leaf hoppers (Amrasca devastans) Nature of damage
The green coloured adult insect is triangular shaped and very active and found on the underside of the leaves. The adult and nymphs suck the sap from the leaves. The margins of the damage leaves turn yellow and roll upwords. Later brown coloured triangular burnt like areas develop.
Field sanitation by proper disposal of the crop residue and weed control Use only the recommended insecticide properly to conserve the natural enemies. The recommended insecticides are Acephate 75% SP or Acetamiprid 20% SP.
Aphids (Aphis gossypii, Aphis craccivora, Myzus persicae, Rhophalosipum maidis and Brevicoryne brassicae) Nature of damage
Leaf rolling, yellowing or deformation may result when the population is high. Sooty moulds develops on the foliage as result of the production of honey dew.
Field sanitation by proper disposal of the crop residue and weeds. Removal of the plant parts infested with aphids and destroying the insects by putting them into a soap solution. This is very useful method in the home gardens. Use a stream of water to detach the aphids from the foliage. Use recommended insecticides; Imidacloprid 70% WG, Imidacloprid 200 g/l SL Thiamethoxam 25% WG, or Dimethoate 400g/l EC. Dimethoate is incompatible with Sulphur containing compounds. Direct the spray on to the underside of the foliage.
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White fly (Bemisia tabaci,Trialeurodes vaporariorumand Aleuroidicus sp)
Nature of damage
The adult is silvery white in colour often found under side of the leaves where it suck the sap. When there is high population plants may wilt, turn yellow and die. White fly also secrete honey dew where mould fungi grow and the leaves may turn black in colour.
Destroy the crop residue that harbour the white fly. Raise seedlings under the protection of nettings to prevent infestation by the viruses vectored by the white fly. Avoid unnecessary application of insecticides to prevent secondary outbreak of white fly due to the elimination of the natural enemies. Use recommended insecticides like; Acetamiprid 20% SP, Thiamethoxam 25% WG. Imidacloprid 70% WG or Imidacloprid 200g/l SL. Follow the recommendation of the label when using insecticides. For potato white fly following insecticides; Dinotefuran 20% WP, Thiacloprid 240g/l SC, Imidacloprid 70% WG, Ethiprole 100g/l SC or Thiocyclam (hydrogen oxalate) 50% SP are recommended.
Thrips (Scirtothrips dorsalis, Thrips palmi, Frankliniella spp. and Selenothrips rubrocinctus)
Nature of damage
The adults and the nymphs suck the sap from leaves and flowers. As a result leaves may roll along the margins and flowers may drop.
Field sanitation by proper disposal of the crop residue and weeds. Excessive use of fertilizer which increase vegetative growth beyond the normal needs of the plant should be discouraged Avoid discriminate use of pesticides to conserve predatory mites and other natural enemies. Use recommended insecticides; Imidacloprid 200g/l SL, Imidacloprid 70% WG, Thiamethoxam 25% WG or Fipronil 50g/l SC. Follow the recommendation of the label when using insecticides. Apply insecticides in the evening. For potato thrips, Thrips palmi, the recommended insecticides are Dinotefuran 20% WP, Imidacloprid 200g/l SL, Fipronil 50g/l SC, Carbosulfan 200g/l SC, Thiacloprid 240g/l SC, Imidacloprid 70% WG, Ethiprole 100g/l SC or Thiocyclam (hydrogen oxalate) 50%.
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Leaf miner (Liriomyza sativae) Nature of damage
The feeding by the larvae below the upper epidermis results in serpentine mines on the leaves.
Wash away the pupa found on the leaves during irrigation. Use polythene mulch to collect the falling pupal cases to avoid them entering the soil. Use only the recommended insecticides to preserve the natural enemies. Use yellow coloured polythene applied with grease to attract the adults. Use neem extract to repel the adults from ovi-position. Prepare the neem water extract by mixing 50 g of neem powder in 1l of water and keeping it over night. Following, day strain the mixture and apply with little soap solution. Recommended insecticides are Cyromazine 75% WP, Azadirachtin 50g/l SL, and Abamectin 18g/l EC.
Cut worm (Agrotis sp) Nature of damage
Larvae can do considerable damage by severing young plants at the base.
Deep plough the land to destroy different life stages of the insect. Before planting, keep the field flooded with water to destroy the different life stages. Use one of the following recommended insecticides; Profenophos 500g/l EC, Prothiophos 500g/l EC, Chlorfluazuron 50g/l EC, Etofenprox 100g/l EC or Carbofuran 3% GR. Apply around the base of the plant to saturate the soil just after transplanting. Apply carbofuran to the planting holes.
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Mites (Hemitarsonamus latus, Tetranychus spp) Nature of damage
Mites feed by piercing plant cells and sucking up the sap that oozes from the wound. Feeding damage causes terminal leaves and flower buds to become cupped and distorted. As a result of feeding injury, corky brown areas appear between the main veins on the underside on the leaf. Young foliage sometimes becomes rust colored and nearly always is deformed. Mites of Tetranychus spp are protected by fine webbing.
Use recommended insecticides in a proper way and fewer times to conserve natural enemies. Maintenance of good field hygiene by weed control and disposal of crop residue. Maintain the plant vigor by the application of fertilizer and irrigation. The recommended chemicals are Azadirachtin 10g/l EC, Sulphur 80% WP/WG, Abamectin 18g/l EC, Hexythiazox 10% WP or Flufenoxuron 100g/l DC. Direct spray on to the under side of the foliage. Do not use Sulphur on cucumber.
Root knot nematode (Meloidogyne sp) Nature of damage
Plant get stunted. The leaves turn yellow. When such plants are examined root knots can be observed
Crop rotation with non-hosts like leeks, onion and cereals Add organic manure such as poultry manure (10t/ha) or green manure like wild sunflower. Use recommended pesticide like Carbofuran 3% G, Benfuracarb 3% G or Phenomiphos 5% G.
Post harvest pests Large number of microorganism, insect pests and mites are responsible for post harvest losses in crop plants. In cucurbitaceous vegetables and fruits like mangoes and banana fruits can be infested by fruit fly while green vegetables can be affected by thrips and mites. Rats can also be problem in storage. In cereals and pulses are infested by rice moth, Sitotroga cerealella, Rice weevil, Sitophilius oryzae, red flour beetle Tribolium castaneum and pulse bruchids, Callosobruchus spp. Ware houses are treated with insecticides like Pirimiphos methyl directing the spray on to the walls. Additionally bags should turned inside out and sprayed and air dried before use. For bruchid control in seed crops seed treatment with Pirimiphos methyl 2% DP is recommended. - 168 -
Disease control strategies for drought Disease in general
Plant disease is an interaction between host, pathogen and environment. Therefore, flooding and drought conditions certainly have impact on diseases. Environment (Flood, Drought)
Certain diseases are more likely to occur because of drought and flood related stress on the plants. These conditions may favour for certain infections, disease development and/ or disease spread. In other cases above conditions may not have impact on the pathogen at all but may exacerbate the damage caused by disease in such abiotic stressed plants. The floods or droughts may affect the susceptibility of the host and survival, vigour, rate of multiplication, sporulation, dispersal, spore germination and penetration of the pathogen. Sometimes flood or drought conditions may predispose the diseases develop into epidemic conditions. This had often experienced after floods or prolonged drought conditions. They have caused famines and mined the economics of several countries. The most important environmental factor for disease development is moisture (excess or less ie. floods and drought).
Drought conditions In drought conditions plants show symptoms of wilting, leaf burn, leaf folding and abscission and physiological responses including changes in RNA metabolism and protein synthesis, enzymes, isoenzymes and plant growth regulators. These changes will affect susceptibility to pathogens. However, some pathogens especially certain fungi may produce large number of spores and cause increased infections in drought conditions.
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Therefore, interaction of reduced host plant resistance and increase in inoculum potential would increase some disease incidences. Therefore, plants are affected by multiple stress i.e. drought and diseases (abiotic and biotic stresses). Diseases may occur during or after drought stress. Certain diseases may be enhanced by drought and some others may be induced. Drought conditions may predispose (increase susceptibility to diseases) plants to some diseases. Mechanism of predisposition â&#x20AC;&#x201C; In dehydrated plants, photosynthesis would be reduced and protein synthesis altered and thus provide improved substrates for pathogen (eg. Nitrogen) and defensive compounds like photoalexins and enzymes would be decreased. eg. Powdery mildews, Cankers. Nevertheless populations of many vectors of virus and phytoplasma diseases (viz. thrips, white flies, plant hoppers, mites etc.) would increase rapidly in drought conditions. Those diseases would increase up to epidemic levels in dry seasons, mainly at the dry zone during Yala season with drought condition.
Diseases occur frequently in drought conditions Fungal diseases
Fungal wilts and rots caused by Fusarium sp., Rhizoctonia spp. and Sclerotium spp. Symptoms
Plants infected at the seedling stage usually wilt and die soon after appearance of the first symptoms. In older plants leaf epinasty followed by stunting of the plants, yellowing of lower leaves, wilting of leaves and twigs, defoliation (mainly in drought conditions) and final death of the plants occur. Roots and base of the plant may become infected and rotting with white mycelia of Fusarium spp. or Sclerotia of Rhizoctonia spp. or Sclerotium spp. may be visible.
Hosts : Vegetables, fruits and other field crops. Epidemiology
Fungi survive in soil and in plant debris and spread through soil, water and infected planting materials. Fusarium spp. produce chlamidospores Sclerotium spp. produce Sclerotia spp. produce sclerotia in drought conditions. - 170 -
Management strategies Cultural control
1. Sterilize or burn nursery soils before planting. 2. Crop rotation with non-susceptible hosts. 3. Remove infected plants branches and destroy them.
Same fungicides used for seed and soil treatment in page.
Trichoderma spp. is used as soil application.
Powdery mildew caused by Oidium spp. and Erysiphae spp. Spaerotheca spp., Leveillua spp., Podaspharea spp. Symptoms
Almost all above ground parts of the plants are affected by this disease. White powdery coating (conidia) form on one or both sides of the leaves and become distorted. These areas become purplish yellow and eventually necrotic. Flowers and young fruit may be covered by the powdery spore masses resulting in brown shriveled necrosis. Young fruits may drop off.
Hosts : Vegetables, fruits and other field crops. Epidemiology
Powdery mildew is most severe in dry weather. Conidia are wind disseminated and positively correlated with temperature and negatively correlated with humidity, vapor pressure deficit and leaf wetness. Fungal mycelia grow on the surface of plant tissues and obtain nutrients by producing haustoria into the epidermal cells.
Spraying of wettable sulphur 80% WP/WG is the most cheapest and safe fungicide however spraying should be started at the early stages of infection to achieve good control. Other fungicides that could be used are Bitertanol 300g/l EC, Carbendazim 50% WP/WG or 500g/l SC, Thiophanate methyl 70% WP or 500g/l SC, Chlorothalonil 500g/l SC.
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3 Common scab of potato caused by
Streptomyces scabies Symptoms
This disease causes symptoms in tubers. Infected tubers first develop small, brownish, raised spots. Later, the spots usually enlarge, coalesce and become corky. Lesions extend 3-4mm. deep in the tubers. Lesions may appear as rusted areas or raised areas with depressed centres covered with corky tissues.
Hosts : Potato, beet, radish and other root crops. Epidemiology
The pathogen can survive in soil indefinitely except in acidic conditions. It spread through soil, water or infested tubers. It penetrates through lenticels, wounds and stomata or in young tubers directly. Young tubers are more susceptible. Scab incidences are high in drought conditions and when soil pH is high.
Management strategies Cultural methods
1. Use disease-free tubers. 2. Crop rotation with non-susceptible hosts. 3. Plough the soil and add green manure to enhance growth of antagonistic microorganisms. 4. Irrigate the soil at tuber initiation and until about 4 weeks afterwards. 5. Decrease soil pH using sulphur. 6. Use of resistant/ tolerant varieties.
Virus and Phytoplasma diseases Virus diseases transmitted by insect vectors are more common in dry or drought conditions as most of the insect vector (viz. aphids, thrips, white flies, mites and leaf hoppers) populations increase rapidly during dry spells. Insects with sucking mouthparts carry plant viruses from an infected plant and transmit to another plant. The method of transmission may be nonpersistent, semi-persistent, persistent or propagative manner.
1 Bean common mosaic virus Symptoms
Leaves show mottling, yellowing and malformation of leaves and pods occur. Infested plants may be stunted and bushy, seeds may be aborted, smaller or malformed pods occur. Quality and quantity of yield would be reduced.
Hosts : Beans - 172 -
Transmission is through several aphids, seeds and pollen.
Management strategies 1. 2. 3. 4.
Use disease-free seeds. Use resistant varieties. Control aphids using recommended insecticides. Rogue out infected plants and destroy them.
Cucumber mosaic virus Symptoms
Cause mottling, discolouration of leaves, flowers and fruits. Plants get stunted and quantity and quality of yield are reduced.
Hosts : Many crops and weeds. Epidemiology
Transmission is through several aphids in non-persistent manner and mechanically by sap.
1. Use resistant varieties. 2. Rogue out infected plants and destroy them. 3. Use recommended insecticides to control aphids.
Chilli leaf curl complex Symptoms
Leaves become mottled and distorted due to virus infection, upward curling due to feeding by thrips or downward curling and bronzing due to feeding by mites. Plants get stunted, flowers and fruits distorted and quantity and quality of yield reduced.
Hosts : Chilli
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Leaf curl virus is transmitted through whiteflies. White fly, thrips and mite populations increase rapidly in dry weather and leaf curl complex infection increase.
1. Use resistant varieties. 2. Rogue out infected plants and destroy them. 3. Use recommended insecticides to control the insects.
Drought escape strategies As a prior requirement, timely land preparation is essential at the proper soil moisture regime on RBE soils. Delay in land preparation will delay the crop establishment which ultimately result in unfavourable seasonal impacts like excessive rains at harvesting, moisture stress at flowering or high pest and diseases incidences. Since the farmer has to wait until the rain comes for land preparation he can go for zero tillage or minimum tillage which avoids heavy dependency on rain water for land preparation. Another alternative is to use a non selective herbicide to clear the land which facilitates death of all the weeds within a short period of time so that seed establishment can be done with the rains. Time of planting is a crucial factor for cultivating of crops avoiding dry periods. For example to mitigate leaf curl complex in chilli and thrips attack in onion the crop should be planted early yala. (For chilli last week of April and for onion first week of May). Legumes may also be severely infected with viruses when it is planted late, especially in the yala season. The Walagambahuwa concept was developed to maximize the utilization of incidental rainfall for rice cultivation while reducing the crop failures due to shortage of water at the tail end of the cropping season. The underlying principle was the utilization of incidental rainfall in maha cultivation through advancing the timing of field operations for rice and save water for rice/ OFC cultivation in subsequent yala season. There are no locally released OFC varieties having appreciable tolerance to adverse moisture or temperature conditions. However, short age varieties have been developed as an escape mechanism to alleviate from drought situations. Examples for such shortage varieties include the maize variety Aruna (90 days), Black gram variety Anuradha (65-70 days) Mungbean variety, MI-6 (55-60 days), Soybean variety Pb 1 (80-85 days) and Groundnut variety Tissa (90 days) Vegetable cowpea (45 days).
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Agronomic management for OFC Minimize dry conditions by timely irrigation if supplementary irrigation is available. Except for rainfed farming situations, try to find a supplementary water source as much as possible when drought susceptible crops are grown. Except Gingelly, Finger millet, Blackgram all other OFCâ&#x20AC;&#x2122;s require sufficient water to give a high productivity As a means of maximizing incidental rainfall and to mitigate the effects of periodic droughts on crop growth, conservation farming practices will be very useful. This can be achieved through proper land management and preparation, mulching etc. It has been found that the use of Gliricidia (10 tons/ha) or straw (5 tons/ha) as a mulch after crop establishment reduced fertilizer requirement by 25%. Other advantages of this practice will be moisture conservation and suppression of weed emergence. Another conservation strategy is the cultivation of annual crops between perennial leguminous tree species commonly named as Alley cropping. Soil erosion control under intensive rainy conditions, nutrient recycling, weed control, improvement in biodiversity as means of natural pest management systems are other benefits obtained in this system Organic farming approach is also useful in addressing the issues related to water shortages. Soil organic matter improves and stabilizes the soil structure so that the soils can absorb higher amounts of water without causing surface run off and improving the water retention capacity to mitigate drought conditions. Low tillage, maintenance of permanent soil cover through crops, crop residues, cover crops, crop rotation increases the soil organic mater. Mulching and zero tillage are appropriate where rainfall intensity is low. Selection of crops should be carried out toappropriate for the particular farming environment. For example Maize is a crop having high water use efficiency and therefore it can be grown successfully under rainfed conditions. Finger millet and gingelly are comparatively drought tolerant and less water demanding crops. They are suitable for yala cultivation in paddy lands. Further, gingelly is traditionally popular as a rainfed crop for uplands. There are varieties suitable for each season with respect to some crops. For example, some varieties are not suitable for maha season even though farmers are willing to cultivate them. Therefore, selection of appropriate varieties for each cultivation season is important. For example finger millet variety Oshada is suitable for both maha and yala but other finger millet varieties are recommended for yala cultivation. These varieties can be grown in paddy lands in yala whenever water availability of rice, other field crops or vegetables are not adequate. There are nearly 185,000ha of irrigated lands in the command area of minor tanks of which 50% of minor tanks are abandoned due to lack of water for paddy cultivation. These fallow paddy lands will provide a high potential for other field crop production (finger millet cultivation) during Yala season. Cropping patterns and relevant management practices to maximum utilization of the available moisture have been introduced. For example, it has been identified less water demanding crops like finger millet and - 175 -
sesame as suitable for the rice based cropping systems and short age crops for mid seasons cultivation at minimum level of inputs. Crop diversification along with perennials is another option to mitigate impacts from unexpected weather conditions because agro biodiversity increases resilience to changing environmental condotions and stresses. Famerâ&#x20AC;&#x2122;s attitudes must develop towords the efficient utilization of available rainwater or irrigated water along with the suitable techiques such as micro level rain water harvesting systems for OFCs. The method of the irrigation mainly depends on the water source, cultivation extent, capital, crop, and specifically on type of soil available in the area. Basically in Sri Lanka the irrigation water supply is carried out by sending water to the agricultural area under gravity to practice irrigation. This is the cheapest way of irrigation but careful selection of on-farm irrigation method is needed to acquire reasonable irrigation efficiency, uniform distribution and to reduce the water loss. Basin irrigation, Ridge and furrow irrigation, and bedded basin irrigation are the most common on-farm irrigation methods used in the dry zone area. However, depending on the great soil group water saving irrigation methods such as drip irrigation or sprinkler irrigation systems particularly under agro well farming has to be selected to minimize the water losses. Since the water holding capacity of RBE soils is fairly high,deep rooted other field crops can be grown with longer irrigation intervals. The wind of south west monsoon reaches the dry zone after passing the central hills as a dry wind named as kachchan. To avoid its effect on dry land farming it is better to establishment of wind barriers by using some multipurpose tree crops or other economic timber crops specific to the dry zone conditions. Adjusting planting density can be used as a drought escaping tool in some crops to increase the unit area yield per unit time.For example, chill can be cultivated under supplementary irrigated condition at 60cm X 15cm spacing where the farmer can get more yield within a limited number of picks instead of maintaining the crop for more pics. Timely inter-cultivation is necessary in some crops in order to accelerate the growth so that the crop will come to flowering following a good vegetative growth without a delayed harvest. Extending the nursery period under delayed rain or drought conditions. For example chilli plant can be kept in the nursery for about 50-55 days before field establishment instead of planting it after 30-35 days in the nursery. Produce into another form. For instance, instead of dry chill harvesting green chilli can be harvested towards the end of the crop if the rainfall distribution is suspected to be poor. In the case of onion, if rain is not adequate to go for a bulb crop, it is advisable to harvest it as a vegetable. - 176 -
Impact of drought on weed growth, herbicide performance and weed management strategies Weeds compete with crop plants for soil moisture, nutrients and light. Competition for water between crops and weeds increases as soil moisture becomes limited and hence control of weeds becomes more important when water is scarce. Prolonged dry weather has a direct bearing on several aspects of weed growth and management including weed germination, growth and hardiness, weed-crop competition, mechanical weed control and ultimately chemical weed control. Weed germination and emergence is either inhibited or delayed under dry conditions, thus early season drought may sometimes reduce weed infestations. As a result weeds that normally would emerge during the growing season and be controlled prior to planting may not emerge until later of the season. Drought that occurs after weed emergence toughens or hardens the weeds, making more difficult to control them. Weed response to severe drought stress include leaf cuticle thickening, reduced vegetative growth and rapid flowering. Further these weeds develop extensive root systems early and take advantage of limited surface soil moisture making them more competitive. Development of these plant characteristics are varied within different weed species and as a result certain weeds become comparatively more efficient over the other in capturing resources. Thus drought tolerant grasses, sedges and broadleaves may become more aggressive over the other weeds depending on the degree of moisture stress and the cropping situation (lowland or upland).
