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European Fertilizer Manufacturers Association

S U S TA I N A B L E

SOIL MANAGEMENT

A N A C H I E VA B L E G O A L


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European Fertilizer Manufacturers Association

S U S TA I N A B L E

SOIL MANAGEMENT

A N A C H I E VA B L E G O A L


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S U S TA I N A B L E S O I L M A N A G E M E N T TABLE OF CONTENTS

Sustainability ...................................................................................................................................................................................... 3

Towards sustainable agriculture in Europe ....................................................................................................................... 4

The importance of the soil ........................................................................................................................................................ 7

Soils under stress .............................................................................................................................................................................. 9

Sustainable soil management .................................................................................................................................................17

Conclusion ......................................................................................................................................................................................... 25

Sources and recommended further references ........................................................................................................... 26

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A N A C H I E VA B L E G O A L

SUSTAINABILITY It was as chair of the World Commission on Environment and Development that Dr Gro Harlem Brundtland, the former Prime Minister of Norway, in her 1987 report to the United Nations, introduced us to the word 'sustainability'. The report, Our Common Future, came to be known as the Brundtland report, and the term sustainability became an international aspiration, giving the world a focus and a common goal to work towards. Since that time, n a t i o n a l , E u ro p e a n a n d i n t e r n a t i o n a l b o d i e s h a v e b e e n re m i n d i n g u s o f o u r j o i n t responsibility to live our lives in a way that does not jeopardise the chances of future generations to live their lives, and they continue to propose guidelines or introduce regulations to that end.

The Brundtland report inspired the United Nations Conference on Environment and Development (UNCED) ‘Earth Summit’ in Rio in 1992, which produced Agenda 21, a declaration concerning agriculture and rural development. In Agenda 21, the Earth’s capacity to satisfy the demands of a growing population was examined. Major adjustments in agricultural, environmental and macroeconomic policy were recommended, with a view to creating the conditions for sustainable agriculture and rural development (SARD). It was suggested that production should be increased mainly on land already in use and that further encroachment on land that is only marginally suitable for cultivation should be avoided.

Agriculture as an economic sector was a major focus for the UN Commission on Sustainable Development in 2000, when the major objectives of increasing food production and enhancing food security in an environmentally sound way were reaffirmed. It was noted that although food security for all countries is a policy priority, it remains an unfulfilled goal.

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TOWARDS SUSTAINABLE AGRICULTURE IN EUROPE Policies In its 1999 document Towards Sustainable Agriculture, the European Commission noted the significant link, throughout the EU, between agriculture and the conservation of the environment. It also pointed out that while the intensification of agriculture had, in some areas, accelerated erosion, in other areas, the abandonment of farmland had reduced the diversity and aesthetic value of the countryside. The document also explained the concept of ‘cross-compliance’ contained in the reform of the Common Agricultural Policy that was adopted in 1999, whereby direct payments are to be linked to environmental programmes and farmers reimbursed for environmental services that exceed the requirements of Good Agricultural Practice.

Responding to a request from the European Council, in January 2000, the Commission published a report entitled Communication

on

Indicators

for

the

Integration

of

Environmental Concerns into the Common Agriculture Policy. In this document, in a section on land use and soil, it is stated that erosion should be countered, adequate farming systems promoted, soil surface nitrogen balances improved and the destruction of landcover reduced.

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Practical ways forward Its soils and climate make Europe a particularly fertile and productive food-growing region, and the population of Europe has an important role to play in safeguarding the fertility and food-growing potential of its lands. Often called the caretakers of the land, farmers are in the spotlight when such responsibilities are discussed. While farmers certainly play a major part in caring for the land, all of us – whether we are farmers, consumers, agronomists, policy makers or supply industries – have a shared interest in, and commitment to, safeguarding the wellbeing of the land.

As members of an important agricultural supply industry, the European manufacturers of mineral fertilizers, represented by EFMA, are major stakeholders in agriculture. The farmer’s main asset, the soil, is the basis of our existence, and a policy of responsible care that maintains a healthy farming sector with healthy soil is the key to our survival. By undertaking to supply agriculture with high-quality plant nutrients, by maintaining and further developing clean, energy-efficient production processes, and by promoting the sustainable use of its products, the members of EFMA make an active contribution to sustainable agriculture.

One of EFMA’s main activities is the investigation of the interrelation of agriculture and the environment, in order to establish and promote Best Management Practices in agriculture.

EFMA firmly supports the concept of Integrated Plant Nutrition (IPN), which emphasises the importance of fertilizer planning at the farm level and promotes the use of all the nutrients available on a farm to the best advantage of the farm’s cropping system. EFMA also supports Integrated Crop Management (ICM), which combines, on a whole-farm basis, the aims of producing food in an efficient and economical way and conserving finite resources and protecting the environment at the same time.

To

this

end,

EFMA

p ro m o t e s

a

Code

of

Good

Agricultural Practice: Nitrogen, which is based on principles such as the Nitrogen Budget, the Fertilizer Plan and Fertilizer Practice for Water Protection, and a Code of Best Agricultural Practice: Urea, which provides guidelines for the effective use of urea on agricultural crops under European conditions.

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As an experienced industry that has been gathering knowledge about the interaction of its products with specific crops, soils and climates for many years, the European fertilizer industry has been able to develop comprehensive decision support systems for farmers and agricultural advisers. EFMA is able to draw on the industry’s knowledge of plant nutrition and soil fertility to identify and promote solutions for good management practices for the future.

