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Undercover

farming

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JULY/AUGUST 2021

I Volume 18 No 4 I  I R45.00 per issue

Healthy Seedlings

Climate Control

Horticultural cluster

Aquaculture: Purging Fish

Moorland Seedlings Nursery Page 4

Greenhouse Climate Control and Sustainable Energy Use Page 10

Solution for Sectoral Growth and Food Security Page 14

Aquaculture Techniques: Purging Fish Page 16


ucf

Undercover

farm

greenhouses I shade net I hydroponics I aquaponics

JULY/AUGUST 2021

I VoLUme 18 No 4 I  I R45.00 per issue

PROPRIETOR I ADVERTISING SUZANNE OOSTHUIZEN 082 832 1604 suzanne@axxess.co.za EDITORIAL CONTENT & COMPILATION Johan Swiegers 082 882 7023 editors@axxess.co.za ADDRESS PO Box 759, Montana Park 0159 E-MAIL magazine@axxess.co.za FAX 086 518 3430 DESIGN Fréda Prinsloo PRINTING Business Print Centre DISCLAIMER Undercover Farming accepts no responsibility for claims made in advertisements or for opinions and recommendations expressed by individuals or any other body or organisation in articles published in Undercover Farming. COPYRIGHT Copyright is reserved and the content may only be reproduced with the consent of the Editor.

Contents 4

Moorland Seedlings Nursery – Expect Quality and Healthy Seedlings

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Hydroponics System Advice: Removing Unwanted Ions from Water

8 Preventing seedling damping off 10 Driving Forces for Greenhouse Climate Control

FRONT PAGE: Rian Moore, Managing Director of Moorland Seedlings, inside one of the greenhouses. HeALTHY SeedLiNGS

cLimATe coNTRoL

HoRTicULTURAL cLUSTeR

AqUAcULTURe: PURGiNG FiSH

moorland Seedlings Nursery Page 4

Greenhouse climate control and Sustainable energy Use Page 10

Solution for Sectoral Growth and Food Security Page 14

Aquaculture Techniques: Purging Fish Page 16

INSIDE ...

and Sustainable Energy Use

12 Haifa Chemicals is Pioneering the Future of Calcium Nitrate Nutrigation™

14 A Horticultural Cluster – Solution for Sectoral Growth and Food Security

16 19 19

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Aquaculture techniques: Purging Fish Prokon welcomes Supreme Court Ruling Subscription form

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SUBSCRIBE Obtain your Undercover Farming magazine digitally! Online subscription Subscribe online now! E-mail your deposit and address details to: magazine@axxess.co.za More information from Suzannne Oosthuizen: 082 832 1604 See subscription form on page 16 visit us at • besoek ons by

The Scriptures

DRAW NEAR TO HIM! Psalms 73:27,28 For indeed, those who are far from You shall perish, You have destroyed all those who desert You for harlotry. But it is good for me to draw near to God; I have put my trust in the Lord God, that I may declare all Your works.

Subscription details on p19

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hile the Covid pandemic is still on hand and many people are lost because of this, it is imperative that the horticultural sector should hold its own and carry on producing. It is generally accepted that vegetables on the plate is a must for healthy living. Our greenhouse farmers who are foremost in producing healthy greens, tomatoes, peppers and more for our daily consumption, have to contend with all the rules and regulations of Covid over and above the good agricultural practices they are held to by larger retail chains. It must be like playing a lot of balls at once with only one club. Hats off to our undercover farming producers who keep on producing through it all! The strength in farming strategy lays in sound management, to be alert for the unforeseen (like a pandemic, sudden climate change for the worse) and more. Many farmers are in serious debt because they expanded too much, too rapidly. However, those who kept tight watch over their demand, market tendencies and forward planning, are secure in their businesses and South Africans may rest in peace as there is little doubt that the country will be without food. We saw the sudden piling up of domestic food stocks after electronic scaremongers got online since March 2020, but still, even though sometimes a few outlets ran low on stocks, within a day or two the shelves were full again. The undercover farming industry in South Africa grew fast over the past 20 years or so, and certainly there are financial and other constraints they have to bear with, therefore we saw less new greenhouse farmers coming to the fore, but the steadfast ones increased their production, added on to their greenhouses and widened their marketing scope. The shade net farmers and particularly the pomological fruit, citrus, table grapes and blue berry producers are doing exceedingly well; by looking at the many new shade net structures going up in these particular agricultural areas in South Africa. Keep up the good work and keep undercover farming in SA strong and healthy!