Drought tolerant common weeds Grass species :
Cynadon dactylon, Panicum repens, Ischeameum rugosum, Elusine indica, Panicum maximum, Echinochloa crussgalli, Dactyloctenium aegyptium, Cenchrus echinatus Cynadon dactylon
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Cyperus species: Cyperus rotundus
Commerlina benghalensis, Cyanotis species, Amaranthus spinosus, Mimosa pudica, Portulaca oleracea, Boerhavia diffiusa Commerlina benghalensis
Delayed period of emergence coupled with shift of the weed flora from normal to hardy and more competitive weeds alters the normal critical period of cropweed competition resulting s greater weed competitive pressure on crops than that during adequate soil moisture conditions. The combined effect of drought and heavy competition from weeds severely affect on crop growth resulting poor yields. Tillage is basically aims at eliminating weeds both before as well as after crop establishment. Thus seed bed preparation is critical for elimination of established weeds before planting. However pre-plant tillage depletes soil moisture and multiple tillage operations may reduce available soil moisture to marginal levels, resulting in poor crop stands. Eliminating pre-planting tillage across the fields with conservation tillage, minimum tillage or no tillage systems conserves the soil moisture and improves soil conditions for effective stand establishment. Reduced tillage, however, is not advised to practice continuously as it allows the proliferation of hard to control perennial weeds. Cultivation of row crops remains an option for weed control during dry conditions. - 178 -
Adoption of shallow inter-row cultivation with simple tools is beneficial to control small weeds and loosen crusted soil, particularly, when options for chemical weed control become inappropriate under drought conditions. However, cultivation for weed control during extreme dry conditions may be detrimental due to further loss of critical soil moisture resulting in poor crop stand. Chemical weed control may be considerably affected by dry weather. Significant effects can be observed on pre and post emergence herbicides. Usually, effectiveness of pre-emergence herbicides is largely dependent on the degree of soil moisture, determined by either rainfall or irrigation, for activation or movement into the zone of weed seed germination. Sunlight degrades pre-emergence herbicides on the soil surface if it is not activated by water and moved into the soil. Even for highly persistent herbicides, failure to move the compound into the soil due to lack of rainfall allows weeds to germinate just after planting. Herbicides applied to dry soils may be so tightly bound that they become unavailable for uptake by plants and for leaching. Dry soil conditions can also prevent chemical and biological processes that degrade herbicides making them more likely to persist and injure subsequent crops. Post emergent herbicides seem to be a viable option to soil applied herbicides, especially with dry weather. These herbicides perform best when weeds are actively growing. High temperature, high relative humidity and adequate soil moisture are ideal for active growth of weeds. Efficacy of post emergent herbicides, particularly, those that are translocated within the target weed are highly dependent upon active plant growth. Typically, better the growing conditions, better the performance of post emergence herbicides. Efficacy of post emergence or foliage applied herbicides, particularly, those that are translocated within the plant, is reduced when plants are water stressed. As a result, movement weedlcides within the target weeds from site of absorption to the site of action are reduced. Once the movement of herbicides with sugars or water stream within the target weeds is weakened, control is likely to be reduced. Absorption of foliar applied herbicides may also be interfered with drought. Drought stressed plants produce thicker leaf cuticle to help reduce moisture stress. The thick cuticle so developed may act as a barrier for effective absorption of herbicides resulting weeds become more tolerant to post emergence treatment because of decreased herbicide absorption. Addition of proper adjuvants/ spray additives would improve coutrd of drought stressed weeds by improving herbicide spray coverage, retention and uptake. Selection of appropriate adjuvants depends on the herbicide, growth stage of crop and weeds and environmental conditions. Individual herbicides may require different adjuvants for best performance. Separating grass and broadleaf control herbicides will help prevent herbicide antagonism ensuring a better weed control. On the other hand improper use of spray additives can reduce weed control or increase crop injury. Drought stress affects many plant processes, resulting in poor translocation of herbicides within the plant to the site of action. In general, more herbicides is needed to control drought stressed weeds than non stressed weeds while reduced herbicide rates are less likely to perform well under conditions of drought stress. - 179 -
Most contact herbicides, eg. Paraquat, become more active as temperature increases. Increased activity may provide improved weed control, but can also result in greater crop injury. The best control from contact herbicides is generally achieved with through spray coverage and application to small seedling weeds. Although waiting until temperature subsides will lessen the crop injury, the weeds may develop beyond the optimum treatment stage if application is delayed too long. Application of systemic herbicides such as glyphosate, 2.4.D, MCPA, whip super etc. early in the morning after plants have recovered from the heat of the previous day provide better weed control than afternoon or evening application. Drought may also influence herbicide carryover. Soil microorganisms play a significant role in degradation of many pesticides. Activity of soil microbes is favored by warm, moist conditions. Under dry conditions, microbial degradation slows down and herbicide persistence in the soil is extended. This is further favoured by reduced chemical breakdown under reduced soil moisture conditions. For long- residual products which have specific restrictions relating carry over, persistence is greater for incorporated rather than surface application. Weed control under drought stress conditions Basically, weed control during crop production comprise of two main stages as pre- planting and post planting weed control. Pre-planting weed control is alternatively described as land preparation where seed bed is prepared after removing all in situ weeds. During rice cultivation, common and widely adopted method of land preparation is wet tillage where fields are ploughed and harrowed followed by leveling under wet conditions. This process requires a considerable amount of water- around 150-25mm. Advantage of wet tillage is that the standing weed biomass is being subjected to decay under inundated conditions after giving inversion tillage. The anaerobic soil atmosphere created by the process helps to kill the weeds and subsequently to decay them. However, under water shortage conditions wet tillage does not ensure a good weed control and under such circumstances, dry tillage, minimum or zero tillage options becomes significant in which control of standing weed biomass is less dependent on water, but primarily upon effective herbicides. Pre-plant weed control Dry tillage â&#x20AC;&#x201C; if the soil moisture is sufficient to till the land, 2-3 passes of non inversion tillage may be adopted. However if the standing weed biomass is appreciably high, application of a systemic or contact total herbicide depending on the weed composition prior to tillage is advantageous. If the weed flora is dominated by annuals and is in actively growing stage, application of Paraquat may suffice to desiccate the weeds and land can be tilled after one to two days of the herbicide application. Conversely, if the perennial weeds are predominant, it is advisable to apply a total systemic herbicide is. Glyphosate and wait for about one week to initiate the tillage operations. Minimum or conservation tillage â&#x20AC;&#x201C; Initially a total foliar herbicide is applied on to actively growing weeds. If drought conditions are severe, application - 180 -
in the early hours of the day ensure a better absorption of the herbicide into weeds. Herbicide absorption can be enhanced with the use of compatible additives. Using an N-based additive (like ammonium sulphate) or adjuants may help increase herbicide absorption into target weeds. In lowland conditions, wait about 2-3 days after application to impound water into the fields for harrowing and puddling. Zero tillage - The standing weed biomass is entirely desiccated by herbicides and no tillage operations are adopted. Apply a systemic total herbicide (Eg. Glyphosate) in the early hours of the day, leave about 710 days to totally scorch up the weeds and follow up with either planting or seeding of the crop on the weed mulch using an appropriate seeder with the right soil moisture conditions. Zero tillage could beadopted for cultivation of both lowland rice and the upland crops as well. It is important to control all in situ weeds during pre-plant weed control. Removal of perennial weeds along with their vegetative propagules is essential during tillage as weeds emerging from vegetative propagules after crop establishment are extremely difficult to control with herbicides. Under such circumstances, the only option is manual weeding which not quite successful in drought conditions. Post planting weed control Usually post plant planting weed control in rice is largely facilitated through maintaining standing water for about 2-3 inches during first 4-5 weeks period of crop growth. However periodic drought condition due to erratic rainfall or inadequate availability of irrigation water during this period promotes a prolific weed growth and consequently demands alternative strategies that are less dependent on standing water to control weeds. Under such circumstances, either mechanical or chemical weeding could be successfully adopted. Mechanical weeding Establishment of the crop in rows becomes a pre-requisite for mechanical weeding. Fields prepared employing dry or minimum tillage can be row seeded using suitable seeders under dry or wet conditions. Various row seeders developed by FMRC can be used for dry seeding with a two wheel tractor under upland conditions. In zero tilled fields seeds can be either row seeded or dibbled with a rolling injection planter. Drum seeder can be effectively adopted to establish row seeded rice crop in wet seeded paddy. After emergence of the crop, emerging weeds should be removed before reaching them to critical period of crop-weed competition. Usually under low moisture levels, weeds emerge faster than under standing water conditions in lowland rice and hence crop/ weed competition starts early during the crop growth. Thus weeding should be commenced around 1012 days of rice emergence and followed by 20-25 days. Several efficient inter-row weeders are available for mechanical weeding in row seeded rice (eg. Swiss hoe, wheel hoe, Japanese weeder). The same principles can be adopted to remove weeds in upland crops as well. - 181 -
Chemical weed control Two different types of herbicides are available for selective control weeds. Those that are applied before emergence of weeds are called pre emergent herbicides while the others which are applied after weed emergence as post emergent herbicides. Pre emergent herbicides should be applied only on wet soil before emergence of weeds .Thus for dry-seeded rice, pre-emergence herbicides could be applied after adequate rains have received to germinate weeds. On the other hand, for wet seeded rice, pre emergents can be applied on to moist/ wet soil after seed broadcasting or row seeding provided that soil surface is moist enough to germinate weed seeds. The same procedure can be adopted for transplanting as well. Periodic drying of the soil surface reduces the efficacy of herbicides and under such circumstances either manual weeding or adoption of post planting herbicides is essential. Preemergence herbicides, Pretilachlor (Sofit) can be applied with plant safner fenchlorim on to moist soil from 0-4 days after seeding to control emerging weeds. Pretilachlor would control all seed born weeds including grasses, sedges and broadleaves. The residual effect may long last for 2-3 weeks. Post emergent herbicides can be effectively used to control emerged weeds when the weeds are preferably at 2/3 leaf stage. An array of recommended herbicides is available as post emergent herbicides in rice cultivation. Depending on the type and stage of weed growth , appropriate herbicides should be selected. Propanil, Satunil, Butanil, Ronstar PI, Facet, Compro are some promising post emergence grass killers that can be applied from 8-12 days after seeding. Grasses which are failed to control by 8-12 days, will mature at later stages and their control needs strong herbicides. Whip super, Tiller gold and Rice star are promising herbicides that can be applied from 16-25 days after seeding to control mature grasses. Herbicides that can be adopted for overall weed control (control of annual grasses, sedges and broadleaves simultaneously) are known as oneshot herbicides. Some of these herbicides are mixtures of pre and post emergent herbicides and hence such mixtures require some wet conditions to ensure effective weed control. These herbicides include Lecspro, Profit, Nominee, Tiller gold and Solito. Usually these herbicides are applied from 6-12 days after planting. It is always better to apply when weeds are at 2-3 leaf stage. Periodic drying and wetting of soils during early stage of crop growth encourage rapid emergence of sedges and broadleaves. These weeds could be easily controlled with MCPA. Since young rice is sensitive to this herbicide, it is always recommended to apply MCPA when the age of the rice crop is between 2-3 weeks. Application of herbicides for upland crops is limited only for few crops. Almost all big onion growers are using pre emergence herbicides soon after onion seedlings are transplanted. There is no alternative to control - 182 -
early emerging weeds other than herbicides in big onion. Hence, it becomes compulsory to wet the fields for application of herbicides during dry periods. Pre emergent herbicides are also used to limited extent in some legume crops and potato cultivation. Keeping soil surface wet is essential for effective control of weeds in all these instances. The most common method of weed control in upland crops is manual weeding and periodic droughts pose less interference for this activity. (The details regarding recommended rates, time of application and field conditions are given in the Pesticide Recommendation Manual published by the Dept. of Agriculture)
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CHAPTER - 6
BEST CROP MANAGEMENT PRACTICES FOR FLOOD - 184 -
Effect of excess water on growth and yield of crops
epending on topography and rainfall patterns, lowland areas may be subjected to different water depths and to different durations of excess water. These areas may be tentatively divided as deep water areas, flood areas and submerged areas. When there is a water surplus in different degrees at different growth stages of rice, yield decreases in varied proportions. The decreasing of yields at partial submergence could be attributed to impaired tillering and decreased photosynthetic efficiency.
Flood conditions would cause reduction of oxygen in soil which subject root systems of up land crop plants to stress conditions and make susceptible to diseases. Generally soils have 1030% volume of air filled pores and this decrease when soil gets submerged. Excess soil moisture can cause a â&#x20AC;&#x2DC;physiological droughtâ&#x20AC;&#x2122; interfering water uptake by oxygen-deprived roots. Thus prolonged flooding cause a major stress to the plants that are grown under up land conditions.
Disease plays a major role in determining the survival of stressed plants. The roots of these plants are subjected to infections of fungi and bacteria that thrive in waterlogged conditions. (e.g Pythium and Phytophthora spp. and Pseudomonas spp.) Plant roots stressed by reduced oxygen exude more amino acids and ethanol that attract fungal spores. Nevertheless, flood conditions promote reproduction and dispersal of those pathogens.
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Flood-stressed plants show a range of symptoms including leaf chlorosis (yellowing), reduced leaf size and shoot growth, crown die-back, defoliation and eventual death of plants. In general high rainfall and high humidity would change the plant architecture and affect microclimate and thus impose high risks of infection by foliar pathogens. Moisture not only promotes new succulent and susceptible growth of the plants but also increases the growth of pathogens like many fungi, bacteria, nematodes and thus leads to disease epidemics.
Anthracnose of chilli
A critical factor in determining the survival of plants stressed by flood is whether they become invaded by diseases. Those weakened plants are prime target of pathogens. If a pathogen is successful in invading such plants, survival of those plants becomes less likely as the vigor and tolerance to diseases of those plants are reduced. In perennial crops (eg. Fruit crops) the battle to regain vigor and prevent attacks from diseases may continue for several years causing tree death over a period as long as 3-5 years. This will depend on many factors including plantâ&#x20AC;&#x2122;s tolerance to flooding, length of inundation, sediment levels etc.
Common rice pest under humid condition - Leaf roller
Common disease under humid condition - Shealth blight
Many farmers know the behavior of the location of their cultivation land with respect to flooding, duration of inundation etc. in high rainy situations, but farmers ignore this important factor when they are taking cultivation decision for the season. - 186 -
In Sri Lanka, we are not paying much attention to maintain natural drainage systems or drainage canals in irrigation systems. In such condition, water does not move freely in high rain situations and create land submergence or flood conditions. Floods can be categorized based on the size of the affected area. 1. River basin level 2. Tributary level 3. Tertiary level (mostly irrigation scheme level) 4. Tract drainage level (local drainage) River basin level and tributary level floods occur mainly due to formation of sand bars in the outflow locations. Some Farmer Organizationâ&#x20AC;&#x2122;s (FO) forward contribution of labor to remove these sand bars manually to get relieved of flood. Most often, government involves in clearing these barriers using machinery to control the floods at this level. Local authorities, FO and individual farmers sometimes involve to clear tertiary and tract level drainage blocking to drain out floods.
Green leaves for flood vulnerable area
Paddy lands that are located close to drainage system are susceptible to submergence quickly. In the early stage, Paddy crop is not much affected if it is submerged for few days and recovers after water is drained out. On the otherhand all non Paddy crops will get damage from the flood water. When you assess the climatic condition in the planning stage, and if your field is located in flood vulnerable area and your assessment is towards high rain conditions, avoid crops which are not water loving. Select crops like green leaves.
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Rice crop management practices to cope with flood Crop establishment
Sowing should be done soon after the receipt of pre-monsoon showers. Successful crop establishment is the most important factor affecting productivity in flood-prone environments. Successful crop establishment is highly dependent on the rainfall pattern, the internal and surface drainage characteristics of the land and socioeconomic conditions of farmers. Using appropriate cultivars and timely crop establishment through either direct seeding or transplanting are essential operations for improving crop productivity. If crop establishment problems can be overcome, flood prone environments have high potential for increased rice productivity.
a. Direct seeding If direct seeding is to be followed, timely seeding at proper depths and uniform germination are to be assured for even stand establishment prior to flood water accumulation. Sowing should be done soon after the receipt of pre-monsoon showers.
When light showers received land preparation should be done allowing sowing in relatively dry soil
Optimum seedling density is 400600 seeds per sq.m. for excess water condition
b. Transplanting In transplanting, special attention has to be paid to nursery and seedling management in order to produce, healthy, tall (high vigor) seedlings, which can anchor firmly and adequately withstand submergence. Transplanting is risky if water accumulates immediately after planting as it would impose excess water stress on the young seedling, resulting - 188 -
in greater plant mortality and reduced tillering. However, risk can be reduced by transplanting taller, relatively older seedlings. Floods occurring at planting time and late onset of monsoon may delay transplanting. Under such conditions, bunch planting of overaged seedlings of long duration rice cultivars is restored to mitigate the harmful effects of excess water. Seedlings from the fertilized nursery having a well developed root system, higher dry weights, and greater concentration in the plant tissue at the time of planting should be used to withstand the effects of flood.
Nursery management Nursery management practices, especially seeding density and fertilizer application, can alter the quality of seed beds, which directly affect the growth and yield of transplanted rice. Higher seeding density in the seed bed delayed the flowering and maturity of transplanted rice.
Seedling management It is advisable to keep the seedlings in fresh running water for 24-36 hours and to detop two third of the leaf length (to reduce transpiration) before transplanting.
Root pruning before transplanting, leaving 2 to 5cm length for the 18 and 25 day old seedlings, is recommended to give higher plant height up to 40 days after transplanting and more tillers, leaf area index, shoot biomass, and grain yield because of more panicles than the uncut roots. However, too much pruning of roots, leaving 1cm before transplanting, significantly reduce plant height and shoot and root biomass.
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Double transplanting of seedlings is a traditional system in flood prone areas. Initially, 3-4 weeks old seedlings are transplanted leaving them to grow for 4 weeks. Then the 4 weeks old transplanted crop is uprooted and again replanted.
In flood prone areas, sediments contain appreciable amounts of organic matter and N, P, K, S, Ca, Mg, Fe, Mn, Zn and B. Nitrogen is the only possible limiting nutrient for rice production in flood prone areas. Fertilizer recommendations should be based on regular sediment and soil tests to avoid over application of fertilizer in flood prone areas. Several N fertilizer management techniques, such as the use of leaf color chart, urea super granules and slow-release fertilizers, appears to be promising for the flood prone ecosystem.
Weed management Weeds are undoubtedly a serious problem in rice grown in the flood prone environment. Aquatic weeds would proliferate and compete with flood prone rice system. Floating weeds may intrude in to the rice field along with flood water and may cause serious problems. Wild rice species having tolerance for flooding and elongation ability are a serious threat to this system. The possible current practice of weed control in dry-sown rice is hand weeding, which is laborious and costly. Herbicide is an alternative to hand weeding before flooding. To control floating weeds, fencing around the water inlets is a very popular method as no other cost effective weed control method is available to control them.
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Guidelines for common water source users Fact Floods occur due to improper drainage system.
Objective System operators and farmers must pay equal attention to maintain drainage lines as well as irrigation canals.
Clear local level natural drainage lines
When you clean irrigation canals before starting of the cultivation season, clean the drainage canals as well. Some people put plant debris, crop residues into drainage lines which block the drainage flow. Re-use of drainage water is a good habit in normal or below normal weather conditions. When people make temporary diversion structures, those must be removed after the job is completed. Most people neglect this removal, and under such circumstances with high rains smooth water flow is interrupted at these places creating floods. So remove these temporary diversion structures before rains.
Drain out remaining water immediately Paddy:
After flood and bad weather condition, most crops may fallen down to ground. If the crop is in late maturing (harvesting) stage, we can do only drain out the field completely and allow crop to dry or remove crop from the field. If the crop is in the early bearing stage, drain out the field completely for few days. After that supply two or three irrigations just enough to saturate the soil. Don’t keep standing water. If the crop is in a early stage than above two stages, crop will recover; so practice normal irrigation after floods are over. If the crop get drifted away by floods and sufficient time left in the season, re-sow the field. If the damage is in small part - 191 -
and the crop is at early growing stage, fill the vacant patches by transplanting with the seedlings removed by thinning out of some dense places.
After flood and bad weather condition, most crops may fallen down to ground. Support crops to stand by collecting soil to base of the plant.
Identify flood vulnerable area and plant only selected crops
Farmers have a good understanding on their field conditions and know the areas that become submerge when floods occur in the fields located at flood planes. In most of the areas, floods do not long last for more than two or three days. When you select the crop, consider this factor also and choose water loving crops e.g. leafy vegetables (“Kohila”, “Kankun”) and climbing/ creeping type vegetables like Bitter gourd, Wing bean, Snake gourd and Luffa (Fence gourd). The special feature of these vegetables is that their vines can be trained on a strong horizontal trellis about 2m height above ground level. If flood water remains not more than 3 days, this vegetables would not have any serious damage from flood. Non LHG soil is good for raising this kind of plants.
Use raised bed cultivation
If your land submerges with heavy rains and water would not stand more than 15cm (6 inches) depth, you can prepare land in raised bed or ridge and furrow method. Don’t use basin cultivation or seed drilling on normal ground in these locations.
Guidelines for rain-fed farmers
Fact Flood and heavy rain will damage the crop.
Objective Restoration of cultivation to get some harvest.
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Drain out the remaining water immediately
Support to stand the crop by gathering soil to base of plant
Restore damage bunds and water saving structures
After flood and bad weather condition most crops may fallen down to ground. Drain out the remaining water immediately. Plants in some areas may be washed off. If the cultivation is in early stage, uproot plants from unaffected densely populated places and fill the gaps with them.
Some crops like Maize, Chilli may fall down to ground. Collect soil to the base of the plants to support them standing.
To capture rain water and improve infiltration most rainfed farmers build bunds to create small basins. When heavy rains/ floods occur bring back to open these bunds to drain out excess water. After heavy rains/ floods, repair all damaged bunds to bring back to normal functioning.