â–˛ Fertile soil is precious and the farmer's main asset.

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AN ACHIEVABLE GOAL

THE IMPORTANCE OF THE SOIL Soils are the point of interaction between the two basic processes in ecosystems: production, the generation of biomass by green plants, and decomposition, the subsequent breakdown of this biomass. In the lives of plants, animals, microorganisms and people – but also in energy, water and material budgets – the soil fulfils several important functions, which are described below.

Habitat function Soils provide a habitat and the means of survival for a wide variety of plants, fungi, animals and microorganisms. The metabolism of these organisms is the basis for the regulation function and the production function of soils (see below). Soil organisms are responsible for transforming organic substances in soils, added to which they play a major role in stabilising ecosystems and make an important contribution to biodiversity. Soils provide plants with their rooting medium and serve as a supplier of water, oxygen and nutrients. They are therefore the basis for the primary production of terrestrial systems and, at the same time, for all higher organisms in the food web, including human beings. In addition, soil is a habitat for people, for whom land represents ‘territory’ that they inhabit and utilise.

Regulation function Soils regulate the exchange of substances between the hydrosphere and the atmosphere. They act as a buffer for acids, and they filter substances from rainwater, infiltration water and groundwater. The soil provides storage capacity for water, nutrients and harmful substances, and at the same time it recycles nutrients, detoxifies harmful substances and destroys pathogens.

Utilisation function T he soil is also said to have a utilisation function, which can be divided into two main subfunctions :

Production function As consumers of vegetable and animal foods, people are ‘consumers’ of soils, and, with the steady increase in population growth, the utilisation of soils for agricultural and forestry production has become increasingly important for human society. In addition to agriculture, a further production function is the exploitation of natural resources such as coal, oil, gas, peat, sand, gravel, rocks and minerals. The extraction of these raw materials usually involves the destruction of soils.

Carrier function The term 'carrier function' is used to refer to the use of the land for settlements, transport, supply and disposal, for industrial and commercial production and for the disposal of waste.

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Cultural function The preservational properties of soils mean that they are an ‘archive’ for natural and cultural history, telling us much about our past. Many soils have been cultivated by farmers for centuries, and there is an increasingly strong movement in favour of preserving this cultural heritage in Europe.

Global aspects of soil functions The functions of soils that are considered to be particularly important from the global perspective are:

Habitat function - Soils contribute to biodiversity - Soils represent a genetic pool

Regulation function - Soils influence the exchange of radiation - Soils regulate the hydrological cycle of the continents - Soils are stores and transformers of nutrients - Soils are sources and sinks for carbon dioxide and methane - Soils are sources of nitrous oxide - Soils are buffers, filters, transformers and stores for pollutants - Soils are sources for the contamination of neighbouring environmental compartments

Utilisation function - Soils form the basis for food production

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SOILS UNDER STRESS Like air and water, the soil is a precious resource. However, it is not an unchanging resource. On the contrary, the quality and quantity of soil in any one location can change markedly in a relatively short time-span. Such changes may result from human activities, from natural processes or from a combination of the two.

The European Commission recently published a report on soil degradation in the EU (Agriculture, Environment, Rural Development: Facts and Figures - A Challenge for Agriculture, EUROSTAT, 1999). This report suggests that among the various forms of soil degradation, soil erosion in particular is a serious problem in the EU, with more than half the land in Europe having suffered various degrees of erosion by water and about a fifth having been eroded by wind. The problem is at its most acute in some parts of the Mediterranean region, where erosion has resulted in the exposure of extensive areas of bare rock. Although the historical effects of erosion can be beneficial (many of today’s best agricultural soils are deposits of formerly eroded material) the displacement of soil by water and wind is, at present, robbing the farmer of his main asset and reducing the farming opportunities of future generations. Erosion can also trigger environmental problems.

Soil in movement Many people associate erosion with arid, windswept regions of the world or with areas of former rain forest, where heavy rains on unprotected, hilly land can cause catastrophic instances of erosion. However, European soils are also being eroded. Managed in an inappropriate way or abandoned, soils in some areas may experience a reduction in quality and quantity that renders them infertile – in some cases, irreversibly so.

What exactly is erosion and how does it occur? Rainfall is the most common cause of erosion. With an impact of up to 30 mph, rain can easily displace soil. In general, the occurrence of water erosion depends on factors such as climate, topography and soil characteristics. Runoff occurs when rain falls at a rate that exceeds the soil’s capacity to absorb water and the gradient of the land allows water and soil to flow downhill. In Northwest Europe, where rain falls on gentle slopes in the main and is fairly evenly distributed throughout the year, rates of erosion average 0.24 t/ha a year. In the mountainous regions of France, losses range from 1.8 to 2.5 t/ha a year, while in small valleys in the Alps and the Apennines, losses can reach 25 t/ha a year.

Sometimes, soil is removed from sloping land in thin layers, a phenomenon known as sheet erosion. The most common form of erosion by water, however, is rill erosion. This occurs when soil is removed by water running in small streams through land with poor surface drainage. It is common for rills to form between vertical crop rows, though the farmer can

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often be unaware of the process since its effects are easily covered up by tillage. A more advanced form of rill erosion is gully erosion. Gullies can cause substantial damage to fields and cannot be corrected by tillage.