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Moorland Seedlings Nursery –

Expect Quality and Healthy Seedlings

Petunia seedlings grown for Garden Supply centres. The enormous greenhouse complex of Moorland Seedlings near Jeffreys Bay.

As long as food security remains important, a seedling nursery will remain important. The two most serious situations South Africa is faced with are the poor standing of the economy and the Covid-19 pandemic which places even more pressure on the economy.

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ovid-19, ironically, under­ scored the importance of food security and agriculture. The all-importance of Agriculture as an essential service per se, was highlighted during all levels of restrictions on movement during the pandemic. This again emphasized the importance of food production to the nation. The supply of affordable and quality seedlings is the foundation of trustworthy

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food production by appropriate producers in the different sectors. As far as citrus is concerned, the exports and the earnings of foreign currency and the importance of this to the South African economy, featured much stronger. For these reasons Rian Moore, Managing Director of Moorland Seedlings is convinced of their ongoing, all-important role being part of the Seedling Growers South Africa industry. Moorland Seedlings supply mostly to producers in South Africa. Seedlings grown at Moorland Seedlings are mostly (about 90%) for open land farmers. Around eighty million seedlings are grown by Moorland Seedlings per annum. Under the leadership of Rian Moore, Moorland Seedlings was started as

a small nursery in 1997 but has progressed to become a major role player in the seedling industry in South Africa today. Moorland Seedlings produces the full spectrum of vegetable seedlings, including production of carrot and onion seedlings for seed production. Tobacco seedlings are also produced for the Eastern and Southern Cape Regions. This important seedling grower in the South Eastern Cape also grows citrus trees for different Provinces. Moorland Seedlings does business with any registered seed supplier which meets the right requirements. Vegetable or greens producers may suggest which seed they would like seedlings to be grown from, but practically speaking, larger growers are beforehand consulted over their requirements for specific seed, for specific production requirements and of course, that of their market. Behind the curtain (in a matter of speaking) Production Protocols are followed most strictly. Management holds

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tight control over this process. Each role player at the Moorland Seedlings Nursery has an important work, therefore dedication and responsible work attitude is of essence. These qualities must be inherent in each worker at Moorland Seedlings nursery. There are seasonal patterns of seedling growing in different sections of the production unit. Moorland Seedlings services a diverse market which includes vegetables, flowers and fruit. Practically, they grow seedlings year-round. Seed companies prefer to execute trials on new seed varieties on own Trial plots where synchronized plantings are done. The organize Information Open Days to show producers results of new varieties. Seedling growers are being invited as well and are able to advise clients accordingly.

Rijk Zwaan, a prominent seed supplier with a wide farmer support system in Africa, has Moorland Seedlings grow their Sweet Palermo pepper seedlings for producers in South Africa. This relatively new product requires the technical and precision seedling growing that Moorland Seedlings is known for. The Covid-19 pandemic caused serious effect on seed imports.

Assistants loading young citrus trees in a truck at Moorland Seedlings.

Fruit trees grown by Moorland Seedlings.

Rian Moore, Managing Director of Moorland Seedlings.

Currently, many parts of the Eastern Cape experience severe drought. The Kouga dam (128,7m2 capacity) has only 4.6% water. Production costs escalated abnormally an especially grow media import costs because of shortage of marine freight. Diversification helps to solve the problem, but it is not possible for all producers. In conclusion, seedlings grown by an expert remain the most cost effective way of growing vegetables, flowers, fruit and greens by an undercover farmer. The high seed price of good quality seed, the labour intensiveness and the precision to grow seedling yourself, with the possibility of losing seedlings along the way, can be avoided. By calling an expert like Rian Moore or one of the Seedling Growers of South Africa members and order quality seedlings, permits the vegetable, greens, flower or fruit producer to devote his efforts on what he does best; focus on sustainable food production for the nation. JS

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Hydroponics System Advice:

Removing Unwanted Ions from Water High levels of soluble (ferrous) iron may be found in wells or boreholes from the mountainous areas of the Cape, along the Drakensberg, and a few other areas. This iron is in a reduced state (Fe2+).