Cropping systems and strategies for Flood prone areas Establishment of sorjan system in low lying areas for growing crops Another way to overcome submergence or ill drained conditions of low lying areas, is the development of land itself in order to escape from flash floods and submergence. Such a system called â&#x20AC;&#x2DC;Sorjan systemâ&#x20AC;&#x2122; is available and it is presently adopted in low lying areas in Indonesia Vietnam and Thailand. The principal of Sorjan system is to make alternate ditches and dikes on the land. Depending on the severity of flood, 3-5 feet deep ditches are dug and the soil is
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heaped on the adjacent dikes so that the height of dikes is couple of feet higher than normal soil level. The ditch may be capable of holding additional water equivalent to the volume of soil removed to make the ditch. Thus during flooding, water level does not go over the dike. Width of the ditches and dikes are the same and may be 3-5 feet wide depending on the severity of the expected floods, soil type and the crop to be cultivated. Ditches and dikes should be made during the dry period and dikes must be made strong enough to tolerate the floods without getting damage. Care must be taken to have top soil on the top of the dike. Not only rice but any other suitable crops, even a perennial like cinnamon and coconut can be grown on dikes which do not go under submergence during flooding. Water plants like lotus can be grown in ditches so that both dikes and ditches can be successfully utilized and productivity or the production per unit land area can be kept high without wasting the land. Sorjan system may be successfully adopted in slightly and moderately flood prone areas through out the year. However, Sorjan system can be adopted in severely flood prone ill drained areas, only when the flood is receded, with short age annuals like rice varieties that mature within 80 days because severely flood prone areas are submerged most of the time of the year with few inches of water and during flooding flood level may be too high even to tolerate with dikes. The major problem with Sorjan system is that land work is very expensive so that individual farmers may not be able to afford this. Thus the government support is necessary at the initial land work for the construction of ditches and dikes. Once the initial land work is completed, system can be maintained by farmers. Technology of the Sorjan system is already recommended by the Dept. of Agriculture and available for farmers. If it is coupled with suitable crop varieties, particularly rice varieties, most of the low lying areas which are now remaining unproductive can be successfully made into productive lands.
Flood prone areas during Maha Season: use of photoperiod sensitive “mawee” varieties There are low lying paddy fields, in the Puttlem, Kurunagala, Gampaha, Colombo, Kaluthara, Galle and Mathara districts, that undergo flooding for 1 -2 weeks duration up to 1 -3 feet depth of water during NovemberDecember heavy rains. Often, land preparation also can not be done in low lying paddy fields in October due to continuous rains. Therefore crop has to be established before September of a given year. However, if normal photo-period non-sensitive paddy varieties are cultivated in September, they will flower in November/ December during rainy days and the crop will be damaged. In order to get away from this problem, photoperiod sensitive “mawee” varieties can be adopted. Regardless of the time of sowing, (between June-September), they will flower only in January after rain and will be ready to harvest in dry period during February. These - 194 -
varieties can withstand flooding during November-December, when they are at maximum tillering stage without reasonable crop damages.
Flood prone area-during Yala season: use of submergence tolerant medium maturity varieties
Low lying paddy fields in Kaluthara, Galle and Mathara districts that comes under flood planes of Kalu ganga, Benthara ganga and Gin ganga undergoes flooding during May-June of a given year. If normal rice varieties are cultivated in these areas, they cannot withstand submergence. Therefore submergence tolerant, non-photoperiod sensitive varieties are needed for these eco-systems. For example Bg 741 is a submergence tolerant 4 month variety that is well adapted to these eco-systems.
Pest and disease management Pest management is difficult in flood prone rice system. Natural biological control is the core of pest management in the system. The use of pesticide in the system poses additional danger to water body pollution. Among the diseases, sheath blight, and blast are the most important diseases which cause considerable yield loss. Use of resistant varieties and disease free breeder seeds, avoiding excess use of nitrogen fertilizer, keeping standing water in the field, and using effective fungicides are the possible measures to combat the predominant diseases.
Diseases occur frequently in excessive rainfall or flooded conditions Under floods, generally, population of aerobic pathogens are low while those of the anaerobic pathogens are high. Extended floods can kill most of the plants while some plants like papaya is extremely susceptible for water logged conditions.
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1. Root and stem rot and aerial (foliage) blight and damping off seedlings caused by Phytophthora spp. and Pythium spp. Symptoms The symptoms are damping off of seedlings, wilting, leaf yellowing, leaf shedding, die-back of perennials and eventual death of plants. The root system often become blackened and rotten.
Hosts Vegetables, other filed crops, potato and fruit crops. Papaw and Durian are highly sensitive to water logged conditions and predispose to infection while plants at all stages are subjected to infection. The nursery plants and seedlings are highly susceptible.
Epidemiology Phytophthora spp. and Pythium spp. commonly known as water mold fungi live mainly in soils ideally suited for waterlogged conditions. Infective spores are dispersed in surface water and also spread through soil and survival had been known even for about 6 months. High humidity, poor drainage and close spacing favour infection and disease development.
Management strategies Cultural control
1. Facilitate drainage. 2. Use correct spacing and remove excessive shoots and branches (mainly of fruit trees). 3. Remove infected plants, branches and destroy them. 4. Burn or solarize soil of nursery beds before planting. 5. Crop rotation with non susceptible varieties.
Chemical control Soil and seed treatment
Use recommended fungicides as seed treatment (Captan 50% or 80% WP, Thiram 80% WP, Chlorothalomil 75% WP or 500 g/l SC) or as spot application to the soil, Flutolanil for nursery beds 3 days before seed sowing, Dazomet 14 days before seed sowing and loosen the soil 4-8 days after treatment. This should be done at regular interval until traces of Dazomet removed.
Biological control Trichoderma spp. is used as soil application. - 196 -
2. Shoestring root-rot â&#x20AC;&#x201C; caused by
Symptoms are root-rot resulting in slow decline or crown canker which girdles the trunk causing quick death of the infested plants. Loss of foliage and twig dieback are other symptoms. Thus fungus produces white mycelium and black shoestring like rhizomorphs that invade woody parts and also penetrate the surrounding soil. Honey coloured mushroom like structures are produced at the base of the trunk.
Epidemiology Root-rot and crown-rot would induce by flooding or high level of moisture in the soil. The fungus survive in diseased tissues, spread through soil, root contact and spores by wind.
Host Avocado, Citrus, Mango, Rambutan, Grapes and other perennial woody plants.
Management strategies Cultural control
1. Facilitate drainage. 2. Remove infected parts of the crown and roots. 3. Remove infected soil in the root zone and replace with sand.
Chemical control Drench soil with recommended fungicides at the appearance of symptoms or apply to the crown (Copper 50% WP, Copper 37.5% WG) after removing the infected tissues.
3. Anthracnose â&#x20AC;&#x201C; caused by Colletotrichum (Gloeosproium) spp. Symptoms
This disease causes symptoms in all above ground parts of the plants including foliage, stems, flowers, fruits and seeds. Symptoms appear as dark coloured spots or sunken lesions, twig or branch die-back, fruit rot, fruits and flower drop.
Fruits, vegetables and other field crops.
The fungus develops fast in wet weather and infects young tissues, with spores spread by rain splash or winds. - 197 -
Management Strategies Cultural Control 1. 2. 3. 4. 5. 6.
Decrease humidity and minimize watering. Use disease – free seeds. Use of resistant varieties. Use correct spacing. Remove infected parts and destroy them. Destroy weed hosts.
Chemical control Management is most effective when fungicides are applied at the apperarnce of the symptoms. Use recommended fungicides. (Chlorothalonil 500g/l or 75% WP, Mancozeb 80% WP, 75% WG or 480g/l SC, Maneb 80% WP, Thiophanate-methyl 70% WP or 500g/l SC, Thizilazole 400g/l EC, Pyraclostrobin 250g/l EC).
4. Leaf spots – Alternaria spp., Cercospora spp. and other fungal spp.
These are most common diseases of many plants. Some of the diseases caused by Alternaria include early blight of potato and tomato, blight of carrot and capsicum purple blotch of onion etc.
Symptoms Leaf spots are generally dark brown to black, often numerous enlarging and usually developing in concentric rings. All above ground parts of the plants are invaded including leaves, stems, fruits or grains and flowers etc. Leaf yellowing, falling, twig blight are other symptoms.
Hosts Vegetables, fruits, rice and other field crops.
The fungus develops fast in wet weather and spread the disease rapidly in young tissues.
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Decrease humidity Remove and destroy infected plant parts Use correct spacing Use disease free seeds Use resistant varieties Destroy weed hosts
5. Downy Mildew caused by Peranospora spp., Pseudoperonospora spp., Peranosclerospora spp., and Plasmopara spp. Symptoms
Initially small, pale yellow, irregular spots appear on the upper surface of the leaves and a downy growth of the spores of the fungus appears on the underside of the spots. Later the infected areas are killed and turn brown while the spores become dark grey. The spots often enlarge, coalesce to form large dead areas on the leaf and result in defoliation. This fungus infects all above ground parts including leaves, flowers, fruits, twigs; showing distortion, decay and discolouration resulting in low quality fruits and loss of yield.
Hosts Vegetables, fruits, other field crops and cereals.
Epidemiology Infection occurs when there is water on the surface of the plant tissues and with high humidity. However, mildew spores disseminate fast in dry weather with winds and may develop into epidemic proportions if no control measures are undertaken. Fungus spread through seed or planting materials as well.
Management is most effective when fungicides are applied to the young flush, inflorescences and to young fruits. Use recommended fungicides (Captan 50% WP, 80% WP or 480g/l sc; copper 50% WP or 37.5% WP; Mancozeb 80% WP or 75% WP; Propinets 56% + Oxadixyl 10% WP; Propineb 70% WP, Valiphenal 6% + Mancozeb 60% WG; Propomocarb 607g/l SL; Pyraclostrobin 250g/l EC) select more than one fungicide and use alternately.
6. Rust caused by Puccinia spp. and Uromyces spp. Symptoms
Rust fungi infect almost all above ground parts. It usually appears first on the leaves in the form of light-coloured, small raised, blister like spots. The epidermis of the spots erupts and exposes orange or brown powder like uredospores. When lesions expand, defoliation, distortion of flowers and fruits and eventually death of weakened plant may occur. Rust
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Vegetables, fruits, other field crops and cereals.
Epidemiology Disease spread through wind blown spores, although insects, rain and animals also contribute the spread. The disease spread fast in dry windy weather.
Management strategies Cultural methods 1. 2. 3. 4.
Use disease â&#x20AC;&#x201C; free seed and planting materials. Seed treatment with recommended fungicides. Remove infected plant parts and destroy. Use resistant varieties.
Chemical control Management is most effective when fungicides are applied at the initial stages of the infection. Use recommended fungicides.(Bitertanol 300g/l EC, Tebuconazole 250g/l EC, Mancozeb 80% WP or 75% WG, Sulphur 80% WP or WG, Chlorothalonil 500g/l SC or 75% WP, Copper 50% WP or 37.5 WG)
7. Baterial wilt â&#x20AC;&#x201C; caused by Ralstonia solanacearun Symptoms First symptom is wilting of growing tips or some leaves and later the whole plant wilts and dies rapidly. Vascular tissues of stem, roots and tubers become brown and packed with bacteria which ooze out if the cut end of the stem is immersed in water and increase the turbity of water showing milky appearance. In some plants excessive adventitious roots may form.
Wide range of hosts (about 200 plant spp.) including solanaceous crops (potato, tomato, capsicum, brinjal, tobacco) banana, some legumes, ginger, mulberry, many weeds etc. However, banana strain is not reported in Sri Lanka.
Epidemiology Bacteria survives in soil and spread through the infected soil, water and planting material such as rhizomes and tubers. Root nematodes also enhance the spread and infection of this disease. - 200 -
Flooding would reduce the population of bacterial as it creates anaerobic condition in the soil. However, soil moisture at and below optimum levels favours multiplication of the bacteria rapidly. Therefore this disease is more severe in the wet zone. In high altitudes when temperature is below 15oC, bacterial survival is minimum and same would happen when the temperature increases above 43oC. Therefore, bacterial wilt incidences are low in upcountry where temperature goes below 15oC and low country dry zone areas where high temperatures prevail in certain periods of the year (eg. Jaffna and Kalpitiya).
Management strategies 1. Facilitation of drainage. 2. Flooding soil for about one week. 3. Drying up of soil and ploughing to expose bacteria to high temperature. 4. Use resistant varieties â&#x20AC;&#x201C; This is the most effective management strategy. Tomato and Brinjal varieties recommended during the past decade are moderately resistant to bacterial wilt. 5. Use disease-free planting materials. 6. Crop rotation with resistant crops or fallowing for about 2-3 years.
8. Soft-rot â&#x20AC;&#x201C; caused by Erwinia carotovora and other Erwinia spp. and some secondary bacteria (eg. Pseudomonas, Bacillus Clostridium spp.) After flooding or and drought conditions followed by rains, Erwinia and other bacterial pathogens mentioned may invade the damaged plant tissues and cause soft rots. Foul smell would be resulted in due to volatile substances released during the disintegration of plant tissues.
Symptoms Soft-rot symptoms begin as small water-soaked lesions, which enlarge rapidly. The affected area becomes soft and mushy while the surface becomes discoloured and depressed. Outer surface may remain intact while entire contents inside rot and turn into a turbid liquid. Later cracks would develop and slimy mass exude. A whole fruit or tuber or sometimes the plants (eg. Banana) may convert into soft, watery decayed mass within a few days. Basal part of stems of the potato may become blackened (black leg) and the whole plant may wilt and die. Soft rot
Hosts Vegetables, fruits, onion and potato etc.
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These bacteria survive in soil, water, infected plant tissues, contaminated equipment and spread through the above. They enter primarily through wounds or damaged tissues. The bacteria produce pectolytic enzymes that breakdown pectic substances of middle lamella and bring about maceration of the tissues.
Management strategies 1. 2. 3. 4. 5. 6.
Avoid flooding, drought or any other stress condition in the field. Avoid wounding in the field and during storage. Facilitate drainage. Use correct spacing. Crop rotation with cereals or other non-susceptible hosts. Good sanitation. Discard all infected plant parts.
9. Black-rot caused by Xanthomonas Camperstis pv. Campestris Symptoms This disease occurs in above ground parts of plants of any age. This cause extensive field losses from seedling damaging-off and decay of mature heads. Infected seedlings show stunted growth. On the leaves first symptoms usually appear as Vshaped chlorotic blotches at the margins of leaves. These blotches progress towards the midrib of the leaf and veins may become black. The affected area turns brown and dry. Infected leaves may fall off prematurely. In cross sections of the stem and the stalks show blackening of vascular tissues Black rot and yellow slime droplets of bacteria. Cabbage and cauliflower heads would be invaded and discoloured as are the fleshy roots of radish. Infected areas are subsequently invaded by soft-rotting bacteria which destroy the tissues and a repulsive odour may be resulted in.
Hosts All members of crucifer family.
Epidemiology This bacteria survive in infected plant debris, soil and in the seed. The bacteria often ooze out from the infected parts of the plants and spread by rain splashes, wind or agricultural tools. Infection develops rapidly in warm wet weather. The disease is spread through infected seed, soil, water and plants.
Control strategies 1. 2. 3. 4. - 202 -
Use disease-free seeds. Seed treatment with hot water (50oc for 30 minutes). Destroy infected debris. Minimize damages to plant tissues.
10. Bacterial Canker of Citrus â&#x20AC;&#x201C; Xanthomonas
campestris pv. citri syn. X. axenopodis
Symptoms The disease symptoms occur in any above ground part of the plant including leaves, fruits, twigs and branches. First symptoms are small, slightly raised, round, light green spots. Later they become grayish white, rupture and appear corky and raised with brown centres. The margins of the lesions are surrounded by a yellow halo. Severe infections of leaves, twigs and branches would weaken the trees while infected fruits appear scabbed and deformed.
Epidemiology Bacteria survive in plant parts, and not in soil. Bacteria ooze out of the lesions in rainy weather, splash onto young tissues or spread through wind to other plants. This disease is more common in areas of wet and high temperature (low and mid country wet and intermediate zones).
Control 1. 2. 3. 4. 5. 6.
Use disease-free plants. Use resistant varieties. Pruning and destroy of infected plant parts. Use wind breaks. Protect young plants in the nurseries from rain. Apply copper fungicides.
Pest management strategies for flood Floods results in standing water in the fields and this favours the development of pests like Whorl maggot. Continuous submerged conditions in the field favour rice brown planthopper. Army worm and cut worm damage is severe in periods of drought followed by heavy rains. Gall-midge incidence is high in cloudy or rainy weather. High humidity and shady conditions favours development of rice leaf folders. Rice bugs prefer warm weather, overcast skies, and frequent drizzles.
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1. Rice whorl maggot (Hydrellia philippina) Nature of damage The larvae rasp plant tissues with their hardened mouth hooks. They eat the tissue of unopened leaves leading to white or transparent patches near edges after leaves unfold.
Rice whorl maggot
Draining the water at intervals during the first 30 days of transplanting, can reduce ovi-position by the adults. However, this can increase the incidence of weeds. Use direct seeding rather than transplanting. In endemic areas incorporate granular insecticide at first harrowing to soil (Carbofuran 3% GR and Diazinion 5% GR). Use foliar insecticides (Diazinon 500g/l EC or Phenthoate 500g/l EC) 1-2 weeks after transplanting.
2. Rice gall midge (Orseola Oryzae) Nature of damage Gall-midge becomes abundant in rainy weather in irrigated rice. The infested tillers developed into silvery white hollow tubes that do not bear panicles.
Management Remove weeds and wild rices in rice fields. Plant resistant varieties (Bg304, Bg57, Bg358, Bg360). Treat nursery with recommended insecticides (Carbofuran 3% GR, or Diazinon 5% GR or Benfuracarb 3% GR or Fipronil 0.3% GR). Broadcast granules on to wet mud or 1cm of standing water 2 weeks after transplanting or 2-3 weeks after broadcasting. Apply insecticide when the damage exceeds, 5% galls. Rice gall midge
3. Leaf folder (Cnaphalocrocis medinalis) Nature of damage The larvae feed inside a protective chamber made by folding the leaf margins and attaching it by silken threads. Larval feeding cause longitudinal white transparent streaks.
Management Use recommended amount of fertilizer in split application. Control weeds - 204 -
in and around the fields. Conserve predators and Parasites. Use recommended insecticide Chorpyrifos 200g/l and 400g/l EC or Fenthion 500g/l EC, Tebufenozide 200g/l SC, Fipronil 50g/l SC, Methoxyfenozide 240g/l SC, Chlorfluazuron 50g/l EC, Azadirachtin 10g/l EC, Chromafenozide 50g/1 SC, NoÂŹvaluron 100g/1 EC and Acephate 75% SP. Apply insecticide when 25% of the leaves show more than 50% leaf damage. Follow the label instruction when using insecticide.
4. Rice brown planthopper (BPH) (Nilaparvata lugens) Nature of damage The rice plant is more sensitive to attack at the late vegetative stage or in the reproductive stage. Feeding by the nymphs and adult insects results in drying and browning of leaves and patches of hopper burn plants are observed.
Use resistant varieties (Bg300, Bg305 Bg357, Bg358, Bg359, Bg360, planthopper Bg379-2, Bg403, Bg403, At405). Conserve the predators and parasites as they attack all the stages of the pest. Draining the fields help to reduce BPH multiplication. Use recommended insecticides. (Buprofezin 10% WP, Novaluron 100g/l EC, Imidacloprid 200g/l, SL Fipronil 50g/ l SC, Acetamiprid 20% SP, Thiamethoxam 25% WG, Imidacloprid 70% WG, Imidacloprid 200g/l OD, Ethiprole 100g/l SC, Thiocyclam (hydrogen oxalate) 4% GR, Thiocyclam 50% SP, Etofenprox 100g/l EC, Carbosulfan 200g/l SC, Carbofuran 3% GR, Fenobucarb 500g/l EC). Apply insecticide only when number of BPH (adults+nymphs) exceed 5-8/hill tillering and 8-10/hill at maturity.
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CHAPTER - 7
MANAGEMENT OF LAND AND WATER RESOURCES TO REDUCE EFFECTS OF DROUGHT AND FLOOD AT VILLAGE LEVEL - 206 -
wo major natural calamities which hamper the yield of the crops grown by the villagers are occurrence of floods with heavy rains and drought with prolonged dry spells. This eventually reduces their major income leading to poverty. Therefore, from ancient civilizations at village level people were vigilant about the occurrences of drought or floods, and different strategies were adopted to mitigate the effects. Effect of drought may be due to some of the problems associate with following; Inadequate rainfall or water source is not supplying enough water to meet the crop water requirement. Inappropriate selection of land, crop and cropping system for agriculture. Poor supply of water to water bodies (lakes, reservoirs etc.). Inappropriate time of planting and variety selection. Problem in soil and moisture conservation. Even in the past villagers have identified the importance of available water resources in a village such as village tanks, canals and natural water ways, drainages etc. in managing floods and droughts. Also they adopted several crops/ cropping systems and land management techniques to reduce the effects of floods and drought. This chapter will discuss the different land and water resources management strategies adopted by farmers and also possible other methods which are available to reduce the effects of floods and drought at village level. Out of so many factors which can be considered as important in reducing the effects of floods and drought at village level, management of watersheds is considered as one of the most important aspect.
Watershed management A watershed is an extent of land where water from rain drains downhill into a body of water, such as a river, lake, reservoir, estuary or wetland. The drainage basin includes both the streams and rivers that convey the water as well as the land surfaces from where water drains into those channels, and is separated from adjacent basins by a drainage divide. In a village they are mostly preserved forest blocks or homesteads just above the water bodies.
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Watershed management can be defined as the planning and carrying out of actions, legal requirements and protective measures taken by agencies and citizens to preserve and enhance the natural resources of a drainage basin for the production and protection of water supplies and water-based resources. In other words watershed management will ensure adequate supply of water to village tanks or other water bodies during rainy seasons. Further, this will also emphasize the preservation and conservation of water received from rainfall to meet the demand from agriculture and domestic affairs of the village community in sustainable manner. In addition, adequate measures should be taken to prevent the erosion of soil to minimize the siltation of reservoirs. Some of the main activities which are important in watershed management in reducing the effects of drought and floods at village level are discussed below.