Wind erosion can occur even on flat land if the land has no vegetative cover and is dry. When particles of fine silt or clay and organic matter are transported by the wind, they carry the nutrients they have absorbed with them. This selective displacement of soil material leaves behind impoverished, coarse-textured soil particles. ▲ Gully erosion Environmental damage caused by wind erosion includes the pollution of the air by fine dust particles and the covering of fertile land with infertile deposits. In extreme cases, productive land can be buried under dunes. Water erosion, on the other hand, can – in addition to reducing soil quality and productivity – carry phosphorus into bodies of fresh water, which can increase the risk of eutrophication, or the over-enrichment of water with nutrients. In areas with high accumulations of nutrients in the soil because of the excessive application of animal manure or the inappropriate use of mineral fertilizers, nutrients are more prone to leach into groundwater or rivers or be carried overland with run-off to nearby surface waters. ▲ Wind erosion

N u t r i e n t - r i c h w a t e r s c a n re s u l t i n a h i g h e r- t h a n - a v e r a g e growth of algae, the decomposition of which can lead to oxygen starvation in the water, killing fish and other aquatic life forms.

Soil under pressure Another form of soil degradation is compaction, which occurs when soil particles are compressed by heavy machinery or the trampling of animals. Compaction reduces the soil's porosity, and when this happens, plant roots are less able to penetrate the soil. In addition, water drainage and air diffusion are restricted. Wet clays are more susceptible to compaction than sandy soils. The ▲ Bad timing and inappropriate equipment damage the soil's structure.

negative effects of soil compaction can be remedied to varying degrees depending on the structural damage, by using special tillage techniques to break up the soil.

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AN ACHIEVABLE GOAL

Soil without life In some dry regions of the Mediterranean area, the removal of vegetation started a process that has ended in desertification. The vulnerable soil surfaces of such regions have little organic matter and a reduced capacity to store water, thus exposing them to further erosion processes. The affected regions seldom recover any vegetation and thereby become part of the 40% of the Earth’s surface composed of drylands susceptible to desertification (UNEP Global 2000). Today, more than 1,000 million people are affected by soil degradation in such areas of the

▲ Desertification is widespread in part of southern Europe.

world.

Soil out of balance Other forms of soil degradation are the result of chemical changes in the soil’s composition. Acidification, for example, occurs naturally as a result of acidifying deposits from the atmosphere and microbial activity in the soil. Intensive industrialisation and the burning of fossil fuels produce acidifying emissions, thus exacerbating the problem. Acidification reduces the availability of nutrients such as phosphorus to plants, it increases aluminium toxicity, and it adversely affects the physical and microbial condition of the soil. Regular liming is required to counter these adverse effects.

Salinisation, the accumulation of salts on or near the surface of the soil, is a process that results in completely unproductive soils and which currently affects nearly 4 million hectares of land in Europe, mainly in the Mediterranean region and in East European countries. It is particularly common on irrigated soils in hot regions, where water tends to evaporate before it has time to seep into the soil. A common solution, but one that is expensive and cannot be considered sustainable, is to over-irrigate, applying more water than the crop can use.

Serious changes in the soil’s chemical composition can take place when nutrients are removed from the soil by repeated harvests and are not replaced by organic or mineral fertilizers. When the soil’s nutrient status and fertility are reduced in this way, soil mining is taking place. The same phenomenon can be observed with soil organic matter: inappropriate soil management and crop sequences may exhaust the organic matter content of the soil, having negative effects on soil structure, water and nutrient storage capacity and water drainage. Finally, excessive accumulations of potentially hazardous substances can lead to contamination of the soil.

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Soil mining and acidification can both have serious environmental consequences in that they result in the inexorable deterioration of soil fertility and, subsequently, in a decline in soilfixing root development and plant growth. This greatly enhances the risk of erosion.

Global issue: soil management and climate change Emissions of carbon dioxide and nitrous oxide, which increase the concentration of greenhouse gases in the atmosphere, can be caused by soil degradation, deforestation, soil drainage or ploughing. Soil compaction also increases emissions of nitrous oxide by creating areas that are deficient in oxygen. Enhancing the efficiency of nutrients in soil and fertilizers, and preserving or building up the organic matter content of the soil acts as a counter measure. The conservation of organic matter in the soil creates a sink for carbon dioxide, which is a welcome soil function in the context of climate change.

On the other hand, excessive amounts of organic matter in the soil also increase the risk of nitrous oxide forming under oxygen deficiency conditions. Conversely, under oxygen-rich conditions, microbes become particularly active in breaking down organic matter, which increases the risk of carbon dioxide being released. The potential emission of these greenhouse gases as an effect of soil degradation and soil management has to be taken into account by policy makers and farmers, particularly when sudden changes in soil management (e.g. the introduction of set-aside and abandonment of fertile soils, the ploughing of old grassland areas, or the cultivation of moors) are considered.

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When agricultural soils are badly managed Since over three-quarters of the territory of the European Union is agricultural and wooded land (44% agricultural land, 33% wooded land; EC, 1999), agriculture has a significant impact on European soil. Certain agricultural practices can effectively increase the risk of soil degradation.