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hen Fe-rich water is used for sprinkler irrigation, ferrous iron is oxidized to form an insoluble ferric iron Fe3+ and it may be visible as a brown-red substance on leaves and garden walls. Manganese (Mn) is also soluble in its reduced state and precipitates as insoluble MnO2 when oxidized. When using water with high Fe or Mn concentrations for drip irrigation, the ions are oxidized, and these insoluble salts block the drippers. Apart from oxidation due to aeration, ferric and manganese bacteria are chemotropic and contribute to oxidize Fe and Mn. These ferric and manganese bacteria cause the oxidized residues to accumulate among the bacterial waste, creating a slimy residue, also blocking drippers. Fe and Mn concentrations in water are important feeding water quality parameters in areas with high levels of these ions in the water. Good quality is regarded as safe to use, where Fe and Mn levels are <0.1 and <0.02 mg L-1, respectively. Medium quality water may contain Fe at 0.1 to 0.5 and Mn at 0.02 to 0.3 mg L-1. Poor quality water contains Fe at >0.5 or Mn at >0.3 mg L-1,

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needing pre-treatment to Table 6: The effect of pH on the aerobic oxidation times lower their concentrations for iron and manganese. (Netafim). where drippers are used. pH level Aerobic oxidation Aerobic oxidation By aerating feeding time for Fe time for Mn water, Fe and Mn can be (minutes) (minutes) oxidized. Small oxidized <6 >180 >1000 particles can then be 6.6 < 60 >1000 removed with filters. 7.2 < 10 >1000 The oxidizing process is 7.8 < 6.6 >1000 extremely slow in acidic 9.0 < 3 < 200 water. By increasing the pH of the water before Aerobic oxidation time for Fe (minutes) for Mn (minutes) aeration, the oxidation time can be reduced applied, using Fe-chelate. With production substantially, as illustrated in Table 6. systems, where drippers are not used, removal of Fe is not critically important. The oxidation of ferrous iron may also be Sodium, chloride and other unwanted ions accelerated with UV tubes, the addition Should Na+ and Cl- levels of chlorine gas (Cl2), Fe and Mn exceed the maximum ozone (O3) or peroxide limits as shown in Table (H2O2). Growers who concentrations in make use of drip irrigation water are important 19, it should not be used as feeding water. However, should remove as much feeding water it may be diluted with Fe as possible from the quality parameters rainwater or the ions can feeding water. According in areas with high be removed with reverse to Deckers (2002), the levels of these ions osmosis, an expensive water natural Fe content of feeding purification system. This water cannot be absorbed in the water. system removes all ions by plant roots and should (macro- and micronutrients) from the be considered as not available. Other water, although some boron (B) may slip nutrients in feeding water can be topped through the membranes. up, but the total Fe-need should be 8


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EXPERIENCES BY A RIJK ZWAAN SWEET PALERMO FARMER

ACCORDING TO HANDREY, the Sweet Palermo has more fruit per plant and is a vigorous grower. The plant density on the Sweet Palermo is the same as the standard green pepper. He grows three plants and nine stems per square meter. To the question of whether he had to make changes in his growing system to accommodate Sweet Palermo, he answered; “We made no changes in our growing system, the Sweet Palermo fitted well into the current system. Furthermore, our seedlings are grown by Moorland Seedlings who provides us with a good quality product.” Handrey explained that the Rijk Zwaan representative Schalk Kotze, the crop specialist James du Preez and the South African team are consistent in their service to support and aid him throughout the growing season of Sweet Palermo. “The team always encourages us, and they really became part of the family,” he commented. His greenhouses currently have 1 000 m2 under Sweet Palermo production and he is planning to expand as the market grows.

Schalk Kotze, Sales Representative Eastern Cape and Handrey du Plessis of Nocton Farm “Everything needs to work together; right from the breeders of the Sweet Palermo seeds, through to growing of the plants in order to obtain top-quality fruit for the consumer to enjoy. Rijk Zwaan’s team is always a call away and they support us with the best technical advice. Their pride in their product and passionate service to the producer is clear every time they visit the farm,” Handrey concluded. Rijk Zwaan South Africa (Pty) Ltd 36 Steyn Road, Riet Vallei Farm, 1739 Krugersdorp, South Africa info@rijkzwaan.co.za | www.rijkzwaan.co.za

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greenhouses I shade net I hydroponics I aquaponics Hydroponics System Advice

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This method of water purification creates a large percentage of saline wastewater which should be well-managed to prevent pollution of soil and rivers.