1. Conservation of existing forest cover
Population is increasing steadily in the world creating higher demand for food. To provide enough food to meet the demand of increasing population, one of the strategies adopted by planners is to increase the area under cultivation.
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Usually forest cover intercept rainfall
That means opening up of more unused lands for agriculture. Most often, these lands are the conserved forest in a village ecosystem. Continuous reduction of those forest reserves will reduce the area of the watershed at village level. Usually forest cover is intercepting rainfall & retains part of the rainfall and allows the balance to move away as runoff to pass through to village tanks with non erosive velocities. Leaf litter mulch in forest floor improves the rain water infiltration which reduces the runoff flow resulting reduction of soil erosion and increases the base flow when there is no rainfall. Therefore forest cover is playing an important role in controlling runoff which eventually helps to reduce the occurrence of floods with prolonged rains.
2. Development of dense vegetation in home gardens After a heavy rainfall, a unit of land which is kept bare (no trees) or maintained with few trees, has a tendency to observe more runoff than a land which has more trees. More trees in a unit area will intercept higher percentage of water from rainfall and will reduce the rate and the amount of runoff. Perennial fruit crops are ideal in increasing plant density since they develop a fairly dense canopy cover and also give a steady yield to support the rural income. Therefore, it is important to maintain a fairly dense vegetation in a home garden to reduce the runoff as otherwise which can create flood conditions in low laying areas in the village.
3. Decrease deforestation
Natural forest in a village is always under threat from encroachers who clear the forest for Chena cultivation and for other uses. - 209 -
Similarly illegal cutting of trees for fire wood or timber is also very common in villages. Besides, occurrence of fire during dry period is also a common problem. All these factors contribute to decrease the area under forest in a village catchment. Cleared forest land will create more runoff compared to a well managed forest land after a rain, establishing favorable condition to create floods. Threfore it is very important to take necessary steps to minimize or prevent deforestation in a village. This could be possible by imposing strict legislation with the community support in the village level.
4. Aforestation (plantation forestry) Plantation forestry plays an important role directly by conservation of watersheds and indirectly by providing the timber and fuel wood requirement, thereby reducing the threats to the natural virgin forests. In plantation forestry, selection of suitable tree species emphazising more on ecological benefits must be encouraged. Tree species like Pinus which tap the ground water resulting massive depletion of ground water must be avoided.
5. Promote agroforestry
According to International Council for Research in Agroforestry (ICRAF) 1993, agroforestry is a collective name for land use systems and practices in which woody perennials are deliberately integrated with crops and/ - 210 -
or animals on the same land management unit. The integration can be either in a spatial mixture or in temporal sequence. Normally there are both ecological and economic interactions between woody and nonwoody components in agroforestry systems, where trees or shrubs are intentionally used within agricultural systems, or non-timber forest products are cultured in forest settings. Knowledge on selection of appropriate species followed by good management of trees and crops are needed to optimize the production and realize positive effects within the system, while minimizing negative competitive effects. Agroforestry systems can be advantageous over conventional agricultural and forest production methods through increased productivity, economic benefits, social outcomes and the ecological goods and services provided. Biodiversity in agroforestry systems is typically higher than that in conventional agricultural systems. Agroforestry incorporates at least several plant species into a given land area and creates a more complex habitat that can support a wider variety of birds, insects, and other animals. Agroforestry also has the potential to help reduce climate change since trees take up and store carbon at a faster rate than crop plants. Also these trees must have the ability to establish dense canopies in relatively short period of time. This will increase the strength of the watershed in the village which eventually helps to increase the water availability in the dry period as well as to reduce the flood hazard in the rainy season.
6. Increase the availability of domestic energy sources People intentionally or unintentionally cut trees or branches in the forest trees to meet their domestic fire wood requirement. The small scale industries like bakeries, bricks and tile industries etc. also try to rely on forest which is in their close vicinity for their energy requirement. All these activities will - 211 -
disturb the forest resulting a threat to watershed. Paddy is the most predominant crop grown in most of the villages in Sri Lanka. During the process of converting paddy to rice paddy, husk is collected as a waste. These paddy husks can be used as an alternative energy source to reduce the use of fire wood in cottage industries and houses. Also coconut waste and waste from other cultivated trees can be used to meet the domestic energy requirement. This will reduce the dependency of village people for fire wood from the conserved forest.
7. Increase awareness Most often, people practice various activities when they have convinced about the importance or the usefulness about a practice or an activity. Therefore, it is very important to make the people aware about the importance of watershed management and the consequences of mismanagement. If they are fully convinced about the factors related to occurrence of floods and drought due to mismanagement of their watershed, definitely they will take the leadership to manage the watershed properly since they love their village and the ecosystem. Awareness can be done through TV progremmes, audio presentations using radio, distribution of leaflets, posting of banners etc. Also informative dramas and quiz contests aiming youths and children are also some of the possible activities to increase the awareness of watershed management in order to reduce the effect of flood and drought occurrence.
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Land use planning Land-use planning is the systematic assessment of land and water potential, alternatives for land use and economic and social conditions in order to select and adopt the best land-use options. Its purpose is to select and put into practice those land uses that will best meet the needs of the people while safeguarding resources for the future. In other words planned land use in a village will utilize the available land appropriately and efficiently taking consideration of available water, crop suitability, and land suitability avoiding possible threats from droughts or floods with natural calamities.
1. Selection of appropriate crops to suit the land class Generally, topography of the village is varied depending on the area where the village is located. For example, if a particular village is located in the up country, often, steep slopes can be observed, whereas in the low county, terrain is slightly undulating or flat. Apart from the area where the village is located, different topographical classes can also be observed even within the village itself. Hence, land and land management decisions should be taken based on careful examination about the individual situation. Soil depth and drainage characteristics of the land must also be taken into account when formulating possible cropping plans and land management scenarios to reduce flood damages. Deep rooted perennial crops like Jack, Mango etc. need fairly deep soil with good root aeration. This group of crops must be established in the uppermost area in the land terrain. Conversely, shallow rooted fruits and vegetables must be accommodated in the middle part of the terrain. Lowest part of the terrain having shallow water table along with shallow soil depth is more suitable for paddy and the crops which can withstand occasional flood conditions. Even in indigenous agricultural practices, upper portion of the land catena has never been cleared for agricultural practices and kept as natural forest lands for soil conservation as well as ground water recharge.
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Kandyan forest garden
In middle portion of the catena, plantation crops like rubber, well managed tea plantations and multi storied homegardens such as kandyan forest gardens, which mimics natural forest can also be practiced. These systems help to intercept rainwater due to dense canopy and
to reduce the runoff flow by temporary storing the rain water through deep leaf litter layer which act as a sponge. This will delay the time of concentration of storm water to the water bodies such as rivers and village tanks, preventing the occurrence of flash floods. Roots and stems of the trees act as natural barriers to the runoff water flow leading to the ground water recharge. This recharged ground water plays an important role, especially, during the drought by forming a base flow to the rivers and other water bodies ensuring the availability of water during the drought. This kind of crop arrangement is favorable even to escape drought conditions which can be experienced within a season. However, other land management practices also must be practiced simultaneously to achieve long term soil and water conservation to reduce the effects from flood and droughts.
2. Promotion of proper land management practices
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Selection of crops based on topography and drainage class will only make the conditions favorable in reducing the effects when drought or flood occurs in a village. Adaptation of proper soil/ land conservation and water management practices are also very important and vital in achieving the task. Some of the important activities are given below;
a. Contour bunding This is a very important practice to control runoff leading to lowering of soil erosion in a steep slope area. In this process, elevated bunds are constructed along the contours either by soil or stones against the gradient at regular intervals in the catena. The interval between two bunds will be decided depending on the slope. Higher interval between contours will be maintained with slight slopes and lower intervals with steep slopes to reduce the energy of the runoff flow. Different types of contour bunding can be observed depending on the concern for soil conservation.
Contour bunding with a drain just below
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Contour bunding with grass strip just above
These drains should be constructed as lock and spill drains to maximize the ground water recharge and to drain the runoff water under non-erosive rate. All these drains should be directed to the terraced and stone paved leader drains to discharge runoff water under safe velocities. Contour drain with locks and spills
b. Contour terraces Construction of contour terraces against the gradient of the land considerably reduces the velocity of runoff flow facilitating more rain water to infiltrate. This will increase the ground water resources which can be tapped during the drought. In addition to that, contour terracing reduces the soil erosion by re-depositing the eroded soil and breaking the speed of runoff flow. Contour terraces
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c. Vegetative barriers
Sloping Agricultural Land Technology (SALT) Closely planted double rows of suitable hedgerow tree species at close interval reduces the speed of runoff flow and trap the soil particles in steeply sloping lands. Deep, well developed root system binds soil particles together thereby reducing the soil erosion. In addition to that, pruning of the hedgerows act as mulch which will reduces the flash erosion. Calliandra and Adhatoda vasica plants
All these methods will reduce the energy in the runoff flow and thereby reduce the transportation of soil to lower area. That will reduce the opportunity of unnecessary filling of sand and clay in the down stream which block the runoff flow by rains. Hence reduce the effect of floods to the village.
3. Improve natural drainage Natural drainage ways can be found in villages connecting drainage water from many small segments of lands (micro catchments). This drainage ways finally link in to a fairly big drainage way which is usually a small stream serving in numerous ways to villages. In some instances these streams will either link to a river or a reservoir. This reservoir will be one of the reservoirs which serves as the water source in a cascade tank system to supply water to the village in the down stream. This system is essential to maintain healthy water movement in terms of drainage after - 217 -
rainfall and to meet the domestic and agricultural water requirements by the villagers. However, these small and medium type drainage streams can be blocked or sometimes completely destroyed due to various human interferences and activities. This will lead to discontinuation of runoff flow from different places in the drainage system creating flooded conditions with rainfall. Stagnated water in different land pockets will be dried off during the dry period leaving the salts in the soil surface. This can lead to create salinity problem in the village too. Therefore, regular maintenance of drainage streams to facilitate smooth drainage flow is essential to reduce the development of floods and to reduce the effects of floods. This could be a reality if all the stakeholders in the villages are aware about these facts and give their fullest cooperation to clean and maintaine the natural water ways. Proper maintenance of water ways will not only important in controlling floods but also to assure the supplementary irrigation requirements in the dry period to control the effects of drought to the village community. If the water ways are blocked in different locations, supply of water to storage structures or to the main streams will be limited. This will lead to insufficient storage capacities in the storage bodies (village tanks) or streams to supply water to meet the demands in the dry period. Therefore, regular maintenance of proper drainage network in a village is useful in controlling the effects of possible drought to a village. In some instances due to the implementation of infrastructure development programmes like construction of new roads, buildings, village centers in the village, natural drainage ways can be blocked creating flood situation in different locations in a village with heavy rainfall. To prevent such situations, steps must be taken to link that area also to the existing natural drainage system as soon as the completion of infrastructure development project. The water way blocked with sand/ mud
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4. Pitcher and shallow water ponds
Crops need water throughout their lifespan to carry out their functions. However in some areas in any village the simple water source for the plants may be the sheer rainfall. In such situations either crops will die or undergo very hard situations with drought conditions. One way to overcome this situation is in-situ conservation of portion of the water which comes through rainfall to the land. Making of small depressions or wide ponds in different parts of the land to intercept runoff water is one way to keep the rain water for little longer in the ground. Water which is remaining in the pitcher will supply water steadily to soil moisture pool to meet the water demand by the crops and land in the close proximity. To support the water supply to the pitcher, eye brow shape bunds can be constructed to divert runoff water. Therefore, establishment of shallow water ponds and pitchers in the dry areas would be a viable alternative to reduce the effect of drought to the area. Steps of establishing pitcher irrigation for a coconut plant
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5. Stop filling of wetlands and paddy lands for commercial and other purposes With the increasing population, demand for land is also increasing tremendously. To meet the demand, some of wetlands or paddy lands has been converted to highlands by earth filling. This practice has been started at a slow pace in the past and gradually speeded up, reaching to an alarming rate at present. During this process, low laying areas which were existed to buffer the excess water flow from normal rainfall events were reduced or became unavailable to the village ecosystem. This has created a favorable environment to induce flood conditions since there is either no or less opportunity to the surface water to flow. Therefore adequate measures should be taken to preserve these wetlands by legislation with community support to reduce the filling of wetlands or completely stop if possible, to reduce the damage causing to village hydrology. Also if the situations where the filling cannot be avoided, adequate measures must be taken to regulate the runoff flow due to seasonal rainfall to reduce the development of flood conditions.
6. Grassed water ways Growing of grasses in leader drains helps to divert runoff water to the water storage structure at safe velocities. The grassed waterways improve the runoff water infiltration as well as prevent the soil erosion.
7. Conservation of river banks
Growing of bamboos to prevent river bank erosion
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8. Soil physical improvements Flood or drought always invariably deals with water. If the soil is capable of taking higher percentage of water from rainfall and retain it for a longer period, that soil can be considered as a good soil to overcome the effect of drought. Hence any physical improvement to the soil in improving the water retention capacity, increasing the infiltration rates and reducing the soil loss by water are considered as favorable steps in managing flood and drought conditions. Some of the strategies that can be practiced to make these improvements are as follows;
a. Incorporation of compost or organic waste Organic waste and compost will improve water holding capacity of the soil. Therefore soil will have higher percentage of soil moisture than a soil with no amelioration. This will have more opportunity to crops to withstand for drought condition. Also organic amelioration will improve the aggregate formation of soil and this will increase the infiltration rates and the stability of the soil. This will reduce the removal of surface soil (erosion) during heavy rains and also will improve the infiltration rate of the soil. Both will reduce the material transportation and the runoff flow to the down stream. This will reduce the chances of occuring floods and creation of situation for flood.
b. Mulching Mulching is the covering of soil surface using dead or live material. As dead mulching, paddy straw, other plant residues, animal waste or artificial material like polythine can be used. Creeping plants like sweet potato or some leafy vegetables can be planted as live mulches. Mulches will; ď Reduce the energy in the raindrops and this will reduce the dispersion of soil. ď Reduce the rate of runoff since mulch is trapping more water which comes from rainfall. ď Cut down the soil evaporation and thereby reduce the soil water loss. These all properties will improve the soil water condition which eventually helps to reduce the effect of drought. As mulches reduce the runoff flow and the rate, this will reduce the opportunities for floods as well. - 221 -
9. Management of flood control devices Flood control devices are usually one way gates which are located in flood prone areas to remove the excess water from the affected area. Flood control devices are available in the areas where an occurrence of flood is common or imminent with heavy rains. Flood control devices are also in operation in areas where natural drainage ways are not capable enough or not adequately support to take out excess water in an event with heavy rains or in an occasion where the spill ways of the village tanks or minor tanks are open to reduce the excess water in the tank.
Flood control device at Samanthurai, Ampara district
Efficiency of these devices will determine the probability of occurrence and the degree of damage of the flood. If the flood gates are capable enough of removing the water in an extreme event then the damage will be minimal. This shows how important the proper functioning of flood gates in controlling flood conditions. Therefore it is very important to make sure that all these flood protection devices are operating properly to minimize the effect of floods to any area. Periodic monitoring and maintenance of flood control devices must be practiced to obtain better control of floods.
10. Development and conservation of water resources As discussed earlier in this chapter drought or flood has direct relationship with the availability of water. Livelihood in a village has high dependency on water to carry out day to day functions. Therefore, water is needed in sufficient quantities but not excessively or below the requirement. Excessive availability of water above the requirement can lead for stagnation of water in different places leading for flooded conditions, - 222 -
unless otherwise it is properly managed and conserved for future use. Similarly absence or limited supply of water to meet the domestic and crop requirement indicate the drought condition. Therefore conservation of water by different means for the use in future is a prime importance in controlling floods and drought as well as to guarantee a better life in a village. Following are some of the important factors to consider when achieving above task at village level.
a. Development/ rehabilitation of village tanks Village tank is the main storage body to conserve water in a village. Ancient civilization was established taking the base as the village tank. Village tank was acted as the heart of the village life fulfilling almost all the domestic and agricultural water needs especially in the dry season. Therefore the villagers paid due and adequate attention to maintain the village tank system to harness the maximum benefit to the community. With the expansion of population and the socio economic changes in tank villages, community dependency on village tank system was diluted and adequate attention and care was not taken to maintain these tanks and the accompanied components of the system (catchment and command area). This has lead to several problems, such as reduction of storage area capacity due to siltation, reduction of catchment areas and malfunctioning of water diversion system from the tank. Result was the insufficient water supply for life saving irrigation for arable crops in the village to cope up drought situation. Further because of the reduction of tank capacity and malfunctioning of tank spill way system, especially during the heavy rainy period, development of flood condition in some parts of the command area can be observed. If this water can be stored in the village tank, the villagers will have good storage of water to irrigate their crops to reduce the effect of drought during the peak dry season. Also it will reduce the flow goes down as spillage from the tank which itself is a threat to the downstream villagers. Therefore, rehabilitation of existing village tanks is very important to increase the capacity and the supply of water in view of controlling flood and drought condition in the village. Following are some of the activities which can be put in to practice to increase the capacity and to strengthen the village tank based irrigation and drainage system. ď Ź ď Ź ď Ź
Periodic de-siltation of village tanks. Increase the tank capacity by deepening the tank. Take adequate care to protect the catchment area and to conserve the natural vegetations to reduce soil erosion. - 223 -
Re-establishment or conservation of traditional silt traps system in the village tank systems to reduce the soil transportation to tank. Rehabilitation of canal network to reduce losses and to increase hydraulic efficiency.
Canal in Ampara paddy fields
Rehabilitation of tank spill ways for safe removal of excess water. Establishment of proper operation and maintenance plan with the participation of all stake holders (Farmers, planners, politicians etc.).
In instances where village tanks are not existing, natural depressions could be developed into water bodies to store excess runoff water during the rainy season to mitigate drought conditions in the dry season.
b. Rain water harvesting Rain water harvesting is the capture, diversion, and storage of rainwater for irrigation and other uses. It is appropriate for large scale landscapes such as parks, schools, commercial sites, parking lots, and apartment complexes, as well as small scale residential landscapes. Rain water harvesting as a method of utilizing rain water for domestic and agricultural use is already widely used throughout the world. It is a method which has been - 224 -
used since ancient times and is increasingly being accepted as a practical method of providing potable water in development projects throughout the world. There are many benefits to harvesting rainwater: Water harvesting not only reduces water use and related costs, but also reduces off-site flooding and erosion by holding rainwater on the site. If large amount of water is held in pervious areas where water penetrates easily, some of the water may percolate to the water table. Rainwater is a clean, salt-free source of water for plants. Rainwater harvesting can reduce salt accumulation in the soil which can be harmful to root growth. When collected, rainwater percolates into the soil, forcing salts down and away from the root zone area. This allows for greater root growth and water uptake, which inturn increases the drought tolerance of plants. Limitations of water harvesting are few and are easily met by good planning and design. This shows the importance in practice or introduction of Rain Water Harvesting in saving water in a village. Water which is stored can be used for irrigation and other purposes to reduce the effect of drought during dry seasons. Several methods have been already introduced and practiced in the dry zone by several nongovernmental organizations, and other projects to harvest rainwater which is coming to the roof top. This is a simple method and widely popular in some of the districts like Anuradhapura, Ampara and Hambantota. Stored water is used for domestic use and to irrigate home gardens.
c. Promote water saving irrigation techniques Even though water is stored in a village tank or diverted to the village by other means, the final water productivity is depended on the use of water for irrigation in an economical manner. Usually village tanks are not meant for continuous supply of water throughout the year as major irrigation systems do in the country. Very often the quantity of water stored in village tank is limited and the incoming water flow to these tanks mostly depend on the amount of precipitation received in the rainy season (Maha season). Therefore it is very important to use this water, in an irrigation system in which the conveyance loss and the application loss are minimal. This will ensure irrigation water supply for a longer period from the water source to mitigate any effects if drought is occurred.
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Micro irrigation systems like drip and micro sprinklers would be an ideal selection to save water. However the quality of the water should be carefully studied before using these systems in order to ensure smooth operation. In an event like supplying water as a life saving irrigation for paddy, micro irrigation is not feasible. Lined canals should be used to divert water where ever possible in order to reduce conveyance losses and to save water in the reservoir for a longer period. If water is diverting from the domestic storage tank to a home garden instead of practicing surface irrigation, always encourage farmers to use PVC pipes or even a thick gauge polythine tubes to divert the water up to the target point to reduce the water loss. Using these techniques, stored water can be used preciously for a prolong period to minimize the effect of a drought.
Community pre providence
Development of farmer organizations An agricultural village is comprised of many farmers having different resource bases (land, knowledge and wealth). In some situation individual farmers can attend and resolve their problems without outside support. But in practical life, people experience many challenges that need the support of others. Especially an activity which requires the co-operation from many people in the society can be successfully completed if the people are united as a group. Agriculture is mostly weather dependent and will have to face natural calamities like floods or droughts which can destroy the crops partially or completely during a growing
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season. During such situations it is always easy to face as a group of farmers united in an organization than facing as individuals. Hence development of farmer organizations to face this type of challenges is vital and important. If the farmers are organized as a group during a flood, they can take decisions collectively to mitigate the situation for the benefit of majority of farmers. Immediate action on making either flood control structures or diversions in a disasters situation can be easily achieved if the organization is existed in active form. Farmer organizations can make higher and strong voice for the planners and policy makers to act promptly and accurately in a distress situation than complaining individually. If the farmers are organized as a group, rational and timely decisions on water saving irrigation from available water sources can be taken collectively and put in to practice easily to reduce the effect of drought. Through the farmers organizations farmers can plan their cropping plan based on the availability of water in the village tank to reduce the risk. Therefore establishment of farmer organizations and maintain them in active form in a village is very important to manage the land and water resources to reduce the effects of floods or drought situations.