Examples of bad management practices include:

• depleting vegetative cover • damaging the soil structure • farming land that is unsuitable for the purpose • excessive levels of manure • depleting soil resources (i.e. organic matter and nutrients) • mismanaging irrigation • damaging watercourses

Depleting vegetative cover creates opportunities for surface erosion by strong winds or heavy rains. The effects are particularly noticeable when bare, dry soil that is weak in structure is exposed by the burning of straw after the crop has been harvested, or when pasture is overgrazed by livestock. The use of heavy machinery on wet, loamy soils, and overgrazing or trampling by livestock can damage the soil’s structure by compaction.

Activities such as

continued cropping with excessive soil tillage cause rapid decomposition of the soil’s organic substance. Lime needs to be added to soil not only to neutralise acidification but also to stabilise the soil particle

▲ Erosion in neglected olive plantation.

cohesion and structure. It is important to note that acidification also occurs on abandoned land and in forest regions. It is, moreover, interesting to note that regional marginalisation and the abandonment of land, as with set-aside, though often thought to be environmentally beneficial practices, can in fact accelerate soil degradation in previously fertile land. In areas with a dry climate, this can also lead to desertification.

Hilly, forested areas have been, and continue to be, converted into agricultural land, particularly in tropical regions. Such areas are often unsuitable for farming. Heavy rainfall and a warm climate quickly degrade the upper layers of the soil, mainly through erosion and

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microbial breakdown of soil organic substance. But also under less extreme climatic conditions, as in western Europe, growing maize in hilly areas (often former grassland), for example, has caused huge soil losses by erosion. In Mediterranean countries, old olive plantations in hilly areas have been cleared, leaving the soil exposed, and where they have been replaced, it has been by less suitable crops. This is leading to extensive erosion and soil losses in southern Europe. Furthermore, the over-intensive use of pasture by high densities of livestock causes erosion in many hilly regions of Europe.

In areas with a high density of livestock (the Netherlands, parts of northern Germany, Belgium, northern France), the amount of manure produced is far too high for it all to be used on the available land. However, since transportation of these wastes to other areas with lower livestock populations is costly, local soils have been receiving excessive levels of manure for many years. This practice has resulted in high regional accumulations of organic matter and nutrients beyond the level that can be retained by the soil. The same effect can be caused by the over-application of manufactured fertilizers. Microbiological functions can suffer severely and might take decades to recover.

Economic or regulative pressures can force farmers to mine the soil, meaning that they deplete its reserves by failing to replenish resources in line with crop yield and crop quality parameters. Consequently, in the long run, losses in yield level and quality are predictable, since the soil is being progressively worn out. Once a critically low nutrient level in the soil has been reached, only high applications of fertilizer will gradually build up soil fertility to previous satisfactory levels. Long-term experiments show that this soil recovery process can take decades. Long-term experiments have also demonstrated that without appropriate applications of fertilizer, a decline in the soil nutrient status, in soil fertility (yield), soil coverage can occur. There is a link between soil fertility and erosion, which would suggest that allowing nutrient reserves to become reduced could have a seriously detrimental effect on agricultural land.

Mismanaging the application of water in agriculture can cause soil degradation in different ways. Too much water can cause losses of soil substance in the form of runoff (i.e. water erosion). In arid and semi-arid regions, however, irrigation practices often fail to keep pace with natural leaching, thereby causing salinisation. Finally, allowing grazing cattle to have access to natural watercourses can cause banks to break down, thereby damaging water courses and allowing erosion to set in.

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Lack of awareness regarding soil degradation in Europe It is more often a lack of information about soil erosion than conscious malpractice that leads to neglect of the land. Economic, and sometimes regulatory, pressures can also have an effect. Regulatory mechanisms such as the removal of olive trees as a precondition for set-aside, for example, have been known to cause problems of erosion, especially when the planting of substitute crops is not foreseen. There are numerous community-wide initiatives and programmes at the regional and national level which have a bearing on the protection of the soil. The first step in preventing or controlling

â–˛ Manure application needs to be tailored to the specific site and crop.

further damage from different forms of soil degradation is to monitor the processes that occur and to analyse and assess potential risks in the various regions of Europe.

Assessing the risk Generally, the risk of soil degradation is present throughout the E u ro p e a n U n i o n . S y m p t o m s c a n b e f o u n d i n v i r t u a l l y a l l agricultural regions and production systems. Some regions are particularly vulnerable to erosion for climatic and topographic reasons, while other areas have received high applications of livestock manure, resulting in high organic matter and nutrient accumulations that can lead to polluting emissions and disturbed

â–˛ Over-irrigation can cause erosion.

microbiological processes in the soil. The potential risk of erosion arising from the removal or lack of protective vegetative cover is significant, even on gently sloping land, and considerably exceeds the tolerance level. In Belgium, for example, 10% of agricultural land is considered to be susceptible to water erosion. In extreme cases, rates of soil loss as high as 82 t/ha a year have been reported on bare fallow land with 5-7% slopes. Water erosion is also the dominant form of soil erosion in France, where it affects about 5 million hectares of agricultural land (about 17% of the total). In fact, soil erosion is reported to affect most of the main cereal growing areas in France.

In the Mediterranean region, climate, strong relief (characterised by steep slopes and exposure to the elements) and a long history of human interaction with the natural ecosystems have resulted in high rates of soil erosion more frequently than in other regions of the continent.