Ions associated with alkalinity The alkalinity level in saline feeding water is usually high, due to high levels of one or more of the following: CO3 2-, HCO3 - and OH-. In the presence of Ca2+ and Mg2+ and under high pH conditions, a whitish-grey deposit of Ca- and Mg-carbonate (lime) may form when this water is used in kettles and geysers. Gadgets to desalinise or to soften water may be suggested by some institutions, in suspension. This may allow the water but their claims should be tested by to be used with less damage to elements chemical analyses, before and after a of electric kettles and geysers. water treatment. An inline cylinder, Apart from the danger that Ca- and Mg known as ‘Protection against total carbonate particles may block drippers, hardness’ (PTH, 2019), exposes water these crystals will react with applied acids to a combination of during the acidifying special metals that Apart from the danger that Ca- process when may lower Ca-, Mg nutrient solutions are and Mg carbonate particles and bicarbonate mixed. Ca and Mg may block drippers, these levels due to the will then be released precipitation of these crystals will react with applied as ions. Thus, PTHions as insoluble Ca acids during the acidifying treated water is and Mg-carbonate process when nutrient not recommended crystals that remain for hydro­ponics solutions are mixed.

production systems but may soften water used for gardening or households. The alkalinity anions (CO3 2-, HCO3 - and OH-) can be replaced by nitrate, phosphate or sulphate, by adding nitric- or phosphoric-, or sulphuric acid respectively. With a very high total alkalinity, special procedures should be followed and provision should be made for the release of CO2-gas, and will be explained in following editions of Undercover Farming. By: Dr N J J Combrink ‘Nutrient Solutions Management’ Dept. Horticulture, Stellenbosch University.

Preventing seedling damping off

D

amping off by seedlings affects many vegetables and flowers. It is caused by a fungus or mould that thrives in cool, wet conditions and is most common in young seedlings. Often large sections or whole trays of seedlings are killed. It can cause root rot or crown rot in more mature plants. Research advice is to use sterilized pots or trays with good drainage and use clean, new potting soil to prevent damping off. Seedlings infected by damping off rarely survive to produce a vigorous plant. Effects of damping off in a seedling tray. Once plants have mature leaves and a well-developed root system, they are better able to naturally resist the fungus or mould that causes damping off. There is a critical period of growth between planting and maturity when special care needs to be taken to protect sensitive seedlings. Young leaves, roots and stems of newly emerged seedlings are highly susceptible to infection. Damping off pathogens can cause root rot or crown rot in mature plants. The fungi, Rhizoctonia spp. and Fusarium spp., along with the water mould Pythium spp. are most common pathogens responsible for damping off. Symptoms • Seedlings fail to emerge from the soil. • Cotyledons and seedling stems are water soaked, soft & mushy. • Seedling stems become water soaked and thin. • Young leaves wilt and turn green-grey to brown. • Roots are absent, stunted or have greyish-brown sunken spots. It is therefore better to invest in seedlings purchased from a professional seedling grower to ensure you obtain healthy, strong seedlings. Source: UME

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It’s all in the

EXTENDING OUR RANGE

In four suprisingly colours

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All greenhouse cultivation systems, regardless of geographic location, comprise fundamental climate control components; depending on their design and complexity, they provide more or less climate control, and condition to a varying degree plant growth and productivity.

Driving Forces for

Greenhouse Climate Control and Sustainable Energy Use

A

ir temperature – as well as solar radiation and air relative humidity – is one of the most important variables of the greenhouse climate that can be controlled. It conditions not only crop development and production but also energy requirements, which can account for up to 40 per cent of the total production costs. The majority of plants grown in greenhouses are warm-season species, adapted to average temperatures in the range 17–27°C, with approximate lower and upper limits of 10 and 35°C. If the average minimum outside temperature is < 10°C, the greenhouse is likely to