Establishment of common resource pool In an incidence of a flood, urgent attention and action is needed to minimize the damage causing to man, crop, livestock and other physical wealth (roads, buildings etc.) in a village. To initiate appropriate action, immediately village itself must have all necessary manpower and other necessary tools. If the village has basic facilities to attend a natural calamity like flood in a common pool with easy access the villages can begin the necessary actions to minimize the damage until the authorities come with their plan of actions. Especially, this is a very important practice in villages where periodic floods are quite common. Required resources can be given to the farmer organization with proper training and by this way the villagers will be able to reduce the effect of flood in very efficient manner.
Development of contingency plan Damage from any unexpected natural calamity can be minimized if necessary actions and strategies are formulated in well advance, and being available with the community. For example flood can erupt in no time with extremely heavy rains. If the villagers are being well aware on the quickest way to remove the excess water in safe manner, then the effect can be minimized. Contingency plan is very important to mitigate natural calamities like floods or drought. - 227 -
Experience of other countries in reducing the effect of drought and floods Some of the activities carried out by other countries to reduce the effect of flood and drought is given below;
Khadin system - This system is popularly practiced in rocky hills and mountain areas that experience short rainy seasons in India. Stone bunds are constructed in the lower part of the hilly area. After a short rain, fertile silt is get deposited above the stone bund as a terrace. Short duration crops are planted in theses terraces and the moisture is sufficient to raise a successful crop even after a
short rainy season. By this way they reduce the effect of drought and raise a crop. In gentle sloping areas, long stone or earth bunds are constructed against the gradient along the contour lines. After sufficient rain is received, the area is just look like a shallow (one to two feet deep) reservoir. Cultivation practices starts from the upper end of the reservoir. Long duration drought tolerant crop species area planted in the upper end. After the cessation of rainfall, with the gradual receding of water level, medium duration crop species are planted in the middle area of the catena. In this manner, with further receding of impounded water, short duration and higher soil moisture required crop species are planted in the lower end. This method is popular in gently sloping arid and semi arid areas of India where there is no assured irrigation water facility. In sloping areas of the north eastern hill region of India, wide, long and sufficiently deep drains are constructed in the middle portion of the catena just below the natural forest area. These drains are usually made before the rainy season. Inner sides of these drains are plastered with tank silt to prevent water seepage and percolation. After a rainy season, sufficient amount of rain water is collected in these drains. Usually homestead and other agricultural activities are practiced in lowermost areas of the catena. Underground pipe system is constructed from these wide drains to the homesteads and agriculture lands. This water is used during the dry season for agricultural activities and domestic use. Check dams are constructed at seasonal rivers at regular interval in gently sloping areas of India to prevent the occurrence of floods. This also helps to recharge ground water as well as to keep the moisture level of adjacent lands to support agricultural production during the dry season.
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CHAPTER - 8
INDIGENOUS TECHNOLOGY TO MITIGATE THE RISK OF DROUGHT AND FLOOD
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ndigenous knowledge is the knowledge that the people in a given community have developed over time, and continues to develop. It is based on experience, often tested over centuries of use, adapted to local culture and environment, dynamic and changing. The development of indigenous knowledge systems covering all aspects of life, including management of the natural resources, has been a matter of survival for the people who generated these systems. Such knowledge systems are cumulative, representing generations of experience emerged through trial and error experiments. Over the course of history, large number of communities developed their own culture and lifestyle that are intricately tied up with nature and the local ecosystems. Indigenous knowledge is one of the products remained for centuries, firmly inbuilt into the belief systems, myths and folklore of society and it expresses the solutions to a series of problems that are faced by the villagers in their day to day life. It makes decisions regarding the use of resources and environmental conservation. It helps to avoid the incidence and negative impacts of natural disasters such as drought and floods. It provides guidance, on agricultural practices and food preservation, health care and a lot of other activities. It constitutes an environmental management system that is largely determined and led by community. Enforcement of these customs and norms is often ensured by social conformity and by codified threats.
Environmental compatibility Indigenous knowledge is a precious national resource that can facilitate the process of disaster prevention, preparedness and response in costeffective, participatory and sustainable ways. Hence a blend of approaches and methods from science and technology and from traditional knowledge opens avenues towards better disaster prevention, preparedness, response and mitigation. Indigenous knowledge in traditional agriculture is a mixture of many aspects derived from religious and spiritual origins, cosmic influence (astrology) and natural phenomena. Beauty of the traditional agriculture is that it has followed at many instances the rules, principles and phenomena of nature. This is the vital reason for the sustainability and the environmental compatibility of these systems, which prevailed for centuries under very harsh climatic conditions tolerating sudden shocks of natural events. Indigenous knowledge has two powerful advantages over outside knowledge- it has little or no cost and is readily available. Indigenous knowledge systems and technologies are found to be socially desirable, economically affordable, sustainable, and involve minimum risk to rural farmers and producers, and above all, they are widely believed to conserve resources. There are situations in which modern science is not appropriate, and use of simpler technologies and procedures are required. - 231 -
Thus, indigenous knowledge provides basis for problem solving strategies for local communities, especially the poor. Indigenous knowledge of Sri Lanka covers almost all aspects of biological and ecological systems as well as socio-economic and cultural patterns in the country. Of course, its main concern is human well - being. However, it does not take human beings as a separate entity. Indigenous knowledge has always placed human being within the context of total environment. As such it pays attention to all living things including plants, animals, water, soil and other natural resources. It tries to achieve human well- being without jeopardizing the environmental totality. For example, people are not permitted to destroy woods haphazardly, although clearing jungles is needed for cultivation. There is a jungle law to which people should obey. Forests cannot be burned without following certain rituals.
The farmer has to walk three times around the cleared forest shouting aloud, informing living beings who might be dwelling among fallen trees, that he is going to burn the forest.
He sets fire to the forest against the wind. This gives an escaping time for hidden animals and creatures. Pollution of water is also prohibited. Taking lives of other animals is also discouraged. In brief the indigenous knowledge of Sri Lanka is a humane system of knowledge. One cannot reject all practices of indigenous knowledge on the ground that they are not scientifically tested. By experience rural communities know that indigenous knowledge practices relating to various aspects
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of their lives are very effective. For example, herbal medicine and agricultural practices are still being used successfully by the rural communities. Perhaps the testing methods of modern science may not be sufficient to understand the principles behind indigenous knowledge practices.
Mitigation of drought and flood risks
The recurrent shortages of water for agriculture, animal husbandry and for domestic use, caused by droughts and dry spells had always been a serious natural and economic setback to the rural communities in the dry zone areas of Sri Lanka since ancient times. This is indicated by many references to the drought hazard frequently found in the historical chronicles such as Mahawansa and Chulawansa. The ancient irrigation reservoirs and the hydraulic society that once flourished in these areas exhibited a remarkable human adaptation to the problems created by droughts, floods and seasonal water shortages. In recent times, the renovation of ancient irrigation systems and the construction of new reservoirs of magnificent size, has significantly contributed to the mitigation of the adverse effects of drought and flood in many districts of the dry zone. The most common reaction to drought or flood condition appears to be to conserve food as much as possible by cutting down on the daily meals. Farmers usually keep seed paddy stock more than they need for use in any unexpected food shortage condition due to drought or flood. The traditional barn (atuwa, bissa), where they could store various grains was a common practice in the past followed as a strategy to face the drought hazard. Nowadays farmers are accustomed to sell the bulk of their produce soon after the harvest, keeping only a modest quantity for domestic consumption. This change of attitude is attributed to the fact that regular aid programs conducted by Government during last century have made an assurance of food availability during long droughts or sudden flood event to the community leading to a dependant mentality. The practice of providing drought relief work to affected families dates back to colonial times.
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The practice has continued up to now without undergoing much change either in the type of work undertaken or in the mode of organization. However, in attempting to adapt to drought or flood situations, the most common adjustments that the people use to make are; cutting down on daily meals; borrowing money; work as casual labourers; mortgaging jewellery; borrowing paddy; selling animals; selling other belongings; withdrawing children from school; mortgaging land; sending children to other places and selling land. During last few decades, convincing arguments were put forward by several writers to improve water management as a means of optimizing the use of available water resources.
Forecasting drought Through experience various communities of Sri Lanka have gathered climate forecasting indicators, which could differ from place to place. When people observe hot sun, dry weather condition and high evaporation during June, July and August, they believe that the drought period could continue even during maha season (September â&#x20AC;&#x201C; January) to occur disaster conditions. The rain-spell receiving during September (â&#x20AC;&#x2DC;Binara kaluwaâ&#x20AC;&#x2122;) is used to forecast the maha rainfall pattern by farmers in the North Central dry zone. If the Binara kaluwa does not bring a satisfactory rainfall, maha season would produce high rainfall and extend up to end of January. Under such circumstances much emphasis is placed on paddy cultivation under tank system. If there is much rainfall received during the September rain-spell, the rest of the maha season will not be successful with adequate rains. Under that situation farmers attempt to cultivate chena lands to depend much on other grains. Under usual conditions, farmers follow the normal schedule to cultivate both paddy and chena lands. From a study conducted in Hambantota District following indicators were found repeatedly as indicators for a forthcoming drought.
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1. Leaves of many trees show wilting unusually. 2. When they receive relatively low rainfall in a maha season, they
6. 7. 8. 9. 10.
expect a long drought until next maha season. Dry winds blowing across the village aggravates the drought condition. Tanks go dry early. When they observe fast drying of tanks they get prepared to face a drought. Dark clouds are hardly observed and the wind speed increases. Clouds do not move and hot condition prevails. Wind carries dust and makes surrounding warm. Before a drought people will notify that the morning is cold and it becomes warm gradually in the day time. People use to seek for tree shades when they feel uncomfortable due to hot condition during day time. The body is dehydrated due to dry wind rather than from hot sun. People hear unusual rattling sounds of lizards and hawks. Poisonous ants (black ants, brown ants etc.) come out of the ground. Nonpoisonous small kinds of ants move along ground surface with white eggs. Elephants roam around the village. Monkeysâ&#x20AC;&#x2122; shout cannot be heard.
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People can distinguish from which direction the moon rises. If moon rises over the land there will be a drought but when the moon rises over sea the rain will come soon.
There are two historically important tamarind trees in the Weliwewa village. According to the villagers, the well known English novel â&#x20AC;&#x2DC;Village in the Jungleâ&#x20AC;&#x2122; was written by the author Leonard Wolf by sitting under the shade of these two tamarind trees. Before rain begins the tamarind trees begin to produce golden colour tender leaves. This indicates that the rain comes soon. When the people could make above observations they believe that a continuous rainless condition would prevail until the next maha season.
Forecasting flood Flood occurs with heavy rains. People have adequate knowledge about flooding areas. They are sensitive when rainfall season begins on how it proceeds to develop a flood hazard. Some of the pre-signs they experienced are given below.
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1. People can hear unusual thundering sounds. It seems to be that the
sounds come from underground. The sound makes children frighten. 2. The surrounding shows strange dark look. It is darker than the 3. 4. 5. 6. 7. 8. 9. 10.
darkness one can see just before a usual rain spell. Dogs howl for a long time without having a rest. They bark as a group or from different locations in the village. People observe that white ants move upward along trees as a track. The surrounding becomes colder than that they feel in normal rainy days. People observe some kinds of insects such as grasshopper, dragonfly etc. move out of their places and fly around. Snakes attempt to creep into houses. People make special attention about snakes when observed. Ant tracks can be observed moving into houses. Clouds appear becoming darker than usual. People can observe lightning, but it does not follow any rains.
In night times people hear various sounds of snakes (python, wiper etc.) and animals (cattle, frog, fox, owl etc.). They believe that animals can feel that a flood is coming soon. People make following observations immediately before the flood comes. They will be active when they observe these signs understanding certainly - 237 -
that they must be ready to face the floods.
Crow-pheasant (atikukula) and cicada (rehaiya) start rattling. Water becomes muddy. Receiving rains on upper areas. Uproars of people. Raised water levels in rivers and streams. Cloudy appearance of mountains. Dense formation of clouds. Swallow fly as groups in the sky. Cattle roar in unusual times.
Water management The first extensive Sinhalese settlements were established along rivers in the northern dry zone of the Island. As cultivation of lowland rice was primarily dependent on unreliable monsoon rains in the historical periods, the Sinhalese constructed canals, channels, water-storage tanks, and reservoirs to provide an elaborate irrigation system to counter the risks posed by periodic drought. Such early attempts at engineering reveal the brilliant knowledge that these ancient people had on hydraulic principles and trigonometry. The discovery of the principle of the valve tower or valve pit (Bisokotuwa) for regulating the escape of water is credited to Sinhalese ingenuity more than 2,000 years ago. By the first century A.D, several largescale irrigation works had been completed. Conveyance of irrigation water over long distances needed efficient control over distribution and allocation between the proximal and tail-ends of the system. Smooth functioning of all hydraulic structures required efficient Cascading system (organizing of small tanks into cascading sequence)
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maintenance. Irrigation depending on micro-catchments required careful watershed management to reduce sedimentation and ensure catchment water yields. The land and water use system that developed over centuries to satisfy these requirements has been described as ‘cascading system’. Organization of small tanks into a cascading sequence within micro-catchments allowed greater efficiencies in water use. Drainage from the paddy fields in the upper part of the cascade flowed into a downstream tank for reuse in the paddy fields below. The system fully expressed the well known dictum by the King Parakramabahu (1153 - 1186 AD) that “not a single drop of water received from rain should be allowed to escape into the sea without being utilized for human benefit”. System management required community effort and coordination. A breach in the upper-most tank bund as a result of negligence or excess water would threaten the collapse of the entire sequence of tanks located below in the system. Similarly, if the capacity of a tank was increased arbitrarily by one village raising the bund or the spillway, it could inundate the lowermost paddy fields in an upstream village. Interdependency between villages in a cascade required well coordinated management of land and water resources.
The skills in irrigation technology possessed by the ancient people were unique for a small country like Sri Lanka. They developed the knowledge to construct long canals with extremely low gradient, such as the Yoda Ela, which carried water from Kalawewa to the city tanks of Anuradhapura along a canal 87km long. This Yoda Ela, which had a gradient of less than 10cm per km within its first 27km, continued to maintain itself as a natural stream. Some of the major ancient tanks, Yodawewa in Mannar District, were constructed to feed a large number of small tanks. - 239 -
All this agricultural activity requires plenty of water, and the ancestors were ingenious in their use of this precious material. There were, in all, five different types of “wewas”. First, there was the forest wewa, which was dug in the jungle above the village. It was not for irrigation but rather for the purpose of providing water for the wild creatures that lived in the jungle. They in turn did not come down into the village in search of water or to interfere with various agricultural activities of the villagers. The second type was the ‘mountain wewa’. This provided water for chena cultivation. The third kind was for erosion control and was called ‘pota wetiya’. Here the silt accumulated where it could be easily desilted. The fourth type was the ‘storage wewa.’ There were usually two of them. One was in use when the other was being maintained. They were connected to a large number of village wewas, which they fed and which in turn fed them when they overflowed. The ‘village wewa’ was the fifth type, and there was one for every “puranagama”. Land ownership of the paddy tract is distributed among villagers in a manner so that each farmer could have similar access and right to the irrigation water. Decision making on cultivation of a portion of paddy tract sharing proportionately among farmers in water shortage seasons (bethma cultivation) is a good example of their unity. Cultivation of the upper tank bed area (thavulu govithena) during extremely dry seasons taking adequate precaution to prevent sediment flow into tank is an example showing their cultivation wisdom. In low rainfall seasons, farmers resort to dry sowing (kekulama), which does not consume much irrigation water due to the optimum use of early rains. Best water management practices are discussed in a separate section.
Use of groundwater for agriculture was never practiced by them, and it assured the water security. An adequate storage was found in tanks to be utilized during dry period for all purposes and had been the only source of water for cattle and wild animals. There was a broad diversity in flora and fauna and the availability of water in the tank during the dry period assured the survival of them.
Land use adaptation Regarding land-use conservation, chena cultivation is a traditional practice, in which land was never over used or repeatedly cultivated season after season and year after year. Land was left to rest and covered again with plants and leaves to enable it to accumulate green manure. Mixed crop cultivation practice enables leguminous crops to restore nitrogen in the soil for other food plants. Knowledge of when to expect long or short rainy seasons enables the farmers to plan appropriately which crop is suited for a particular season. Traditional indigenous knowledge on soils and their reaction - 240 -
to water enabled the people to use each type of soil appropriately by planting the correct crops. The land use system associated with tank cascades demonstrated a profound knowledge of resource management in a challenging environment essentially transformed from natural ecosystems into agro-ecosystems. Integrated land and water resources management in ancient times is reflected in the zonation of land use within the micro-catchments. The tanks and the paddy fields occupied in the valleys comprised of Low Humic Gley soils with poor drainage had limited use other than for bunded paddy cultivation. Ridge summits, often strewn with rock outcrops and inselbergs, were converted into works of art and places of worship and spiritual retreat. The influence of Buddhism led to the establishment of sanctuaries early in history and the enduring protection of wildlife unusual in many parts of the world. The middle part of the catena between the ridge tops and valley bottoms was used for rain-fed chena farming, where Reddish Brown Earths proved ideal for growing many subsidiary seasonal food crops. Although in the modern context, chena cultivation is considered as a waste of resources, in the historical periods long fallow periods facilitated vegetative regeneration while extensive use of land for chena cultivation was sufficiently infrequent to avoid serious soil erosion and environmental damage. Moreover, village farmers spared large trees to provide shade and places for watch-huts. Small trees were lopped at breast height to enable them to sprout again at the end of the rainy season. Even during the Dutch period, introduction of cinnamon in chena lands was apparently done to enrich forest vegetation with cinnamon rather than to grow it as a monoculture. The ancient village was comprised of typical three fold land use system i.e. paddy field, home garden, and chena and the village was self-sufficient and provided a stable base for long-term use of natural resources. The ‘tank’ would appear to be synonymous with ‘village’, implying that each agricultural settlement had a tank and paddy field below it. - 241 -
The remainder of the ancient population lived either in the larger irrigation areas that developed subsequently, or in cities like Anuradhapura in the dry zone lowlands. The hill country and the wet zone attracted only a few settlements. In the hill country the people modified their life to suit the wetter and more rugged terrain. The paddy cultivation in the deniyas (valley bottoms) was irrigated during the drier periods through canals that collected water from springs in the hill slopes. Hills perform the function of the reservoirs, and the management of the watersheds necessarily formed an integral component of the agricultural enterprise. Different ecological segments of the slopes were recognized, as reflected from different local names such as Ovita, Ovilla, Ovilkanda etc. according to their location in the hill slope. Valley bottoms around which settlements arose were named after the valley with the suffix of deniya (Gurudeniya, Aladeniya, Peradeniya). At the lower segment of the catena, forest gardens were developed in the homesteads. Farther up, chena cultivation was practiced occasionally on a largely sustainable basis. Hilltops were kept permanently under thick forest cover, which helped control soil erosion and regulate water flow. The Kandyan Forest Garden became a man-made forest consisting of various fruits and other economically useful tree species such as nutmeg, cloves etc. It essentially copied diversity and intricate inter-relationships of the natural forest. Kandyan Forest Gardens are located between the valley bottoms and high slopes to avoid damp conditions and benefit from a deep soil cover and seepage of moisture from the upper regions. The micro-environment of a Kandyan homestead provides a suitable base for the community of human settlements in a wet montane setting. In Sri Lanka, best example to illustrate the environmental conservation - 242 -
to reduce the risks of natural disasters such as drought and flood is the tank-village land use system, which spreads all over the dry zone. The community frequently faces four natural disasters namely drought, flood, cyclone and epidemics. Their traditions, lifestyle agricultural practices, land use systems etc. have evolved over centuries to face these challenges imposed by the nature. Sustainability of the traditional tank-village system had been maintained in the past simply not only from structural maintenance. Each and every component of the eco-system was given due consideration. The attention was paid not only on Macro level land use patterns such as paddy land, settlement area, chena lands, tank bed etc. but also on Micro level land use patterns such as goda wala, iswetiya, gasgommana, perahana, kattakaduwa, tisbambe, kiul-ela etc. The figure below illustrates the geographical Macro level land use patterns setting of these different land uses, and their importance are discussed as follows.