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According to the results of the CORINE assessment (1992), about 66% of the rural area displays a moderate to high potential risk of soil erosion by water. The distribution of the risk in the region, and within the individual countries, is complex. A large proportion of land in Portugal, Greece and Spain (68%, 43% and 41% respectively) is at high risk f ro m

soil

e ro s i o n ,

w h e re a s

the

c o r re s p o n d i n g

proportions in Italy and in Mediterranean France are less (27% and 9% respectively). â–˛ Rain simulation and erosion measurement. (University of Bonn)

High-risk areas, which due to their gradient and climate could experience soil erosion, are to be found

in the Pyrenees, the Alps, the Apennines and the Pindos mountain range. Also at risk are areas of rugged terrain throughout Portugal, in Southeast Spain, in Corsica, in Sardinia, Calabria and Sicily in Italy, and in Crete and the Aegean Islands in Greece. The area currently at risk from erosion, given the present vegetative cover, is considerably smaller than the area of potential risk and is estimated to cover 30% of Portugal, 29% of Spain, 1% of Mediterranean France, 10% of Italy and 19% of Greece.

Information on the extent and severity of desertification in Europe is limited, though the United Nations Convention to

â–˛ Furrow irrigation in Spain.

Combat Desertification (UNCCD), in its Regional Implementation annex (Annex IV), addresses the extensive desertification phenomena of the northern Mediterranean countries.

Research and data collection on the status of European soils has been undertaken within the EU by the European Soil Bureau (ESB) of the Joint Research Centre in Ispra, Italy and by the European Environment Agency. Work has also been carried out by international organisations such as the European Society for Soil Conservation (ESSC) and the European Conservation Agricultural

Federation

(ECAF),

Investigaciones Desertification).

16

and

by

re g i o n a l

associations

like

CIDE

( C e n t ro


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SUSTAINABLE SOIL MANAGEMENT Understanding the process Safeguarding the quality and quantity of European soils requires active soil management. For this to be successful, those involved in the management of the soil must have a thorough understanding of the geology, topography and climate of the area they are caring for. Although it is possible to make regional generalisations about soil to some extent, accurate assessments can only be made if soil conditions are ascertained at the farm level, where there can even be differences between one field and another. Some of the methods currently used to sustain the quantity and quality of agricultural soils are techniques that have been practised for centuries, while others are newer techniques, developed as a result of more recent advances in science and technology. The use of mineral fertilizers combined with soil analysis techniques to supplement the organic nutrients available on farms is an example of scientific advances that have led to greater precision in farming and protection of the soil.

Active soil management, based on a thorough knowledge of the area concerned and motivated by the desire to sustain the quantity and quality of the soil, leads us to seek the most appropriate use for a given area of land. Where the soil is stable, fertile, cultivated and managed in a sustainable way – by ensuring the replenishment of organic matter and plant nutrients to compensate for the plant matter and nutrients that are removed with the harvested crop – we are likely to continue agricultural activity. Where, however, soils are less stable, less fertile or less well suited to certain forms of agricultural production, we need to manage the soil differently or identify a more appropriate use for the land. This may lead us to take one of the following decisions:

a) to leave the land, making an active decision not to interact with it b) to take protective measures designed to prevent potential imbalances or site-specific problems c) to take counter measures to reverse critical situations

Identifying solutions Having assessed the risks of soil degradation and identified the regions affected, the next step in implementing sustainable soil management is to identify site-specific solutions to the current problems. Agriculture has a key role to play in this process, much of which has to do with protecting fertile soils. Productive agricultural soils are a precious and limited resource, but increasing global food demand will ultimately force all regions of the world with high soil fertility and a favourable climate, such as Europe, to contribute to and take responsibility for meeting global food demands.

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Wheat yield in tonnes per hectare in key producing countries, 1999 (FAO, 2000) United Kingdom

8.0

India

2.6

France

7.2

Argentina

2.5

Egypt

6.3

Canada

2.6

Mexico

4.8

Pakistan

2.2

China

4.0

Australia

1.8

Poland

3.5

Russia

1.3

United States

2.9

Kazakhstan

1.3

Ukraine

2.3

The outstanding yield levels of European agriculture are based on intensive farming methods that make use of appropriate and highly efficient inputs. Only fertile, healthy soils can sustain such yield levels, and nutrients removed with the harvested crops have to be re p l e n i s h e d a c c o rd i n g l y. T h u s , i n i n t e n s i v e f a r m i n g , s u s t a i n a b l e l a n d u s e a n d t h e maintenance of soil fertility are major challenges for farmers. Land that is under intensive cultivation needs careful management, but also marginal and set-aside lands require good care in order to combat soil degradation and to maintain long-term farming options for future generations. Sustainable soil management measures designed to avoid degradation and to maintain soil fertility are based on Best Management Practice (BMP).

Best Management Practice involves: • protecting soil structure and organic content • managing nutrients • conserving the soil with plant cover • planting forests • maintaining the fertility of the soil • using advanced techniques such as fertigation • applying appropriate cultivation techniques

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Best Management Practice (BMP) - the concept Best Management Practice (BMP) describes the concept of combining soil management practices and other agricultural management practices to arrive at the most effective and economic way to avoid soil degradation. In the case of erosion control, these practices include reducing physical and chemical stress to soils (e.g. protecting the soil against raindrop impact), reducing runoff, restricting runoff velocities, and avoiding the use of heavy machinery at times when the soil is vulnerable.