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require heating, humidity exceeds The challenge is to meet particularly at night. 95 per cent for long both needs: improved energy periods, particularly When the average maximum outside at night as this favours efficiency combined with temperature is an absolute reduction in the the rapid development < 27°C, ventilation overall energy consumption of fungus diseases such will prevent as Botrytis cinerea. The and related CO2 emissions of increased interest in excessive internal the greenhouse industry. temperatures during maintaining adequate the day; however, transpiration to if the average maximum temperature avoid problems associated with calcium is > 27–28°C, artificial cooling may be deficiency has resulted in humidity being necessary. expressed in terms of the vapour pressure deficit (VPD) or the moisture deficit, The maximum greenhouse temperature should not exceed 30–35°C for prolonged both of which are directly related to transpiration. periods. In temperate climates, heating Maintaining the VPD above a minimum and ventilation enable the temperature value helps to ensure adequate to be controlled throughout the year, transpiration and also reduces disease while at lower latitudes the daytime problems. During the day, humidity can temperatures are too high for ventilation usually be reduced using ventilation. to provide sufficient cooling during the However, at night, unless the greenhouse summer. Positive cooling is then required is heated, the internal and external to achieve suitable temperatures. The second important variable is humidity, temperatures may be similar; if the external humidity is high, reducing the traditionally expressed in terms of relative greenhouse humidity is not easy. humidity. Relative humidity within the range of 60–90 per cent has little 64 GAPs Because of the global rise in energy for greenhouse vegetable crops: Principles prices, greenhouse energy use became a major research issue. With the recent for Mediterranean climate areas effect increased interest in global warming and on plants. Values below 60 per cent may occur during ventilation in arid climates, or climate change, the use of fossil fuels is again on the political agenda and many when plants are young with small leaves, governments have set maximum CO2 and this can cause water stress. emission levels for various industries, Serious problems can occur if relative

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including the greenhouse sector. There are two main ways to increase greenhouse energy efficiency: to reduce the energy input into the greenhouse system; and to increase production per unit of energy. The challenge is to meet both needs: improved energy efficiency combined with an absolute reduction in the overall energy consumption and related CO2 emissions of the greenhouse industry. Technological innovations must focus on energy consumption for the return to productivity, quality and societal satisfaction. There are a range of greenhouse system technologies which can be adopted by growers to improve climate control and energy use. However, there are numerous obstacles and constraints to overcome. The existing technology and know-how developed in north European countries are generally not directly transferable to Mediterranean climate countries; high-level technology is beyond the means of many growers due to the high cost compared with the modest investment capacity; and know-how from north European growers is often inappropriate for the problems encountered in South Africa. Where these technologies may be adopted, it is necessary to train

and educate local growers. To this end, specific research and development tasks have been initiated by Universities with a Horticulture Department, Agricultural Research Institute and representative companies for European and other greenhouse companies. The issues addressed above concern the means and best practices by which

local growers can alleviate the climategenerated stress conditions that inhibit the growth and the development of crops during a long, warm season in a sustainable and energy-friendly way. By; Sjaak Bakker of Wageningen UR Greenhouse Horticulture et al.

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Pioneering the Future of Calcium Nitrate Nutrigation™ Haifa Chemicals is

All greenhouse growers will know that calcium (Ca2+) is an element that is required in large volumes by most plants. These include tomato, pepper, lettuce and cut flowers etc. However, calcium can be a very delicate nutrient to manage, not only in the nutrient solution, but also in the plant itself. Calcium is specifically known to cause chemical interactions with other nutrients when present in high concentrations, e.g. phosphates and/ or sulphates, within the same nutrient solution stock tank.

F

urthermore, certain growing systems and environments tends to create abiotic conditions that predispose a potential calcium deficiency within the plant or fruit. Selecting the correct fertilizer product for your unique farming system will ensure that your plants have the best possible fertilizer which promote nutrient uptake and results in optimal yield and quality. All greenhouse growers will know that calcium (Ca2+) is an element that is required in large volumes by most plants. These include tomato, pepper, lettuce and cut flowers etc. However, calcium can be a very delicate nutrient to manage, not only in the nutrient solution, but also in the plant itself. Calcium is specifically known to cause chemical interactions with other nutrients when present in high concentrations, e.g. phosphates and/ or sulphates, within the same nutrient solution stock tank. Furthermore, certain growing systems and environments tends to create abiotic conditions that predispose a potential calcium deficiency within the plant or fruit. Selecting the correct fertilizer product for your unique farming system will ensure that your plants have the best possible fertilizer which promote nutrient uptake and results in optimal yield and quality.