“Gasgommana” – It is the naturally grown vegetation in the upstream land strip (Vaan gilma) above the tank bed, accommodating water only when spilling. Large trees such as kumbuk, nabada, maila, damba etc. and climbers such as kaila, elipaththa, katukeliya, kalawel, bokalawel etc. are found in this area. This is a natural vegetation and their seeds are floating on water. The gasgommana acts as a wind barrier reducing evaporation from the tank and lowering water temperature. It gets closure to the bund from either side where roots of large trees make - 243 -
water cages creating breeding and living places for some fish species. This strip of tree demarcates the territory between human and wild animals. Perahana – It is the meadow developed under gasgommana and filters the sediment flow coming from upstream chena lands. Iswetiya or potawetiya - An upstream soil ridge constructed at either side of the tank bund to prevent entering eroded soil from upper land slopes. Godawala - A manmade water hole to trap sediment and store water from small rainfalls during dry periods and it provides water to wild animals. Thawula – Upper part of the tank bed, where shallow water body is found on an almost flat area. Water will disappear during 2-3 months after maha rains. Wew-pitiya – This is the deep area of the water body, which accommodates major part of the tank water and it is covered with water for more than 8 months in an year. Mada-kaluwa – The portion of the water mass found during dry months of the year and located closer to the tank bund. This water cannot be moved through the sluice as it is below the spill level. Kuluwewa - A small tank constructed above the relatively large reservoirs only to trap sediment and not for irrigation purpose. It provides water for cattle and wild animals. Tis-bambe – It is a fertile land strip found around the settlement area (gangoda) and does not belong to anybody. Tree species such as ‘mee’, mango, coconut etc. are grown here in scattered manner. Mostly this area was used for sanitary purposes as the resting place of buffaloes. Buffaloes were used as a protection shield from wild animals and malaria. Kiul-ela – This is the old natural stream utilized as the common drainage. Along the kiul-ele tree species such as karanda, mee, mat grass, ikiri, vetakeya etc. are found. Few rare small fish species are also found in water holes along the kiul-ela. Most importantly kiul-ela removes salts and iron polluted water and improves the drainage condition of the paddy tract. Kattakaduwa – This is a reserved land below the tank bund. It consists of three different micro-climatic environments as, water hole, wetland; and dry upland and hence it supports a diverse vegetation. This land phase prevents entering salts and Ferric ions into the paddy field. The water hole referred to
as ‘yathuruwala’ minimizes bund seepage by raising the groundwater table. Villagers plant ‘vetakeya’ along the top of the bund to strengthen the bund stability. It is the village garden, where people utilize various parts of the vegetation for different purposes such as for fuel wood, medicine, timber, fencing materials, household and farm implements, food, fruits, vegetables - 244 -
etc. Specifically they harvest raw materials from this vegetation for cottage industries. With the disappearance of the features discussed above, the whole system would be subjected to deteriorate and ultimately collapse socially, physically and economically making vulnerable to disasters.
Agricultural best practices Some of the special features in the traditional agriculture are mentioned below. 1. Risks of farming due to factors such as heavy rainfall, drought, pest and diseases, damages from wild animals etc. are reduced through adoption of auspicious times and spiritual powers in farming operations, timely cultivation, crop management etc. 2. Maintenance of favouarable environment for crops by adopting appropriate conservation practices. 3. Maintenance of the land productivity by adjusting the farming practices with least disturbance to soil while addition of organic biomass. 4. Adoption of diverse crop combinations to cope up with the variation of climate, soil and other biotic as well as abiotic stresses. 5. Use of simple farm implements with lesser energy consumption. 6. Making use of natural processes to minimal use of inputs in cultivation i.e. introducing and maintaining crop diversity (to minimize pest attack), planting Mee (Madhuka longifolia) to attract bats to improve fertility, maintaining natural vegetation around the tank to conserve water storage etc.
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Traditional rain-fed farming
The ingenious knowledge acquired in the evolution of chena has many important qualities towards conservation and protection of natural resources. In the dry zone of Sri Lanka, clearing of chena land begins in July or August which are usually rainless dry months, and farmers prepare the land by burning the vegetation, which was initialy cut and heaped for drying. They complete the land preparation before mid September, where the first rain is expected. The chena is usually planted with a variety of crops such as finger millet, maize, mungbean, mustard, vegetables etc. at the beginning of maha season. During the yala season, chena is planted with sesame, some millets and pulses. After few seasons of cropping, the land is left to fallow. In the dry zone, in places where there is no limitation on the availability of forest land, the intensity of land use in chena cultivation does not exceed more than 10 percent. Identification of a suitable land for chena cultivation, selection of crops, sharing of the land block among the group, time of cultivation, crop management, protection and all other activities taking place in chena are merely based on sound scientific principals. Many agricultural practices found among rural communities in the past had aimed at minimizing the losses and failures of crop due to climate, wildlife and other natural disasters. However, with the launch of green revolution and intrusion of western culture into the rural life, centuries old indigenous wisdom began to disappear, mostly, forever.
The Bethma practice The bethma cultivation practice is adopted in poor rainfall seasons when the farmers cannot cultivate the entire paddy tract by using limited water in the tank. Farmers gather and decide to redistribute temporarily the upper portion of the paddy tract mostly in equal size. This provides a part of their food requirement which would otherwise end up in drastic shortage due to total abandonment of the paddy cultivation for that season. The practice assures the equity among landowners. The tank water could be utilized efficiently without incurring serious crop losses. Such a practice does not keep any assurance on the coming rainfall, which is not quite certain.
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Bethma might be practiced in combination with field rotation and the farmers may decide to cultivate either paddy or other field crops. This decision usually depends on the water level in the tank. In some cases the land distribution is proportional to the land size (usually 1/4 acre per acre of landholding) but in most cases it was found to be non-proportional (usually 1/4 acre per landowner, regardless the original share of land owned). Allocation of the plots is usually done by either the Vel vidane or the farmer organization.
Pangu for maintenance of the village tank Farmers divided the maintenance works such as cleaning of the bund, cleaning of the canals, small repairs etc. among themselves to complete work on time. This reduces the cost, creates a sense of responsibility, ownership and accountability. Performance of works is in good quality and working together could strengthen the social cohesion. Nevertheless, regular maintenance, attending all repairs ultimately could contribute to efficient water management and stability of the physical structures and collectively mitigate the risk of drought and flood.
Kekulama practice Dry sowing of paddy in â&#x20AC;&#x153;asweddumisedâ&#x20AC;? fields is known as kekulama in Sri Lanka. When dry sowing is done in upper portion of the land catena which is used for dry sowing, it is referred to as vee hena or goda hena. In the traditional kekulama method, the dry fields are ploughed with the country plough (sinhala nagula) to obtain a dispersed soil with burial of the weeds. At the inception of rains, dry seeds are sown with the anticipation of more rains soon. After sowing, the land is shallow ploughed to mix-up the seeds with soil. In some instances when the fields become adequately wet, the same kekulama could be practiced but sprouted seeds are being sown instead of mere dry seeds. In some paddy tracts and under some tanks, certain sections are sown to
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kekulama and when the tanks are full with rains, other sections of the paddy tracts are sown, with the normal wetland land preparation. This includes a sequence of events initiated from first ploughing followed by cleaning bunds, re-plastering bunds, second ploughing, puddling, leveling, preparing a shallow channel system to drain the fields, and end up with sowing of sprouted seeds. The recent studies have revealed that delaying cultivation without adopting kekeluma method would lead to high irrigation requirement failing to utilize a considerable portion of the effective seasonal rainfall for the cultivation.
Cosmo-spiritual dimension of traditional agriculture Traditional agriculture in Sri Lanka is not merely a bio-physical process as found in western agriculture. The recent development of agriculture and irrigation sectors has thoroughly ignored the fact that our agricultural civilization has evolved through a three dimensional process. In addition to the bio-physical farming (physical structures and practices to raise a crop, manage and harvest), the agriculture has been strongly blended with socio-cultural and cosmospiritual dimensions. There are three categories of traditional practices in cosmo-spiritual dimension. The first group is based on astrology, the second on the powers of the spirits and Gods, and the third involves the chanting of verses and the use of specific symbols. In many cases these three categories work in harmony.
Astrological practices In every village there is at least one astrologer who reads the ancient texts and advice people when they are trying to plan important events. Some astrologers are generalists, while others specialize in health, agriculture and helping travelers. Astrology plays a significant role in the lives of Sri Lankan people. Rural people in particular, have great faith in astrology and consult astrologers before embarking on any significant enterprise in their personal, educational or professional life. Astrology also plays a dominant role in agriculture, especially in the cultivation of rice. Farmers believe that certain days are good for beginning cultivation. They also avoid certain days which they consider inauspicious or unlucky. Usually a Sunday is chosen to initiate work relating to paddy cultivation. The work is begun on an auspicious day at an auspicious time. Most farmers follow the astrological calendar or â&#x20AC;&#x153;pancha suddiyaâ&#x20AC;? to ensure success and avoid bad luck.
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Spirits and Gods If the people realize that the issue cannot be addressed by their strategies then they expect the support of Gods and spirits. One such example is that all farmers visit the temple and make offerings before they start cultivating their crop. They participate in the communal rituals held at the temple. After the harvest, farmers perform a ritual in the field before use. They believe that such practice could please the unseen spiritual forces. These activities are still taking place in some rural villages. Since ancient times, the rituals have been used in Sri Lankan agriculture to support crop growth, animal husbandry and to chase away wild animals or pests that damage the crops. The combination of spiritual practices, astrology and eco-friendly technologies have become customs. Despite the impact of the green revolution, many of these spiritual practices still exist, but in some instances, their full meaning is not fully understood by the young farmers. One of the most important rituals is the pooja or offering, carried out during the annual festival that is called Mangalya. In many villages this festival is held at the devala, a specific place, usually on the bund of the village water reservoir, the tank. On the day of the festival all items which are collected and purchased are taken in a procession to the devale premises. All men, women and children of the village are expected to participate to the festival.
Chanting and use of symbols Under this sub category there are different types of practices, that could be grouped into pirith, manthra, yanthra and kem.
Pirith Pirith is Buddhaâ&#x20AC;&#x2122;s teaching for laymen and involves chanting specific verses in a group. Each verse deals with some aspect of good living. Some of these prescriptions are used for crop protection. The verses are used to charm sand and water. These are then sprinkled thinly over the field. Chanting specific verses extracted from Buddhist teachings is done in a group. In some areas symbols are painted on an ola leaf and hung in the corners of the field. However, the performer is said to be having a pious life and he should refrain from robbery, sexual misbehaviour, eating animal protein or consuming alcohol.
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Manthra The manthra is also chanting with specific sounds repeating the same version for a specific number of times. This causes a vibration in the environment. This influences the spirits to bring about the desired effect. In the mantra Gods or religious leaders, like Lord Buddha or the Prophet Mohammed, can also be called upon and their great achievements are recalled. A mantra is a certain type of verse, a combination of carefully selected sounds that together create a nucleus of spiritual energy. It functions as a magnet or a lens to attract or create spiritual vibrations. Mantras existed in this substrate and caused the creation of the universe. Early seers and sages have made a study of the effects of sound or vibrations and in this way composed the specific combinations of sounds that are now established as mantras. In the tradition, several spiritual practices have been developed to relate to the spirits of the different living organisms. Mantras play an important role there. The spiritual leaders know what mantras to use to achieve specific effects. The mantras address some invisible spirits who are believed to grant redress. The words used, the sounds made and the rhythm of the reciting is important. Some mantras are very short and may consist of just a few words. Mantras are used in agriculture to obtain higher yields and also to protect crops from damage by pests and wild animals.
Yanthra A symbolic drawing preferred by a particular spirit is hung or kept in a specific place expecting the blessings of unseen power to carry out their activities or to live without any threats. A drawing of yantra involves following certain laws. If these laws are not carefully followed, not only will the yantra have no effect, but evil things may also happen. For the spirit to occupy the yantra it has to be enlivened with specific verses, or mantras. Yantras are symbols that have been given the powers by mantra or pirith chanting by a sacred person. It can have the form of a drawing, an idol or a structure. Some yantras are inscriptions on a thin strip of copper or palm leaves. These inscriptions can represent gods, spirits or be abstract geometrical figures or texts in Sanskrit or another language. Yantras are used to secure protection from oneâ&#x20AC;&#x2122;s enemies, the anger of the gods or evil spirits, ill effects of planets, forces of nature, envy and the evil eye. They can also help to ensure good crops or good health. - 250 -
In agriculture, the use of yantras is widespread. Generally a yantra is placed in the centre of the rice threshing floor. An abstract geometrical drawing is used: three concentric circles and eight radial lines with different drawings on the outside: The yantra is placed or drawn on the threshing floor, certain items such as an oyster shell, a coconut, a piece of iron are placed on it, together with a few bundles of paddy. During threshing operations no item is referred by its real name. The idea is to mislead the spirits so that they may not know that a threshing operation is going on. Other yantras are used for crop protection against flies, rats, and for animal health.
Kem karma The practice of kem is very widespread in rural Sri Lanka. A kem is a kind of practice, technique or custom that is followed in order to obtain some favourable effect such as relief from a specific illness. For example, washing in a pool of water immediately after a crow washes in that pool is believed to bring relief to people suffering from certain infirmities. A requirement in this kem is that the patient should wash without speaking or making much noise. Some kems combine the use of astrology with the use of certain plants or herbs. Other kems depend on the use of specific plants and mantras. These traditional practices have survived because they must be effective. If these had no real effect, they would have disappeared long ago. There are also kems that do not involve any belief in spiritual beings or gods. These kems are based on a careful observation of nature and natural phenomena. Some kems are mechanical methods, like the lighting of fire torches. These torches are made using a piece of saffron robe for the wick and sticks of trees wara (Calatropis gigantea), kadura (Pagiantha dichotoma) or gurula (Leea indica) for the handle. The wick is dipped in butter oil or fat. A number of these torches are lighted and kept burning for about two hours at dusk. There are various conditions that have to be met to make the working of kems successful. For example, the farmer should not visit the field for a specific period after being treated. This period of prohibition may be one, three or seven days. With some kems, women are prohibited from entering the field altogether, while other kems have to be performed by women only or even by pregnant women only. The effectiveness of a kem can be nullified if the person is exposed to a killa or impurity caused by eating certain food (especially meat). Attending a funeral also causes impurities. Another major impurity is associated with womenâ&#x20AC;&#x2122;s menstruation.
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Mitigation methods in other countries Kenya
Kenya traditional home
Each community has an array of early warning indicators and well-developed structures through which the wisdom of the community is applied to deal quickly and efficiently with disasters. In Kenya, for example, the Banyala community in Budalang, on the shores of Lake Victoria has a well-organized system for mitigating impending disasters. There are elders who dealt with rainfall prediction and early warning. Each homestead has a dugout canoe ready for transport in case of heavy flooding. Each community is also required to dig trenches to control the water around the homestead and around farmlands. In addition, they are required to avoid ploughing along the lake shores when heavy flooding is predicted and are advised to catch fish during the April-August rainy period when fish is plentiful and preserve them by drying and smoking for use in times of scarcity. When crocodiles start laying their eggs on river banks at higher ground, that is a sign to the community of impending floods. When floods come, those living on the highlands are expected to accommodate neighbours displaced by the floods in the lowlands. Recent studies in Kenya on the application and use of traditional knowledge in environmental conservation and natural disaster management cited examples of areas where such knowledge is still prevalent and harnessed.
Swaziland In Swaziland, where drought and occasional floods are common disasters, communities use various methods to predict disasters. For example, they use the height of the nests of the emahlokohloko bird (Ploceus spp.) on trees growing by river banks to predict floods. When floods are likely to occur, the nests of the emahlokohloko are very high up on the trees and when floods are unlikely the nests are low down. The Swazis also use the cry of certain birds to predict rain, and yields of certain wild fruit plants to - 252 -
predict famine. Other indigenous methods used by the Swazis to predict natural hazards include wind direction, the shape of the crescent moon and the behaviour of certain animals. Moth numbers can predict drought. The position of the sun and the cry of a specific bird on trees near rivers may predict onset of the rainy season for farming. The presence of certain plant species (for example, Ascolepis capensis) indicates a low water table.
Tanzania In Tanzania, animals feature prominently in prognosis of drought and famine. For instance, by reading signs on goat intestines, specialized Maasai elders can divine drought and predict incoming famine or diseases.
Russian Federation In the regions of Nenets Autonomous Okrug and Kamchatka of the Russian Federation, the hunters, gatherers and herders interviewed in a UNEP study described how careful observation of the behaviour of animals, and of the appearance and colour of the sky, is used as early warning of natural disasters. As stated by a hunter from Kamchatka, when the dogs start rolling on their backs on the snow and the crows circle in flocks and then hide, a blizzard is coming.
Indonesia In Indonesia, the Simeulue community (population 80,500) of farmers, fishermen and traders close to the epicentre of the 26 December 2004 tsunami survived by rushing to nearby hills in response to long held indigenous knowledge on the behaviour of their buffaloes. Only seven people from the community lost their lives, compared to 163,795 that died across the rest of Indonesiaâ&#x20AC;&#x2122;s northern Aceh province. In recognition of their application of indigenous knowledge in saving thousands of lives, the community, through their leader, was awarded the prestigious United Nations Sasakawa Award for Disaster Reduction.
In India, rural communities play an important role in mitigating the effects of drought by using traditional drought-coping methods such as construction of ponds and dams (anicuts) to save the rain water, which would otherwise be lost due to surface runoff, thus mitigating the effect of drought. Indigenous knowledge has also been used in mitigating the impacts of earthquakes and cyclones in India. The traditional circular homes are known to be resistant to earthquake and are also considered to be cyclone proof. They are constructed with local materials such as sun-dried bricks and straw branches (khip) of the babool tree.
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Japan Prior to the onset of typhoons, communities living in the typhoon prone areas of Saigasaki and Tano districts of Japan keenly observe the quick eating habits of birds. They carefully observe the tsubane (swallows), which normally build their nests at the second floor of houses in the neighbourhood; when they build their nests at the third or fourth floors, it indicates that the forthcoming typhoon would be big and strong with a high water surge. The communities also apply the same rule for honeycombs. Their predictions are known to be highly accurate.
Bangladesh In Bangladesh, local communities prepare movable cookers (chula) to preserve dry food, fuel, and fodder before floods. They also prepare boats and rafts for emergency rescue operations. To cope with cyclones and storm surges, the communities also apply appropriate response measures such as storing dry food and valuable seeds, stocking fuel, constructing bamboo mat-based platforms (matchas), and many other measures that go a long way in saving lives and property.
Burkina Faso In Burkina Faso, the Mossi farmers use their indigenous knowledge to abate problems of drought. They build lines of stones (bunds) on their cultivated land to construct terraces and pits that conserve water. They also fill the bunds with organic material to increase soil fertility. The semipermeable bunds allow for a gradual seeping in of the water and prevent run-off caused by the scarce but highly intensive rains, thus reducing the risk of crop failure and soil erosion. In the disastrous drought years of 1983 and 1984, crops grew on land with bunds, while on adjoining fields nothing could grow.
Studies done in the South Pacific Small Island Developing States (SIDS) indicate that despite the influx of outside aid, indigenous communities still show considerable resilience to natural disasters. Strong levels of intracommunity cooperation exist and many indigenous groups still utilize traditional building and food preservation techniques to help them escape the ravages of disasters in the region. There is also a growing mutual assistance amongst indigenous groups in the SIDS, not only in sharing resources when disasters occur but also in building disaster management capabilities. This shows that indigenous groups are able to adapt to change and their knowledge is extremely valuable in ensuring recovery. All these examples underscore the importance of harnessing indigenous knowledge as a crucial element in the management of natural disasters, particularly at the community level.
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In Africa, local communities had well-developed traditional indigenous knowledge systems for environmental management and coping strategies, making them more resilient to environmental change. This knowledge had, and still has, a high degree of acceptability amongst the majority of populations in which it has been preserved. These communities can easily identify with this knowledge and it facilitates their understanding of certain modern scientific concepts for environmental management including disaster prevention, preparedness, response and mitigation. Globally, there is increasing acknowledgement of the relevance of indigenous knowledge as an invaluable and underused knowledge reservoir, which presents developing countries, particularly Africa, with a powerful asset in environmental conservation and natural disaster management. Specifically, from time immemorial, natural disaster management in Africa has been deeply rooted in local communities which apply and use indigenous knowledge to master and monitor climate and other natural systems and establish early warning indicators for their own benefit and future generations. In the traditional African worldview, environmental resources (land, water, animals and plants) are not just production factors with economic significance but also have their place within the sanctity of nature. Certain places have a special spiritual significance and are used as locations for rituals and sacrifices, for example, sacred grooves, shrines, mountains and rivers. These locations are quite often patches of high biodiversity which are well conserved and protected by the community. For the traditional people of Northern Ghana, gods, spirits, shrines, ritual crops and animals, food items and cash crops are all inter-related.
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Soil series, associations and complexes found in different districts
oils in Sri Lanka are so heterogeneous and therefore a vast variation of soil properties can be found in small distance depending on the agro ecological condition, land form, drainage condition and parent material. Therefore major soil series, associations and complexes are listed below under each district and the small description of the properties of soil series are followed.