Protecting soil structure and organic matter The structure of the soil is determined by the size of the soil particles, their distribution and the organic matter content in the different layers of the soil. The spatial distribution of the soil particles determines the volume of the soil’s pores and, therefore, its oxygen and water storage capacity and availability. Fertile soils have a rather light structure, ensuring good water drainage and storage and the availability of oxygen. They work like a sponge, storing and then slowly releasing water. The organic matter content can be regulated by applying livestock wastes or by incorporating straw. On grassland, organic matter is built up with the accumulation of root remains.

Managing nutrients The ability of soils to store and release nutrients depends on their structure, organic matter, mineral content and particle size fractions. Water content is particularly important for the mobility of nutrients, while the pool of organic matter that has been built up over generations can act as a source or a sink for nutrients, accumulating or releasing them into the soil solution or atmosphere. Soil analysis and soil tillage are some of the instruments that enable farmers to manage the nutrients that are found in the soil’s reserves. Manufactured fertilizers serve as a targeted supplement to the farm’s own resources, which often take the form of livestock manure.

▲ Soil sampling to assess the soil's nutrient reserves

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Successful nutrient management implies matching the nutrient supply in the soil to the nutrient re q u i re m e n t s

of

each

c ro p ,

supplying any shortfall in the form

of

o rg a n i c

fertilizers.

In

this

or

mineral

w a y,

the

nutrients that are taken up by c ro p s

and

re m o v e d

during

harvesting are replaced (Good Agricultural Practice: Nitrogen, EFMA, 1997; Code of Best Agricultural Practice: Urea, EFMA, 2000).

When

added

in

a

responsible manner, nutrients in Timing of fertilizer application and

â–˛

the form of manufactured or organic fertilizers increase the

exact calibration are essential in order to

quantity and quality of the crops and maintain or improve soil

achieve good yields and high quality.

fertility while avoiding oversupply and losses.

Conserving the soil with plant cover Plants protect soils from erosion, both above and below ground. Above ground, the stems and leaves act as protective barriers, preventing wind and water from eroding the soil, while below ground, plants reduce erosion by binding and anchoring soil particles with their roots. Crop residues also help to prevent erosion by absorbing the energy of raindrops, thereby reducing soil splash. In short, plants and close-growing crops minimise raindrop impact, hold the soil together and act as a filter, while crop residues, plants, rough soil surfaces, and gradual slopes help spread the flow of water over a wider area, thereby reducing the velocity of the runoff.

Typical cover crops include grass, legumes or small grains grown between regular production periods or between the rows of the main crop for the purpose of protecting and improving the soil. To control water erosion, winter cover crops are planted that hold the soil together u n t i l t h e s p r i n g , t h e re b y h e l p i n g t o k e e p nutrients in the soil and reduce run off. Cover c ro p s a l s o p ro t e c t t h e l a n d a g a i n s t w i n d erosion. It should be noted, however, that the â–˛ Grass covers the soil between maize rows.

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cultivation of cover crops is often restricted in areas with a limited water supply (e.g. southern Europe).

Planting forests In those Mediterranean areas where the risk of erosion is high, the planting of forests is an appropriate practice to aid soil conservation. Experiments indicate the advantages of fertilizer use in speeding up the growth of young trees in order to establish forests.

Maintaining the fertility of the soil Since industrialisation and the discoveries that led to a better understanding of plant nutrition and the means to produce mineral fertilizers, farmers have had increasing access to manufactured fertilizers, which has enabled them to continuously improve soil fertility and crop yields. Scientific research and the transfer of modern crop husbandry knowledge into practical applications have brought about huge improvements in agricultural productivity. As soil fertility has been built up, rural development and livestock production have become possible even in hilly areas that were previously impoverished. The current levels of soil fertility in Europe were built up mainly during the last few decades. Thanks to improvements in seed and in crop management, annual wheat yields are still increasing by about 100 kg a hectare on average. The good nutrient and organic matter content of many soils in the EU means that fertilizer input can be closely adapted to expected yields, resulting in the efficient use of inputs.

Manufactured fertilizers can be applied exactly when the crop needs nutrients the most, and the

amount

of

nutrients

applied

can

Development of fertilizer nutrient consumption in the EU (EFMA)

be

precisely controlled. Soil testing indicates the

Nutrient (million tonnes)

12

nutrient status of the soil, and farmers and advisory services are increasingly employing

10

specially developed computer programmes to 8

calculate nutrient needs. In addition, chemical and,

i n c re a s i n g l y,

optical

plant

analysis

6

methods are being applied. Many farms have 4

experience of using mineral fertilizers that stretches back more than thirty years.

After the decades spent on building up European

soil

f e r t i l i t y,

fertilizer

consumption

2 0 1925

1935

1945

N

1955

P2O5

1965

1975

1985

1995

2005

K2O

decreased drastically in 1992, when set-aside was introduced as a political instrument to control agricultural surpluses. It has continued to decrease as a result of increased efficiency in nutrient use – also from livestock sources – and

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SUSTAINABLE SOIL MANAGEMENT

because of continued progress in cropping systems. However, the trend towards reduced fertilizer use in European agriculture needs to be monitored closely, since in the longer term, nutrient deficiencies may affect the health and quality of crops as soils become exhausted.

On mined or abandoned areas, where there is often less plant cover and, as a result, less protection for the surface of the soil, soil fertility and soil structure may suffer further. Soil degradation and erosion problems could increase, especially in those southern European regions where it is less easy to achieve plant cover to protect the soil.