Haifa Cal™ Prime is the new improved and concentrated calcium nitrate fertilizer from Haifa South Africa. Haifa Cal™ Prime is 100% water soluble and is setting new standards with its near zero ammonium (N-NH4+) level. Standard calcium nitrate typically contains between from 1.1 – 1.5% ammonium nitrogen. Haifa Cal™ Prime contains 0.3% N-NH4. This unique property becomes very important when growing soilless crops, especially in NFT or soilless systems which have low buffering properties. Research by Kafkafi (1990) has clearly shown that elevated N-NH4+ levels and subsequent plant uptake becomes dangerous and detrimental within the plant at high temperatures and radiation levels. These challenging growing conditions, coupled with a dry/ low humidity climate, are typical to most of South Africa’s production areas.

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With elevated plant transpiration and subsequent water uptake, it is even more important to ensure a nutrient solution with near zero levels of N-NH4+ to reduce the potential toxic effect thereof within the plant. Haifa Cal™ Prime is highly concentrated and offers a 10% increase in nitrate (N-NO3-) contents and 24% increase in calcium compared to other calcium nitrate products. The higher level of nitrate nitrogen (N-NO3-) further promotes the uptake of other important cations, including Ca2+, Mg2+ and K+. The superior solubility compared to other calcium nitrate products, makes Haifa Cal™ Prime extra convenient to apply by Nutrigation™ or foliar spray. Further improvements with regards to hygroscopicity also ensures that Haifa Cal™ Prime remains dryer for longer when exposed to air. These characteristics make Haifa Cal™ Prime the ideal option when needing to supply you crop with the best source of watersoluble calcium nitrate on the market. Contact your closest Haifa distributor for details about this unique product offering.


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NEW

Haifa Cal™ Prime Concentrated Calcium Nitrate + More calcium + More nitrogen + Near zero ammonium Haifa's new prime grade of calcium nitrate offers multiple benefits for growers who seek the most precise results in challenging growth conditions. With high concertation and near zero ammonium level this new product sets new standards of calcium nitrate.

Ideal for soilless grown crops and hydroponics

Recommended for zones of high sun irradiation

Extra convenience in handling

Haifa South Africa

P.O.Box 1409, Brackenfell, 7561, South Africa Gerrit Burger | 082 8008766 | gerrit.burger@haifa-group.com Michael Koch | 083 2314516 | michael.koch@haifa-group.com www.haifa-group.com

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A Horticultural Cluster –

Solution for Sectoral Growth and Food Security Functioning on own merits and philosophies have never brought around powerful outcomes – not in politics, not in economies and neither in horticulture. The answer lies in grouping together experience, capabilities and resources in what one would call ‘clusters’. In the Netherlands a successful program was established and mirrored in Ethiopia to prove it is not only possible in a particular country.

T

he competitive strength of nations is determined by four interrelated determinants that shape the national environment. Factors of production can be categorized into several groups: Human resources: the quantity, skills and cost of personnel for a certain sector. Physical resources: the abundance, quality, accessibility and cost of the nation’s physical resources, such as climate, land, water and power. Knowledge resources: the nation’s stock of scientific, technical and market knowledge on goods and services. Infrastructure: the type, quality and user cost of infrastructure that affects competition. This includes the transportation system, the communication system, etc. as well as less obvious

infrastructure that affects the quality of Good cooperation between producers life and the attractiveness of a nation as a can, however, also form a competitive place to live and work. advantage if producers help each other to attain a higher qualitative or quantitative The structure of a company is level of production. determined by the style of management in a Clusters are geographic The structure company, or in a country concentrations of of a company is as a whole. Possible interconnected companies determined by the differences in management and institutions in a styles can, for example, style of management particular field. As such, result in more hierarchical in a company, or in a they must combine all the company structures best of the determinants country as a whole. or in more flattened mentioned above. In company structures. Rivalry between general, clusters encompass arrays of companies in a country spurs innovation. linked industries and other entities that Domestic rivalry is more intense and are important to competition. This motivating than international competition, implies that, besides regular competitors, because within a domestic rivalry all clusters can also include manufacturers of companies are on a level playing field. complementary products and companies