Aluthwewa-Hurathgama Association Aruvi Series associated with undifferentiated soils of alluvial origin with variable texture and drainage Gambura-Borupana-Mawillu Association Medawachchiya-Aluthwewa-Divulwewa-Hurathgama-Nawagathtegama Association Medawachchiya-Aluthwewa-Kahatagasdegeliya Association Medawachchiya-Ranorawa-Elayapattuwa-Hurathgama-Nonagama Association Tonigala-Anamaduwa-Nawagattegama Complex Willpattu-Gambura-Borupana-Mawillu Association
Aluthnuwara-Manampitiya Association with undifferentiated soils of alluvial origin Bibele-Dombagahawela Complex Gal Oya Series associated with undifferentiated Negombo-Gambura-Siyambala-Puttulam Association Negombo-Nillaweli-Valaichchenai-Illuppaiyadichche Complex Nonagama-Ranna-Ketegal Ara-Sevenagala Complex Siyambalanduwa-Muthukandiya Association with bed rock exposures Siyambalanduwa-Bibele-Lithosols Complex with bed rock exposures Siyambalanduwa-Arantalawa-Akkaraipattuwa-Damana association Siyambalanduwa-Arantalawa-Damana Complex Siyambalanduwa-Arantalawa-Hingurana-Damana Complex Siyambalanduwa-Bibile-Lithosols Complex with bed rock exposures Siyambalanduwa-Mutukandiya Association Siyambala-Puttulam Association Timbolketiya-Pallagama Association Ulhitiya-Kuda Oya Association with bed rock exposures Ulhitiya-Kuda Oya Association Welikanda-Galwewa-Alawakumbura-Omadiyamadu Association Undifferentiated Soils of Alluvial origin with variable texture and drainage
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Boralu-Madabokka Complex Boralu-Gampaha Association Galigamuwa-Homagama Complex Galigamuwa-Pallegoda Complex Negombo-Katunayake Association Palatuwa-Wagura-Madabokka Complex Pallegoda-Dodangoda-Homagama Complex Pallegoda-Dodangoda-Boralu-Gampaha Association Pugoda Series (Flood) Ratupasa-Katunayake Association
Aluthnuwara-Manampitiya associated with undifferentiated soils of alluvial origin Gal Oya Series associated with undifferentiated Kaduruwela-Seruwila-Siyambala Association Negombo-Nillaweli-Valaichchenai-Illuppaiyadichche Complex Siyambalanduwa-Arantalawa-Akkaraipattuwa-Damana association Siyambalanduwa-Arantalawa-Damana Complex Siyambala-Puttulam Association Ulhitiya-Kuda Oya Association Ulhitiya-Welikanda-Mutugal-Galwewa-Alawakumbura Welikanda-Galwewa-Alawakumbura-Omadiyamadu Association Undifferentiated Soils of Alluvial origin with variable texture and drainage
Boralu-Madabokka Complex Dodangoda-Boralu Association Dodangoda-Agalawatta-Gampha Complex Madabokka-Gampaha Association Malaboda-Weddagala-Pallegoda Lithosols Complex Malaboda-Pallegoda Association Negombo-Katunayake Association Palatuwa-Wagura-Madabokka Complex Pallegoda-Dodangoda-Gampaha Association Ratupasa-Katunayake Association Wagura-Palatuwa Complex Undifferentiated Soils of Alluvial origin with variable texture and drainage
Aluthnuwara-Manampitiya associated with undifferentiated soils of alluvial origin with variable texture and drainage Badulla-Lithosols Complex Badulla-Mahawaletenna Complex Bandarawela Series Bibele-Dombagahawela Complex Hambagamuwa-Ketegal Ara Association
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Horton-Lithosol Complex Mahawalatenna-Hunnasgiriya-Weligepola Complex Nuwaraeliya-Hortan-Lithosols Complex Ragala Series Rahugala-Mahawalatenna-Badulla-Lithosols Complex Ulhitiya-Kuda Oya Association with bed rock exposures Ulhitiya (rolling)-Lithosols Complex with bed rock exposures Ulhitiya-Kuda Oya Association Welimada Lithosols Complex
Aluthwewa-Hurathgama Association Boralu-Gampaha Association Galigamuwa-Pallegoda Complex Minuwangoda-Gampaha Association Negombo-Katunayake Association Pallegoda-Dodangoda-Homagama Complex Pugoda Series Ratupasa-Katunayake Association Wagura-Palatuwa Complex
Calcic Red Yellow Latosols Regosols Soils on Recent Beach and Dune Sands Solodized Solonetz and Solonchacks
Beliatta-Okewela-Modarawana Complex Boralu-Madabokka Complex Dodangoda-Boralu Association Malaboda-Weddagala - Pallegoda Lithosols Complex Negombo-Katunayake Association Negombo-Gambura-Siyambala-Puttulam Association Nonagama-Ranna-Ketegal Ara-Sevenagala Complex Ranna-Ketagal Ara Association Ranna-Ketegal Ara-Sevenagala Association Siyambalanduwa-Muthukandiya Association with bed rock exposures Siyambalanduwa-Mutukandiya Association Timbolketiya-Pallagama Association Walawe-Ketegal Ara Association Walawe-Mahagal Ara-Ketegal Ara-Sevenagala Association Undifferentiated Soils of Alluvial origin with variable texture and drainage
Boralu-Madabokka Complex Boralu-Gampaha Association
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Dodangoda-Agalawatta-Gampha Complex Madabokka-Gampaha Association Malaboda-Weddagala-Pallegoda Lithosols Complex Malaboda-Pallegoda Association Negombo-Katunayake Association Palatuwa-Wagura-Madabokka Complex Palatuwa-Wagura-Madabokka Complex Pallegoda-Dodangoda-Homagama Complex Ratupasa-Katunayake Association Wagura-Palatuwa Complex Undifferentiated Soils of Alluvial origin with variable texture and drainage
Akurana-Kiribathkumbura Association Galigamuwa-Homagama Complex Gampola Series Hunnasgiriya Lithosols Complex with Kandy-Galigamuwa-Lithosols Complex Kandy-Matale Association Maskeliya-Mattekele-Lithosols Complex Mattekele Series Mawanella-Kandy-Kiribathkumbura Association Ukuwela-Matale Association Ulhitiya-Kuda Oya Association with bed rock exposures Wegala-Hunugala-Kundasale Mahaberiyatenna Complex
Galigamuwa-Homagama Complex Galigamuwa-Pallegoda Complex Kandy-Galigamuwa-Lithosols Complex Kandy-Matale Association Malaboda-Lithosols Complex Maskeliya-Mattekele-Lithosols Complex Mawanella-Kandy-Kiribathkumbura Association Minuwangoda-Gampaha Association Pallegoda-Dodangoda-Homagama Complex Pallegoda-Dodangoda-Boralu-Gampaha Association
Gambura-Borupana-Mawillu Association Mampuri-Siyambala-Puttulam Association Mampuri-Siyambala-Puttulam AssociationMullaittivu-Tanniyuttu-Vattappalai Association Negombo-Nillaweli-Valaichchenai-Illuppaiyadichche Complex Negombo-Puttulam Association Siyambala-Puttulam Association Soils on Recent Beach and Dune Sands Regosols Undifferentiated Soils of Alluvial origin with variable texture and drainage
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Aluthwewa-Hurathgama Association Andigama-Willattawa-Gampaha Association Aruvi Series associated with undifferentiated soils of alluvial origin with variable texture and drainage Galigamuwa-Homagama Complex Kandy-Matale Association Kiruwana-Kurunegala-Batalagoda Association Kiruwana-Melsiripura Association Kuruwita-Kuliyapitiya-Kurunegala-Batalagoda Association Maho-Wariyapola-Balalla Association with bed rock exposures Mawanella-Kandy-Kiribathkumbura Association Medawachchiya-Ranorawa-Elayapattuwa-Hurathgama-Nawagattegama Association Minuwangoda-Gampaha Association Pallegoda-Dodangoda-Homagama Complex Siyambalangamuwa Wewa Tonigala-Anamaduwa-Nawagattegama Complex Welipelessa Series Welipelessa-Palugaswewa Association Undifferentiated Soils of Alluvial origin with variable texture and drainage
Beliatta-Okewela-Modarawana Complex Boralu-Madabokka Complex Dodangoda-Boralu Association Malaboda-Weddagala-Pallegoda Lithosols Complex Negombo-Katunayake Association Pallegoda-Dodangoda-Gampaha Association Wagura-Palatuwa Complex Undifferentiated Soils of Alluvial origin with variable texture and drainage
Akurana-Kiribathkumbura Association Aluthnuwara-Manampitiya Association with undifferentiated soils of alluvial origin Aluthwewa-Hurathgama Association Aluthwewa-Hurathgama Association Badulla-Mahawaletenna Complex Erosional remnents (Inselberg) Hunnasgiriya Lithosols Complex with bed rock exposures Kandy-Matale Association Kiruwana-Melsiripura Association Medawachchiya-Aluthwewa-Divulwewa-Hurathgama-Nawagattegama Association Medawachchiya-Aluthwewa-Kahatagasdegeliya Association Ukuwela-Hunugala-Matale Complex Ukuwela-Matale Association Ukuwela-Hunugala Matale Association Ulhitiya-Kuda Oya Association with bed rock exposures Ulhitiya (rolling)-Lithosols Complex with bed rock exposures
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Ulhitiya-Kuda Oya Association Undifferentiated Soils of Alluvial origin with variable texture and drainage
Gambura-Borupana-Mawillu Association Mampuri-Siyambala- Puttulam Association Medawachchiya-Ranorawa-Elayapattuwa-Hurathgama-Nawagattegama Association Medawachchiya-Tadaratu-Cheddikulam-Hurathgama-Nawagattegama Association Negombo-Puttulam Association Pallagama-Siyambala Complex Rock Knob Plains Siyambala-Puttulam Association Willpattu-Gambura-Borupana-Mawillu Association Undifferentiated Soils of Alluvial origin with variable texture and drainage
Badulla-Lithosols Complex Badulla-Mahawaletenna Complex Bibele-Dombagahawela Complex Erosional remnents (Inselberg) Gal Oya Series associated with undifferentiated Hambagamuwa-Ketegal Ara Association Hambagamuwa-Ketegal Ara-Sevenagala Association Hambagamuwa-Ketegal Ara-Sevenagala Association Mahawalatenna-Hunnasgiriya-Weligepola Complex Rahugala-Mahawalatenna-Badulla-Lithosols Complex Ranna-Ketegal Ara-Sevenagala Association Siyambalanduwa-Muthukandiya Association with bed rock exposures Siyambalanduwa-Bibele-Lithosols Complex with bed rock exposures Siyambalanduwa-Arantalawa-Damana Complex Siyambalanduwa-Arantalawa-Hingurana-Damana Complex Siyambalanduwa-Bibile-Lithosols Complex with bed rock exposures Timbolketiya-Pallagama Association Ulhitiya-Kuda Oya Association with bed bed rock exposures Walawe-Mahagal Ara-Ketegal Ara-Sevenagala Association
Gambura-Borupana-Mawillu Association Medawachchiya-Aluthwewa-Divulwewa-Hurathgama-Nawagattegama Association Medawachchiya-Tadaratu-Cheddikulam-Hurathgama-Nawagattegama Association Mullaittivu-Tanniyuttu-Vattappalai Association Negombo-Nillaweli-Valaichchenai-Illuppaiyadichche Complex Siyambala-Puttulam Association Regosols Undifferentiated Soils of Alluvial origin with variable texture and drainage Rock Knob Plains
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Badulla-Mahawaletenna Complex Galigamuwa-Homagama Complex Horton-Lithosol Complex Kandy-Galigamuwa-Lithosols Complex Malaboda-Lithosols Complex Maskeliya-Mattekele-Lithosols Complex Mattekele Series Nuwaraeliya-Hortan-Lithosols Complex Ragala Series Rikillagaskada Series Ulhitiya (rolling)-Lithosols Complex with bed rock exposures Wegala-Hunugala-Kundasale Mahaberiyatenna Complex Welimada Lithosols Complex
Aluthwewa-Hurathgama Association Andigama-Willattawa-Gampaha Association Aruvi Series associated with undifferentiated Mampuri Series Mampuri-Siyambala- Puttulam Association Medawachchiya-Ranorawa-Elayapattuwa-Hurathgama-Nawagattegama Association Minuwangoda-Gampaha Association Negombo-Katunayake Association Negombo-Puttulam Association Palatuwa-Wagura-Madabokka Complex Ratupasa-Katunayake Association Siyambala-Puttulam Association Tonigala-Anamaduwa-Nawagattegma Complex Welipelessa Series Welipelessa-Palugaswewa Association Willpattu-Gambura-Borupana-Mawillu Association Undifferentiated Soils of Alluvial origin with variable texture and drainage
Aluthnuwara-Manampitiya Association with undifferentiated soils of alluvial origin Aluthwewa-Hurathgama Association Kaduruwela-Mutugala-Ulhitiya-Kuda Oya-Complex Medawachchiya-Aluthwewa-Kahatagasdegeliya Association Ukuwela-Hunugala Matale Association Ulhitiya-Kuda Oya Association with bed rock exposures Ulhitiya (rolling)-Lithosols Complex with bed Ulhitiya-Kuda Oya Association Ulhitiya-Welikanda-Mutugal-Galwewa-Alawakumbura Welikanda-Galwewa-Alawakumbura-Omadiyamadu Association Undifferentiated Soils of Alluvial origin with variable texture and drainage
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Badulla-Mahawaletenna Complex Beliatta-Okewela-Modarawana Complex Galigamuwa-Homagama Complex Galigamuwa-Pallegoda Complex Hambagamuwa-Ketegal Ara-Sevenagala Association Horton-Lithosol Complex Mahawalatenna-Hunnasgiriya-Weligepola Complex Malaboda-Lithosols Complex Malaboda-Pallegoda-Dodangoda-Homagama Complex Malaboda-Weddagala-Homagama Complex Malaboda-Weddagala-Pallegoda Lithosols Complex Malaboda-Pallegoda Association Maskeliya-Mattekele-Lithosols Complex Pallegoda-Dodangoda-Homagama Complex Pallegoda-Dodangoda-Boralu-Gampaha Association Ranna-Ketegal Ara-Sevenagala Association Timbolketiya-Pallagama Association Timbolketiya-Pallagama Association Walawe-Ketegal Ara Association Walawe-Mahagal Ara-Ketegal Ara-Sevenagala Association Undifferentiated Soils of Alluvial origin with variable texture and drainage
Aluthnuwara-Manampitiya associated with undiffer Kaduruwela-Mutugala-Ulhitiya-Kuda Oya-Complex Kaduruwela-Seruwila-Siyambala Association Medawachchiya-Aluthwewa-Divulwewa-Hurathgama-Naw Medawachchiya-Aluthwewa-Kahatagasdegeliya Association Negombo-Nillaweli-Valaichchenai-Illuppaiyadichche Complex Siyambala-Puttulam Association Ulhitiya-Welikanda-Mutugala-Galwewa-Alawakumbura Complex with rock knob plains Undifferentiated Soils of Alluvial origin with variable texture and drainage
Medawachchiya-Aluthwewa-Divulwewa-Hurathgama-Nawagattegama Association Medawachchiya-Tadaratu-Cheddikulam-Hurathgama-Nawagattegama Association Undifferentiated Soils of Alluvial origin with variable texture and drainage
Soil Series in the Dry Zone ALUTHWEWA SERIES
RBE, a deep well drained soil found in undulating terrain. Texture is sandy loam to sandy clay loam throughout the soil profile. Presence of a gravel layer is rich in quartz is a limitation. Medium available soil moisture content and therefore susceptible to drought condition. Susceptible to soil erosion and should not expose the surface during the
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rainy season. Low OM content, but good in available nutrient. Homesteads/ Shrub jungle.
RBE, Ranorawa series is deep well drained soil in undulating terrain. Texture is sandy loam to sandy clay loam throughout the profile. Presence of a gravel layer consist of quartz and feldspar gravel could be seen in the subsurface soil. Different to Aluthwewa series due to small sizes of feldsphar gravel found. Medium available soil moisture content and therefore susceptible to drought condition. Susceptible to soil erosion and should not expose the surface during the rainy season. Low OM content, but good in available nutrient. Homesteads and upland annual crops.
IBL, This is well drained moderately shallow to moderately deep soil. Occurrence of the soil is confined to crest and upper slopes of the undulating plain around Karuwalagawewa in Anamaduwa area. Texture of the soil is gravelly sandy loam. Medium available soil moisture content and therefore susceptible to drought condition. Susceptible to soil erosion and should not expose the surface during the rainy season. Low OM content, but good in available nutrient. Shrub jungle and homestead gardens.
RBE, This is a deep, well drained soil in undulating. Texture of the surface soil is loam due to presence of gravel layer. Gravel content increases with the soil depth. Low available soil moisture content and therefore very susceptible to drought condition. Susceptible to soil erosion and should not expose the surface during rainy season. Low OM content, but good in available nutrient. Upland annuals/ Homestead.
RBE, This is a deep well drained soil in undulating terrain. Texture is gravelly sandy loam to gravelly sandy clay loam. Hard due to presence of gavel and it is a main barrier for cultivation. low available soil moisture content and therefore susceptible to drought condition. Susceptible to soil erosion and should not expose the surface. Low OM content and medium available nutrient. Upland annuals/ Homestead gardens.
RBE, This is a well drained soil derived from quartz rich parent material. This soil series occurs on the crest, upper slope and mid slope physiographic positions within undulating and rolling landforms north of Dambulla-Grithale towards Trincomalee. Depth of soil varies according to the physiographic position of the landform. On hilly terrain, surface soil is eroded and quarts rich subsurface soil is present as a surface layer. Size of quartz fraction and the amountlocation. Texture and structure of the subsurface soil is gravelly sandy loam. Very low available soil moisture content and therefore very susceptible to drought condition. Susceptible to soil erosion and should not expose the surface. Low OM content, but good in available nutrient.Shrub jungle/ Teak plantations.
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IBL, This is a well drained; moderately shallow to moderately deep soil occurs mainly on crest physiographic position of the undulating terrain of Polonnaruwa, Kaduruwela, Hingurakggoda area. Surface soil is sandy clay loam texture. Low available soil moisture content and therefore susceptible to drought condition. Susceptible to soil erosion and should not expose the surface during rainy season. Low OM content, but good in available nutrient. Upland annual crops.
NCB, This is a moderately deep, moderately well drained soil confined to the east of Mahaweli river around Welikanda, Surface soil is sand to loamy sand texture. Very low available soil moisture content and therefore very susceptible to drought condition. But shallow water table and perch water table during rainy season make soil poorly drain condition. Susceptible to soil erosion and should not expose the surface. Low OM content and available nutrient. Soil is slightly acidic. Homestead/ upland annual crops.
Rendzena (1961 classification) Undulating, Moderately well drained loam to loamy sand soil, low available soil moisture content and therefore susceptible to drought condition. Very susceptible to soil erosion and should not expose the surface. Low OM content and available nutrient. Ca accumulation in sub surface and a potentially saline soil. Shrub jungle.
IBL, Aranthalawa series consist of moderately deep, well drained, loamy sandy to sandy loam soil. Exposed rocks on the land surface are very common within the soil. Low available soil moisture content and therefore very susceptible to drought condition. Susceptible to soil erosion and should not expose the surface. Low OM content and available nutrient. Homesteads, upland annuals; Teak plantations.
IBL, Hingurana series occurs on the crest physiographic positions of the undulating landform in Hingurana area of Ampara district. It is a well drained, moderately shallow to moderately deep, soil Texture of the soil varies from loamy sand to loam. Very low available soil moisture content and therefore very susceptible to drought condition. Susceptible to soil erosion and should not expose the surface. Low OM content and available nutrients. Sugar cane, homestead gardens, shrub jungle.
RBE, This is a deep, well drained soil in undulating terrain. Surface soil is sandy loam to sandy loam soil. Decomposing quartz gravel could be seen within the subsurface soil. Very hard soil. Very low available soil moisture content and therefore very susceptible to drought condition. Susceptible to soil erosion and should not expose the surface. Low OM content, but good in available nutrient. Shifting cultivation.
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RBE, Walawe series occurs on crest, upper and mid lower slope physiographic positions of the undulating terrain within DL1b zone. Surface soil is sandy clay loam. Medium available soil moisture content and therefore susceptible to drought condition. Susceptible to soil erosion and should not expose the surface. Low OM content, but good in available nutrient. Upland annuals/ homesteads/ Sugar Cane.
RBE, This is a deep, well drained soil occuring within undulating terrain in the eastern part of DL1b zone. Surface soil is sandy loam. Surface soil is eroded in most of the locations. Well drained. Low available soil moisture content and therefore susceptible to drought condition. Susceptible to soil erosion and should not expose the surface. Low OM content, but good in available nutrient. Homestead/ Upland annuals.
RBE, This is a deep, well drained soil occurring within Undulating terrain in DL1b and DL5 agro ecological zones. Surface soil is eroded, clay loam texture and very hard when dry. A layer of quartz gravel could be seen within the subsurface soil. Medium available soil moisture content and therefore susceptible to drought condition. Susceptible to soil erosion and should not expose the surface. Low OM content, but good in available nutrient. Upland annuals/ shrub jungle.
RBE, a deep, well drained soil occurring within undulating terrain adjacent to the coastal zone. Structure of the soil is varies from sandy loam to sandy clay with the increase of soil depth. Presence of ironstone gravel throughout the profile is a marked feature of this soil. High clay content, Low available soil moisture content and therefore very susceptible to drought condition. Low OM content, but good in available nutrient. Shrub jungle/ upland annuals/ homesteads.
ULHITIYA SERIES (Dry zone sub group)
RBE, This is a well drained, deep soil which occurs within IL2 agro-ecological zone around Mahiynganaya. Presence of gravel layer consisted of quartz and feldspar is an identical feature of this soil. Texture of the soil varies from sandy loam to sandy clay. Medium available soil moisture content and therefore susceptible to drought condition. Susceptible to soil erosion and should not expose the surface. Low OM content and poor in available nutrient. Home gardens and upland annuals.
RBE, imperfectly drained soil occurring adjacent to Ranorawa series on lower slopes of the undulating terrain. Texture of the surface and subsurface soil is sandy clay loam. Medium available soil moisture content and therefore susceptible to drought condition. Low OM content, but good in available nutrient. Grown upland annual crops or irrigated paddy.
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RBE. This is a moderately deep to deep, imperfectly drained soil which occurs on the middle and lower physiographic positions of the undulating terrain adjacent to Aluthwewa series. Located in north of Dambulla within the dry zone. Texture of the soil is sandy clay loam throughout the profile, Medium available soil moisture content and therefore susceptible to drought condition. Susceptible to soil erosion and should not expose the surface. Low OM content and available nutrient. Grown upland annuals/ shrub jungle.
RBE, a deep and imperfectly drained in Undulating terrain. Texture is clay loam to sandy clay loam. Medium available soil moisture content and therefore susceptible to drought condition. Susceptible to soil erosion and should not expose the surface. Low OM content and available nutrient. Upland annuals/ Shrub jungle.
NCB, This is a moderately deep, imperfectly drained soil occurring in undulating terrain adjacent to the Welikanda series. Slightly acidic soil. Very low CEC. Sandy texture and very low available water and therefore water stress can occur during the dry period. Susceptible to soil erosion and should not expose the surface. Low OM content and available nutrient. Grasses and upland crops are grown.