Using advanced techniques such as fertigation Drip irrigation, a technique that provides crops with water through special pipes at a high frequency but with a low volume of water (drips), can be combined with fertilizer a p p l i c a t i o n , t o o ff e r f e r t i g a t i o n . I t i s a t e c h n i q u e t h a t i s p a r t i c u l a r l y a p p ro p r i a t e i n d r y z o n e s , f o r e x a m p l e i n t h e Mediterranean region. Fertigation enables the farmer to meet the specific water and nutrient needs of the crops with great precision, thus minimising losses of both precious water and nutrients.

A beneficial side effect of fertigation is the avoidance of soil erosion and soil degradation, in that it eliminates the use of heavy machinery that can cause soil compaction. In addition, less water is needed to produce 1 kg of dry matter, since the water supply can be adapted to the speed of infiltration, thereby avoiding surface runoff and erosion. Fertigation allows cover crops or spontaneous vegetation to be grown in between rows of trees, with

positive

e ff e c t s

on

soil

conservation.

M o re o v e r,

this

technique facilitates the growing of trees on slopes, thereby making a further contribution to the prevention of erosion.

▲ Fertigation in Spain (water and nutrients are applied drip-wise through pipes).

In humid regions and areas with high rainfall, farmers work actively to maintain or improve the soil’s ability to ‘digest‘ water. Forming canals and installing drainage pipes to remove surplus

water are common technical solutions in northern Europe. In the dry regions of southern Europe, making use of irrigation and fertigation (i.e. combined irrigation and fertilizer application), improving water storage capacity, and covering the surface of the soil are techniques used to achieve efficient water management.

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Using appropriate cultivation methods Certain cultivation methods are useful as tools to combat soil erosion and other forms of soil degradation.

Strip Farming involves planting crops in widely spaced rows and filling in the spaces with another crop to ensure complete ground cover. In polyvarietal cultivation, the soil is planted with several varieties of the same crop. Harvest times vary for the different varieties of the crop, and since the entire field is not exposed all at once, the effects of erosion are greatly reduced. Trees or hedges can protect against mechanical damage and the drying effects of the wind.

The way in which a field is ploughed can also prevent erosion. With contour farming, the soil is tilled at right angles to the slope of the land. The resulting ridges act as dams, holding the water while it soaks into the soil and preventing it from running down the slope, taking soil with it. With terracing, fields are prepared for planting by levelling off areas on the slope to prevent the rapid run-off of water.

â–˛ Contour farming with maize.

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Through tillage the soil is disturbed prior to planting, and the timing of tilling can have a major effect on the amount of erosion that takes place during the year. If a field is ploughed in the autumn (and is therefore exposed to rain for long periods), erosion can occur all winter. However, if ground cover and the soil structure remain untouched until spring, the time in which erosion can occur is much shorter.

Minimum tillage encompasses a wide range of techniques, which include direct drilling of seed into stubble or pasture, spraying followed by direct drilling, spraying followed by a reduced number of soil tillage passes before sowing, and less frequent tilling. These management techniques leave substantial crop remains in the surface layer of the soil at times when there is little vegetation growth. This results in a more even soil surface, effectively reducing the risk of erosion. However, as a consequence, fertilizer applied to the soil surface may remain there for a long time exposed to wind or water erosion. Careful incorporation through ‘non-inversion tillage’, which disturbs the soil without inverting, may be advisable. ▲ Sugar beets grow in soil protected by mulch.

As can be seen, there is a wide variety of management techniques and options that can be used to help combat soil

degradation and maintain soil fertility. Using these techniques is clearly in the best interest of all European farmers, whose livelihood is only ensured if they are able to practise sustainable agriculture on healthy, fertile soils. Once farmers are aware of the potential problems associated with soil degradation, they are keen to follow agricultural practices that reduce the risk.

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CONCLUSION Europe’s soils are a precious and limited non-renewable resource. Thanks to the area’s favourable climate and location, and the advanced farming techniques of the European agricultural community, the soils of Europe are extraordinarily fertile, providing us with high yields in a variety of high quality food products. The provision of sufficient quantities of high quality food has been based on the development and maintenance of the soil’s fertility, and this fertility must be maintained if the quality and quantity of our harvests is to be sustained in the future. The prevention of any form of soil degradation is a major responsibility for both Europe as a community and for its farmers, as solutions to regional and even global environmental problems are connected with sustainable agricultural soil management. This document seeks to inform all those with an interest in and a commitment to European agriculture about the problems associated with soil degradation and about the solutions to those problems. Since tools to maintain soil fertility can also prevent soil degradation, fertilizers, as an essential element of soil fertility, have an important role to play in the solutions suggested.