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Two of the challenges of cluster development in Africa are the lack of in industries that are related by skills, critical mass of skills and talent, and the technologies or common inputs. weak links between b Upstream, suppliers of specialized inputs and providers of specialized infrastructure Companies are becoming can be included. Downstream, the cluster more knowledge and technology intensive can extend to channels of customers. and knowledge Finally, governmental and other based. Another institutions (universities, think tanks, challenge is trade associations) can also be included. the weak Developing countries are facing tough government new challenges. Their competitive and environment is characterized by institutional globalization, liberalization and support and extensive organizational, institutional also resource and technological change. In order depletion to survive in these circumstances, and failure to companies in developing countries must meet international be able to face increasing competition. standards. Since many enterprises in developing The following are possible policy countries are small or medium sized implications to tackle these challenges: enterprises (SMEs), an industrial strategy much referred to is clustering. This Encourage further knowledge acquisition, holds especially adaptation and Two of the challenges of for the agro dissemination, cluster development in Africa strengthen sectors, because in developing are the lack of critical mass of educational countries especially skills and talent, and the weak institutions and these sectors are links between businesses and technology institutes characterized by the and their links knowledge institutions. presence of SMEs. with the business

sector, establish and enforce a business conducive institutional plan, including clear regulations, standards and quality assurance mechanisms, strengthen and upgrade skill training, provide infrastructure and, in the long run, promote greater consumer purchasing power. Thus, governments can play a very important role in cluster creation. Some of the most important challenges that a horticultural cluster must overcome are: Meeting the high quality standards of foreign consumers, production, post-harvest and logistical arrangements and facilities in the flori- and horticultural business have ample scope to improve performance and product quality. This is also very much needed and should be given high priority in order to meet consumer demand, to seize market opportunities and to improve the competitive position. From a discussion around the effect of clusters in an African country, by the economist Michael Porter(EU).

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Purging is the processes whereby fish are held in clean water and not feed for a period of time. Purging is a useful protocol employed by fish farmers to reduce the stress on fish during handling and transport, and to minimise unpleasant flavours in the fish’s flesh.

period of time prior to size sorting,

Aquaculture techniques:

Purging Fish

P

urging is the processes whereby fish are held in clean water and not feed for a period of time. Purging serves two primary purposes: • Reducing the amount of faecal material in the gut which reduces the level of stress encountered by the fish during handling or live transport, and • Reducing or removing off flavour in the flesh prior to slaughter.

harvesting or transporting them, we reduce both the oxygen shortage and metabolite toxicity stressors, allowing the fish to travel and arrive in a far healthier state. The primary factors determining the duration of purging for handling or

Purging for handling or transport Digestion utilises oxygen. As such, if fish are handled or transported after normal feeding they experience increased stress during handling as well as transport, as the body struggles to obtain adequate oxygen from the water for digestion and dealing with heightened stressors. Furthermore, normal feeding is followed by normal rates of waste excretion from the body, which can quickly pollute the transport water, adding yet additional stress. By withholding feed for a limited

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transport are the size of the fish and the duration of the handling or transport event; small fish and shorter time periods require less purging. Small fish may require 6 hours of purging prior to handling or overnight purging prior to a 12 hour long trip. Larger fish going on a 24 hour trip may require 3 days of purging prior to being packaged and shipped.

Purging for slaughter The feed that fish consume and quality of water in which they live, can impact its flavour. As such, normally fish is purged prior to slaughter in order to evacuate their gut as this lessens or removes the off-flavour associated with feed. In addition, hold the fish in clean water for the duration of purging to rinse out water borne flavour affecters. By doing these two things simultaneously for 24 to 72 hours you are able to get rid of all unpleasant tastes in the flesh. Clearly you need to know why you are purging your fish in order to apply the more appropriate method of purging them. Systems differences Most fish species cannot be purged in earths pond as they will find food to eat in the pond even though all artificial feed is withheld. The exception would be predatory species such as trout or eels that will not be able to find appreciable quantities of feed and can be purged reasonably effectively in ponds. Cages in a green water environment are similarly ineffective for purging fish that feed low on the food web as they can find some feed in the cage and importantly the green water still results in off-flavours persisting.

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Clean water cages are perfect for purging, as are tanks where clean water can be run through the tank and feed withheld.