MAHAGAL ARA SERIES
RBE, Mahagal ara series is a deep, imperfectly drained soil in undulating terrain. Sandy loam in texture, Presence of mottles in the subsurface soil is due to fluctuation of ground water table is a marked feature. Low available soil moisture content and therefore susceptible to drought condition. Susceptible to soil erosion and should not expose the surface. Low OM content and available nutrient. Homestead, upland annuals, shrub jungle.
LHG, Hurathgama series is deep and poorly drained soil in flat terrain, Texture is sandy clay loam throughout the profile.CaCO3 depositions are present in the subsurface soil as concretions and a potential saline soil. Medium available soil moisture content. Low OM content and available nutrient. Irrigated Paddy.
LHG,This is a deep, poorly drained soil occurring within valley bottoms of the undulating to rolling terrain east of Kahatagasdegiliya towards, Trincomalee. Sandy loam texture. Low available soil moisture content and therefore susceptible to drought condition. Low OM content and available nutrient. High sodium content in soil. Used for Irrigated paddy.
LHG, This is a deep, poorly drained soil occurring in association with Welikanda, Mutugala, and Aralaganwila area on valleys of the undulating topography. Sandy clay loam, Top soil is slightly acidic. Medium available soil moisture content and therefore susceptible to drought condition. Low OM content and available nutrient. used for Irrigated paddy.
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Solodized Solonetz, Sevenagala series occurs on valley bottoms and depressions of the undulating terrain within DL1b and DL5 zones and a poorly drained soil. Sandy clay loam, Accumulation of calcium carbonate below 60 cm from the surface is very common within this soil. High in Mg, Ca and Na in soil. Sub surface soil is alkaline and high in EC. Therefore, saline or potentially alkaline soil. Grasslands/ Sugar Cane cultivation.
Solodized Solonetz, poorly drained deep soil occurring on valley bottoms and depressions. Texture of the soil ranges from sandy loam to sandy. High in Mg, Ca and Na in soil particularly presence of high content of sodium salts cause salinity. Used for rice cultivation, abandoned rice fields or grasslands.
KUDA OYA SERIES (Dry zone sub group)
LHG, a deep, poorly to very poorly drained and glayed soil in flat terrain. Texture of the surface soil vary from loamy sand to sandy loam Low available soil moisture content and therefore susceptible to drought condition. Low OM content and available nutrient. irrigated or rainfed paddy.
KATAGAL ARA SERIES
LHG, Poorly drained deep soil occurring in flat terrain within DL1b agro-ecological region. sandy clay loam texture. Accumulation of calcium carbonate is visible on the surface soil and within lower part of subsurface soil. Medium available water and therefore susceptible to drought. Slightly saline soil. Irrigated paddy.
IBL, The soils of initially a well drained soil. Due to continuous cultivation of rice with irrigation on flat terrain tends to develop a poorly drain condition. Presence of 10 cm thick pale brown bleached compact sandy layer which is similar to E horizon is a marked characteristic of this soil. Sub surface soil is High in Na and slightly saline and alkaline. Low moisture and available nutrient. used for irrigated paddy.
LHG, a poorly drained, deep, soil in flat terrain. Texture throughout the profile is loamy sand to sandy loam. Very low available water and nutrient content. Top soil is slightly acidic. Soil is slightly saline. Used for irrigated paddy.
NEGAMBO SERIES (Dry zone sub group)
Regosol, The soils of the Negambo series are located along the beach of the wet zone of the low country. These soils have been derived marine sand deposits. These soils are deep, excessively well drained, structure less and sandy in texture, Flat (0-1% slope) terrain. Very low available nutrient and moisture content. But moisture is sufficient for deep rooted crops. Coconut and onion cultivation.
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Regosol, This soil is derived from recent marine sand deposits and occurs close to the sea coast. Deep and excessively well drained soil in flat terrain. Water table is generally 2 meters below the land surface. Very low available moisture and nutrient content. Due to sandy nature of the soil and upland annual and fruit crops and coconut are the prominent land uses on this soil.
Red Latosols, Excessively well drained soil in undulating sand to sandy clay loam. Very low available moisture and nutrients. Coconut plantations.
Red Latosols Willpattu series is a deep, excessively well drained soil in undulating terrain. Texture varies from sand to sandy clay loam. Clay content increases with depth. Very low CEC, soil available soil moisture and available nutrient content. Coconut plantations/ Homesteads.
Regosols,This is a deep, excessively well drained soil derived from old marine sand dunes. This soil occurs to the flat terrain of sea coast north of Trincomalee paralal to sea coast. Texture of the soil is sandy. Slightly alkaline and saline. Very high Ca and Na in the soil. Very low CEC, OM content and available nutrient. Coconut and vegetables.
Regosols This is a deep moderately well drained soil found in flat terrain derived from old marine sand deposits. Texture of the soil is sandy throughout the soil profile. Depth to ground water table is between 60-90cm, but during dry season it is about 3m below the land surface. Very low available water content and available nutrients and OM content. Homesteads with coconut and cashew.
Yellow Latosols This is a deep, imperfectly drained soil derived from old sandy marine deposits which occurs on lower slopes of the undulating terrain. Texture of the soil is sandy throughout the soil profile. During dry season ground water table is about 4 meters below the land surface. Use for Coconut.
Yellow Latosols Deep imperfectly drained soil occurring in undulating terrain adjacent to the Gambura series on the lower terrace. Surface soil is texture with sandy clay loam to clay loam texture. Clay content in the soil increases with the soil depth. Very low available water content and available nutrients and OM content. Coconut Plantation.
Soldized Solonetz, This is a very poorly drained, moderately deep soil occuring on the depressions in the coastal lagoon and derived from marine sediment deposits. During high tide this soil will be under submerged condition. Texture of the soil varies from
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sandy clay to sandy loam. High in soil Mg and Na content. a saline soil and very low available water content and available nutrients and OM content Grasses.
Regosols This is a deep poorly drained soil derived from old marine sandy deposits and found in the lower slope of undulating terrain. Texture of the soil is sandy throughout the soil profile. During the rainy season the depth to the ground water table is between 50cm. Salinity/ sodicity could be expected on depressions. Very low available water content and available nutrients and OM content. Rainfed paddy.
Soladized solonatez Flat, Very poorly drained, deep soil. sandy loam texture, Accumulation of calcium/ magnesium carbonates as concretions or white colour powder and higher sodium adsorption ratio in the soil are common features of this soil is sodicity/ salinity. Shrub jungle/ abandoned paddy.
HEBARAWA SERIES (Dry zone sub group)
Alluvial soil, well drained, deep soil which occurs along the levee of the Mahaweli river. Flat terrain, Texture of the soil varies from sandy loam to clay loam. Medium available moisture and nutrients content. used for upland annual crops, brick production.
Alluvial Soils This is a deep, well drained soil occurring flat terrain on the levee of Weli Oya and Walawe rivers. sandy loam to sandy clay loam texture. Low in available soil moisture and nutrient content. Use for upland annual crops.
Alluvial Soils Moderately well drained soil occurring on the back slope of the flat terrain in the Mahaweli river flood plain. loam texture, Low in available soil moisture and nutrient content. Shrub jungle/ Natural reservation, Flooding is a problem.
GAL OYA SERIES
Alluvial soils, Gal Oya series consist of deep, moderately well drained soil, occurring in the flat terrain on levee of the Gal Oya. Texture of the soil ranges from loamy sand, sandy clay loam to clay loam. Irrigated Sugar Cane, shrub jungle, homestead gardens.
MUTHUKANDIYA SERIES (Dry zone sub group)
Alluvial soils, Poorly drained soil found in the flat terrain, Texture of the soil varies from sandy to sandy loam. Low in available soil moisture and nutrient content. Very high infiltration rate and need lot of water. Rainfed or irrigated paddy.
Grumusols, Pallegama series occurs on the back slope of the Walawe river flood plain. This is a deep, very poorly drained soil. Formation of cracks during dry season
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is a marked feature of this soil. Very high in available water. Very hard when dry and sticky when wet. Deposition of calcium and magnesium carbonate in the sub surface soil. Irrigated paddy.
Alluvial soils Aruvi series is a poorly drained deep soil derived from alluvial deposition and found in flat terrain. Clay alluvial deposition and high in available water. Slightly saline. Shrub jungle.
Soil series in the Iintermediate zone MADAMPE SERIES
Regosols, Imperfectly drained loamy sand to sandy loam texture. Low available water and high infiltration. Therefore, need frequent irrigation, if other crops are grown. Poor in available nutrient and O.M. content. coconut cultivation and home garden.
Alluvial soil, Deep imperfectly drained soil derived from alluviam of Deduru Oya. Texture is loamy sand, Dering the rainy season develop shallow (50cm) ground water table.Very low available water, nutrient and OM content.Acidic reaction.Coconut plantations, Home garden fruits.
Alluvial soil, Deep imperfectly drained. Sandy loam to sandy in texture. Very low available moisture and high infiltration. Therefore, need frequent irrigation if other crops are grown. Low available nutrient and O.M. content. Coconut cultivation.
RYP, Moderatly deep well drained. Sandy in texture, very low available water and nutrients. Presence of plinthite is a problem. Used for coconut cultivation.
RYP, Deep imperfectly to poorly drained soil in undulating terrain. Sandy in texture, Very low available moisture and nutrients. Used for coconut cultivation.
RYP, Deep well drained soil in undulating to rolling landform. Gravelly and sandy in texture. Medium available moisture. Temporary water table during rainy season. Poor in available nutrients and O.M. content. Coconut cultivation.
RYP, Well drained soil in undulating to rolling terrain with sandy clay loam to clay loam texture. Medium in available moisture and low in available nutrient and OM. Slightly acidic in reaction. Coconut and mixed crops.
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RYP, Deep imperfectly to poorly drained soil in undulating terrain Sandy loam texture Fluctuating water table and during rainy season ground water table is very close to surface. Moderately available soil moisture. Therefore, water stress during dry spell. Poor in available nutrients and O.M. content. Coconut cultivation.
LHG, Deep poorly drin soil occurring in the broad vallies of IL1. Texture is sandy clay loam to clay loam. Good available moisture. No moisture stress. Poor in available nutrient and O.M. content. Paddy cultivation both Yala and maha.
RBE, Well drained soil found in crest and upper and middle slope of the undulating terrain in IL3. Gravelly sandy clay loams texture. Low in available moisture and poor in available nutrient and O.M. content. drought prone soil. Shrubs and shifting cultivation.
NCB, Deep imperfectly drained soil in undulating terrain. Sandy in texture, low available water drought prone and needs irrigation. Poor in nutrient content and O.M. Prone to soil erosion. Coconut, rice, mixed cropping.
LHG, Deep very poorly drain with clay loam texture in valley bottoms of IL3. Medium in available moisture and available nutrient content and low in O.M. Accumulation of CaCO3 in subsurface and a potentially saline prone. Paddy cultivation.
IBE Deep well drained sandy clay loam texture soil in Rolling to hilly terrain. Sandy clay loam to clay loam texture. Low in available moisture and available nutrients content and OM. Somewhat, drought prone during dry spell. Erosion prone. Coconut, and home garden.
IBL, Shallow to medium deep well drained soil in upper and middle slope of rolling terrain. Sandy in texture, low available moisture, drought prone. Good in available nutrient and OM content. Erosion prone. Mixed crops Kandian home garden.
RBL, Deep well drain soil in middle slope of rolling terrain. Clay loam textured. Good in available moisture. Low in available nutrients and O.M. content. Erosion prone. Mixed crops Kandian home garden.
Randzinas, Moderately shallow well drained soil in steeply dissected (> 30%) terrain mainly in IM3. Clay loam texture Alkaline reaction subsurface soil due to
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decomposing CaCO3. Very low in available moisture and drought prone. Erosion prone. Good in available nutrient Abandoned and home garden or vegetable cultivation.
IBL, Shallow well drained soil in hilly to steeply dissected terrain. Loamy sand to sandy clay loam texture. Decomposing parent material in the sub surface. Erosion prone. Low in available water and good in nutrients, but poor in OM. Vegetable and mixed crop.
RYP, Shallow, well drained soil in steeply dissected to mountain terrain. Gravelly, sandy clay loam to clay loam texture. Erosion prone. Low in available moisture, drought prone. Barron/ Abandoned lands.
RBL, Very deep well drained soil in steeply (< 30%) dissected to mountain terrain. Clay loam textured, medium in available water Good in available nutrients, but low in OM. Erosion prone. Vegetable mixed crop, Tea cultivation.
RYP, Deep well drained soil in steeply dissected to mountain terrain. Clay loam in texture. Good in available water and available nutrient content and OM. Acidic in reaction. Tea, home garden and mixed cultivation.
IBL, Moderately shallow, well drained soil in hilly to steeply dissected terrain. Sandy clay loam texture. Moderately available water and good in available nutrients. Poor in OM content. Erosion prone. Acidic in reaction. Vegetable and home garden.
RYP, Deep well drained soil in rolling to hilly terrain. Clay loam in texture with somewhat gravelly. Good available water content and poor in nutrient content and OM. Erosion prone. Acidic reaction. Tea, Vegetable cultivation.
RYP, Moderately deep well drained soil in hilly (>30%) to steeply dissected landform. Sandy clay loam in texture, poor in available moisture, moderate in available nutrients and OM. content. Erosion prone. Tea and forest.
RBE, Moderately deep well drained soil in rolling terrain. Sandy clay loam to gravelly clay loam in texture. Moderately available water content, drought prone, poor in available nutrients and OM content. Home garden.
Alluvial, Deep well drained soil in flat terrain of the levee of the Mahaweli bank. Sandy to sandy loam texture. Low available moisture, drought and erosion prone, good in
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available nutrient low in OM. upland annual crops.
KUDA OYA SERIES
LHG, Deep poorly drain soil in flat terrain. Loamy sand to sandy loam texture. Moderately available moisture and nutrients. Low in OM. Irrigated and rainfed paddy.
IBL, Moderately deep well drained, loamy sand to sandy loam soil in undulating to rolling terrain. sandy loam to loamy sand in texture, low available water, drought prone. Erosions prone. Moderately available nutrient and low OM. content. home garden and spices.
Alluvial, Deep poorly drained soil in flat terrain. Loamy sand texture. Moderately available water content and good available nutrient. Low OM. Rainfed or irrigated paddy.
IBL, Deep moderately well drained soil in undulating terrain. Loamy sand and moderately available water. Susceptible drought. Good in available nutrient and low in OM. Home garden and sugarcane cultivation.
Lithosols, Shallow, well drained soil in hilly (< 30%) to steeply dissected landform. Sandy loam texture. Erosion prone. Moderately available water and poor in nutrients and O.M. content. abandoned lands.
RYP, Deep well drained soil in (< 30%) to steeply dissected landform. Erosion prone. Somewhat gravelly to Gravelly clay loam texture. Poor water holding capacity and available moisture, drought prone, low in available nutrients and OM. Abandoned Tea cultivation.
IBL, Shallow well drained, hilly (< 30%) to steeply dissected landform. Prone to erosion. Sandy loam texture. moderately available moisture. Good in available nutrient, but poor in OM. Home garden.
IBL Moderately deep well drained soil in rolling to hilly landform. Prone to soil erosion, sandy clay loam texture, low in available water and nutrients. Poor in OM. Abandoned scrub jungle.
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RBL, Deep well drained soil occurring in valleys of undulating to rolling terrain. Clay loam texture, Moderately available moisture. Poor in nutrient content and OM. home garden with mixed crops.
RYP, Deep well drained soil with hard laterite in undulating terrain. Sandy loam texture. Low available water content and poor in available nutrients and OM. Home garden and coconut cultivation.
Soil series in the Wet Zone MAWANELLA SERIES
IBL, Shallow, well drained soil in hilly (16-30%) landform. Gravelly sandy clay loam texture, moderately available moisture and good in available nutrients. Low in OM. no water stress Acidic in reaction. Mainly rubber plantations.
Red Latasol, Deep, excessive well drained soils in undulating terrain in elevated coastal ridges, Sandy in texture, low available moisture and therefore, have moisture stress. High infiltration rate and need frequent irrigation. Acidic reaction and very available nutrients and OM. Mixed cropping.
RYP, Moderately deep well drained soil in undulating to rolling terrain. Sandy clay loam texture, low in available water and high infiltration rate. Less water retention and susceptible for drought Acidic in reaction and low available nutrient. Mainly use for rubber and home garden.
RYP, Shallow, well drained Gravelly sandy clay loam soils in hilly to mountain landform. Very high gravel content (40-50%) in the soil. Low available water but good in available nutrient. Low OM. Drought stress, Acidic in reaction, Homestead, mixed crops, Tea.
RBL, Deep, well drained, sandy clay loam texture soil in crest, mid and lower slope of rolling to hilly landform. Medium water holding capacity. Medium infiltration rate low moisture stress. Acidic reaction, low available nutrient and OM. Kandian forest garden.
RYP, Deep well drained soil of sandy clay loam texture found in crest, mid and lower slope of hilly to steeply dissected landform. Medium available water, but less moisture stress. Low available minerals and O.M. content. used in rubber cultivation and mixed crop.
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LHG, Deep, very poorly drained clay loam soil occurred in valley bottoms of undulating to rolling terrain. Very good available water content and shallow water table. Medium available nutrient content and low OM. Acidic in reaction, Ion toxicity in fields near to upland. Rainfed rice cultivation.
Alluvial soil, Deep, well to moderately well drain soil with clay loam in flat terrain. Very good available moisture content. No water stress. Low in available nutrient and OM content. AciDIc in reaction. Rubber, Vegetable cultivation.
Regosols, Very deep moderately well drained loamy sand soil in a flat terrain. Very low available moisture and possible moisture stress for shallow rooted crops. Very low available nutrients, CEC and OM. Coconut and home garden.
LHG, Deep Very poorly drained soil in valley bottoms of rolling terrain of Boralu series. Clay loam to clay and in WL3 and WL4. Medium available moisture, low in available nutrients but good in OM content. Acidic in reaction and iron toxicity. Rainfed paddy.
RYP, Moderately deep well drained soil in hilly to steeply dissected landform. Soils are highly acidic in reaction and gravelly (2mm and >50%) sandy clay loam. Very low available moisture, drought prone. Low available nutrient and O.M. content. rubber cultivation.
RYP, Deep well drained gravelly sandy clay loam in upper slope of the undulating terrain. Low available moisture and nutrients. Drought prone. Acidic reaction and low O.M. content. Coconut and mixed crops.
RYP, Deep well drained gravelly sandy clay loam soil in crest of the undulating terrain. Very low available water and drought prone. Low in available nutrients and OM content. Acidic reaction. rubber cultivation.
RYP, Deep moderately well drained gravelly sandy clay loam soil in midslope of undulating to rolling terrain. Very low available moisture and drought prone. Poor in available nutrients and OM content. Acidic reaction and used for rubber and mixed crop.
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Half Bog, Deep soil with very poorly drained condition in low lying areas of coastal plain and depression in undulating, rolling and hilly terrain. Acidic reaction sulphour accumulation in lower horizon. Very high in clay and O.M. flooding during rainy season. Rainfed rice and natural grasses.
RYP, Deep well drained soil in hilly steeply (25â&#x20AC;&#x201C;55%) dissected landform. Sandyclay loam to clay loam in texture and very low in available moisture, drought prone. Low available nutrient. Acidic reaction. Mixed crops, Tea and home gardening.
Alluvial, Deep well drained soil in flat terrain in Mahaweli flood plain. Sandy clay loam to clay. High available water content. Poor in available nutrient and OM content. Acidic in reaction. paddy during maha and vegetable during yala.
Bog soil, Deep poorly drained soil in low lying areas of coastal plain of Low country. Accumulation of S and a acid sulphate condition. Very high in clay content and high available water content. High in OM and low available nutrient. Abandoned/ rice.
RYP, Deep well drained clay loam soil in hilly to steeply dissected landform in Hatton and Talawakele area. Good in available water, no moisture stress. Good in available nutrient and O.M. content. Acidic reaction. Tea cultivation.
RYP, Shallow well drained to moderately drained soil with high OM in top soil. Loamy texture and the soils found in flat terrain ih the hilly mountain area. Medium in clay high OM and available moisture. Acidic in reaction, abandoned and grass.
NUWARA ELIYA SERIES
RYP, Deep moderately well drained soil in hilly to steeply dissected landform. Top soil high in OM and sandy clay loam. Erosion pron. High in clay content and available water content vegetable cultivation.
RYP, Moderately deep, well drained soil in hilly to mountains landform, in the WU1. Sandy clay loam and prone to soil erosion. Low available water and drought prone. Good in available nutrient and OM content. Acidic in reaction. Tea cultivation.
RYP, Deep well drained soil with high OM in top soil in steeply sissected to mountains reagion of Sinharaja forest area. Gravelly loam soil. Low available moisture content, Acidic reaction. Good in O.M. and available nutrient. Coconut, rubber, Tea and mixed cultivation.
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RBL, Very deep well drained clay loam soil on mid and lower slope of undulating to hilly terrain. soil erosion, Good available moisture content. Poor in available nutrient and OM content. Acidic in reaction, mixed crops.
RBL, moderately deep well drained gravelly sandy clay loam soil in hilly to concave upper slope. Prone to soil erosion, good available moisture content poor in available nutrients and OM content. Acidic in reaction. mixed crops.
IBL, Moderately deep well drained soil with sandy clay loam texture. Occurs on the hill and rounded landscape. Prone to soil erosion. High in available nutrient, low in available water, low in OM and slightly acidic in reaction. Kandian forest garden.
Bog soils, Poorly drained soil. High in OM, soils are saline sodic. Potential acid sulphate soils. Mangrove or abandoned, flooding hazards.
Regosols Deep excessively well drained sandy texture. Very low available moisture and nutrient content, low OM. coconut cultivation.
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