Seven steps towards achieving sustainable soil management:

1. Recognise the importance of healthy, fertile soils 2. Assess the condition of soils throughout Europe 3. Identify site-specific problems 4. Identify site-specific solutions 5. Implement solutions/modify land management practices 6. Devise a system of incentives and support programmes to ensure that farmers achieve sustainability goals 7. Monitor progress

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Alexander, E.B. (1988): Rates of soil formation: Implications for soil loss tolerance. Soil Science 145 (1), 37-45. Botschek, J., Sauerborn, P., Skowronek, A., Wolff, R. (1997): Tolerierbarer Bodenabtrag und Bodenneubildung – Konzepte und Perspektiven. Mitteilungen der Deutschen Bodenkundlichen Gesellschaft 83, 87-90. Dowdeswell, E. (1998): Extent and impacts of soil degradation on a world-wide scale, in : Towards Sustainable Land Use. Furthering Cooperation Between People and Institutions, VOLUME I, Advances in Geoecology 31. H.P. Blume, H. Eger, E. Fleischhauer, Hebel, C. Reij, K.G. Steiner (Editors). – Reiskirchen: Catena-Verl. ISBN 3-923381-42-5. European Environment Agency (1998): Europe’s Environment: The Second Assessment. Eurostat. European Commission (2000): Communication from the Commission to the Council and the European Parliament. Indicators for the Integration of Environmental Concerns into the Common Agricultural Policy COM(2000) 20 final. European Commission (1999): Directions towards sustainable agriculture. Com(1999) 22 final. European Commission (1999): Report - Agriculture, environment, rural development - Facts and Figures - A Challenge for Agriculture. ISBN 92-828-7676-4. European Conservation Agricultural Federation ECAF (1999): Conservation Agriculture in Europe: Environmental, Economic and EU Policy Perspectives. Brussels, 1999. European Fertilizer Manufacturers Association EFMA (1997): Code of Best Agricultural Practice: Nitrogen. European Fertilizer Manufacturers Association EFMA (2000): Forecast of Food, Farming and Fertilizer use in the European Union, 2000 to 2010 European Fertilizer Manufacturers Association EFMA (2000): Urea. Code of Best Agricultural Practice. European Union (1999): Council Decision 26 March 1999. AGENDA 2000. European Society for Soil Conservation (2000) : Third International Congress on 28 March-1 April, 2000. Man and Soil at the Third Millennium, Key Notes, (Valencia (Spain). José L. Rubio, S. Asins, V. Andreu, José M. de Paz, E. Gimeno (Editors) Food and Agriculture Organisation of the United Nations (2000): 50 years of agricultural statistics by FAO 1950-1999. Statistics Division. Friend, J.A. (1992): Achieving soil sustainability. Journal of Soil and Water Conservation 47, 156157. German Advisory Council on Global Change (1995): World in Transition: The Threat to Soils. Economica Verlag, Bonn. ISBN 3-87081-055-6

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Gregorich, E.G., Greer, K.J., Anderson, D.W., and B.C. Liang (1998): Carbon distribution and losses: Erosion and Deposition effects. Soil & Tillage Research 47, 291-302. Johnston, A.E. and I. Steén (2000): Understanding Phosphorus and its Use in Agriculture. European Fertilizer Manufacturers Association EFMA (in print). Laegreid, M., Bockman, O.C. and O. Kaarstad (1999): Agriculture, Fertilizers and the Environment. ISBN 0 85199 358 3. Rex, M. (1997) : Yields and botanical developments of permanent grassland in the Middle Black Forest as an effect of longterm mineral fertilization. In : Boden und Landschaft. Schriftenreihe zur Bodenkunde, Landeskultur und Landschaftökologie, Band 17, 77-90, 1997. Felix-Henningsen, P. und Wegener, H.-R. (Editors). Rubio, J.L. and E. Bochet (1998): Desertification indicators as diagnosis criteria for desertification risk assessment in Europe. Journal of Arid Environments 39: 113-120. Scherr, S.J. (1999): Soil Degradation - A Threat to Developing Country Food Security by 2020? Food, Agriculture, and the Environment Discussion Paper 27. International Food Policy Research Institute. ISBN 0-89629-631-8. Semmel, A. (1995): Holozäne Bodenbildungsraten und "tolerierbare Bodenerosion" – Beispiele aus Hessen. Geol. Jb. Hessen 123: 125-131. United Nations (1992): United Nations Conference on Environment and Development (UNCED) held in Rio de Janerio, Brazil, 3 to 14 June 1992. Agenda 21. Rio Declaration on Environment and Development. United Nations Environment Programme (1999): Global Environment Outlook 2000. Earthscan Publications Ltd, London. Werner, W. (1997): Implementation and Efficiency of Counter-measures against Diffuse Nitrogen and Phosphorus Input into Groundwater and Surface Waters from Agriculture, (75-88), in: Controlling Mineral Emissions in European Agriculture. CAB International. E. Romstad, I. Simpson and A. Vatn (Editors)

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European Fertilizer Manufacturers Association

Avenue E. van Nieuwenhuyse 4 B-1160 Brussels Belgium Tel + 32 2 675 35 50 Fax + 32 2 675 39 61 E-mail main@efma.be For more information about EFMA visit the web-site www.efma.org


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Acknowledgements EFMA wishes to express its ackowledgments to individuals and companies for making this publication happen. We wish to thank in particular the 'Erosion Working Group' consisting of Dimitrios Analogides (PFI), Peter Botschek (EFMA), SebastiĂ n Ruano (Fertiberia), Jane Salter (FMA) and Hartmut Wozniak (SKW). Additional support came from Amazone, Johannes Botschek (University Bonn), BASF, Fertiberia and SKW Piesteritz. Help in editing came from Penelope Ă–rtliBarnett (eels). Design and printing Altitude Graphic, rue Saint-Josse 15, 1210 Brussels, (32 2 223 70 55), www.altitude.be

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