Weight loss during purging Fish will lose some body mass and an element of stress will ultimately result from purging but this is unavoidable. The point though is not to purge the fish, especially small fish, for longer than is necessary. Purging is a useful protocol employed by fish farmers to reduce the stress on fish during handling and transport, and to minimise unpleasant flavours in the fish’s flesh. Be sure to purge the fish correctly though to maximise the benefits without incurring undue stress or harm. By: Leslie Ter Morshuizen, AquaAfrica

The Benefits of Aquaponics The benefits of using an aquaponics system to grow food are becoming more important due to population growth making fresh water more scarce, and pollution more prevalent within the world. Here are some of the reasons why aquaponics is such a hot topic. Fast Plant Growth Providing nutrients and an oxygen rich environment for the roots of aquaponic plants makes them grow 3 times as fast compared to soil. The flavour of the plants is better too, as they have more time to focus on healthy growth rather than placing energy into extending their root system to look for water. Health The fish you grow are free from pollution unlike many sourced from the sea. This goes for the vegetable and herb produce too; you have control of what goes into the system. All the produce grown within an aquaponics system is important for a healthy lifestyle. Reduced Chemical Use When an aquaponics system is setup within a greenhouse or insect mesh there are very few bugs to manage. Pesticides are extremely dangerous to fish, so they are not recommended for aquaponics. As chemicals can be introduced, you’re guaranteed clean and non-toxic produce, completely organic (depending on where you live!). Food Localisation An important benefit of an aquaponic system is that it produces fish and plants for the family or grower all year round without leaving their backyard. A family will save time and fuel without having to shop for the same items, and use more healthy herbs and veggies in their cooking.

18 Undercover farming I July/August 2021 I Volume 18 No 4

Food Security Many consider that one of the main benefits of aquaponics is having a replenishing food source at home. Owners can rest assured they will never go hungry, and they have fresh produce to barter with too. Reduced Water Use Compared to soil gardening, aquaponics uses 90% less water. An aquaponics system continuously recycles water through the plants and fish tank, so the only water lost is through evaporation from the fish tank (when uncovered), and from the plants’ transpiration. Smarter Farming Aquaponics reduces erosion by eliminating the need to turn or plough the soil. The backbreaking work of turning soil and pulling weeds is gone, reducing the cost compared to a conventional horticultural farm. Imagine gardening with your plants at waist height – now that is smart! From: Aqua Gardening


greenhouses I shade net I hydroponics I aquaponics

Product Control for Agriculture (PROKON) has noted and welcome the ruling by the Supreme Court of Appeal on 13 July 2021, which found that the appointment of Assignees in terms of the provisions of the Agricultural Products Standards Act, No. 119 of 1990 (“APA”) is constitutional, valid and binding.

Prokon welcomes Supreme Court Ruling

P

ROKON and all Assignees countrywide are consequently entitled to charge the fees as determined in terms of the APA. The organizations’ fees as gazetted on 6 January 2017 were reviewed and set aside by the court on procedural grounds as stipulated in the Judgment. Consequently, all fees charged up to date of Judgement, being 14 July 2021 remain valid and binding. In respect of all future fees to be charged, PROKON in conjunction with its advisers and various stakeholders in the industry are currently working on implementing a new fee regime consistent with the provisions of the APA. It will also undertake a full consultative process, as delineated by the Court, to strictly meet the requirements of procedural fairness, as well as

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consultative process in its obligations in terms of the APA, the Promotion of Administrative Justice Act 3 of 2000, as well as the Constitution of the Republic of South Africa. According to PROKON, the organization

Electronic subscription for 6 bi-monthly issues is R 350.00 (ZAR) annually

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Undercover

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J U L Y/A U G U S T 2021

I VoLUme 18 No 4 I  I R45.00 per issue

For more information contact Suzannne Oosthuizen (+27) (0) 82 832 1604 or e-mail suzanne@axxess.co.za

HeALTHY SeedLiNGS

cLimATe coNTRoL

HoRTicULTURAL cLUSTeR

AqUAcULTURe: PURGiNG FiSH

moorland Seedlings Nursery Page 4

Greenhouse climate control and Sustainable energy Use Page 10

Solution for Sectoral Growth and Food Security Page 14

Aquaculture Techniques: Purging Fish Page 16

is content that its mandate has been affirmed by the Supreme Court of Appeal and is looking forward to the meaningful engagement regarding the fee structure to be implemented shortly. Source: Prokon

ADDRESS: CODE: CONTACT NUMBER: Account Name: Nufarmer Pty Ltd t/a Undercover Farming Bank: First National Bank, Kolonnade Branch Code: 25 10 37 Account No: 62007699806

Undercover farming I July/August 2021 I Volume 18 No 4 19


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Undercover Farming Magazine July/August 2021  

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