In many countries, agriculture is the largest form of land use; farmland habitats account for a great percentage of natural habitats. Protected areas are not sufficient for nature conservation, especially for migratory species (e.g. birds) because surrounding habitats are agricultural lands which often create negative externalities. Agriculture, especially in its most extreme modern form of industrialized monoculture, modifies landscapes and damages the ecosystem's goods and services, including biodiversity at all levels. Agricultural encroachment, as well as pollution and intensification are responsible for contributing to soil and water degradation and to the extinction of biodiversity.
Current approaches to ecological agriculture such as integrated pest management, integrated plant nutrition systems and conservation tillage, consider only one aspect of the farming system components: pest ecology, plant ecology and soil ecology, respectively. The ability to define strategies that combine these and other management elements into a single approach is proper to organic agriculture. Organic management focuses on the food web relations and element cycling and aims to maximise the agro-ecosystem's stability and homeostasis.
Organic agriculture, through its systemic approach and avoidance of agro-chemicals, prevents natural resource degradation and the loss of land and productive potential. In organic agriculture, nature is both instrument and aim. As organic farmers cannot use synthetic substances (e.g. fertilizers, pesticides, pharmaceuticals) they need to restore the natural ecological balance because ecosystem functions are their main productive "input". For example:
As organic farmers cannot use synthetic substances (e.g. fertilizers, pesticides, pharmaceuticals) they need to restore the natural ecological balance because ecosystem functions are their main productive "input".
The ecosystem approach is a strategy for the integrated management of land, water and living resources that promotes conservation and sustainabe use in an equitable way. An ecosystem approach is based on the application of appropriate scientific methodologies focused on levels of biological organization, which encompass the essential structure, processes, functions and interactions among organisms and their environment. It recognized that humans, with their cultural diversity, are an integral component of many ecosystems. The ecosystem approach requires adaptive management to deal with the complex and dynamic nature of ecosystems and the absence of complete knowedge or understanding of their functioning. Ecosystem processess are often non-linear and the outcome of such processes often shows time-lags. The following 12 principles of the ecosystem approach are complementary and interlinked: |
Principle 1:The objectives of management of land, water and living resources are a matter of societal choice. |
Principle 2:Management should be decentralized to the lowest appropriate level. |
Principle 3:Ecosystem managers should consider the effects (actual or potential) of their activities on adjacent and other ecosystems. |
Principle 4:Recognizing potential gains from management, there is usually a need to understand and manage the ecosystem in an economic context. Any such ecosystem-management programme should: (a) reduce those market distortions that adversely affect biological diversity; (b) align incentives to promote biodiversity conservation and sustainable use; (c) internalise costs and benefits in the given ecosystem to the extent possible. |
Principle 5:Conservation of ecosystem structure and functioning, in order to maintain ecosystem services, should be a priority target of the ecosystem approach. |
Principle 6:Ecosystems must be managed within the limits of their functioning. |
Principle 7:The ecosystem approach should be undertaken at the appropriate spatial and temporal scales. |
Principle 8:Recognizing the varying temporal scales and lag-effects that characterise ecosystem processes, objectives for the ecosystem management should be set for the long term. |
Principle 9:Management must recognize that change is inevitable. |
Principle 10:The ecosystem approach should seek the appropriate balance between, and integration of, conservation and use of biological diversity. |
Principle 11:The ecosystem approach should consider all forms of relevant information, including scientific and indigenous and local knowledge, innovations and practices. |
Principle 12:The ecosystem approach should involve all relevant sectors of society and scientific discipline. |
Source: Convention on Biological Diversity, 2002 (Decision V/6) |
The direct economic value of ecosystem functions for organic farmers is an excellent example of "benefit-sharing". To master ecosystem functions in order to produce decent high-quality yields, adaptive management practices are crucial: growing conditions in organic agriculture are neither optimal, static nor predictable. Farmers must become excellent observers and must be trained to react flexibly, often intuitively and appropriately to the local context. In contrast, other farming methods try hard to condition the environment of the plants for optimal growing conditions by using a wide range of inputs. Moreover, most recommendations and fertilization and spraying programmes are highly standardized and not site-specific.
Organic agriculture is an approach, which is not confined to production alone. Intersectoral cooperation between farmers, environmentalists, processors and traders, quality controllers and consumers is a very common characteristic of organic agriculture.
Doherty et al. (2000) described sustainable agriculture as "ecological engineering solutions aiming to minimally manipulate and manage ecosystems for the benefit of both nature and humanity". To date, no ecological farming scheme other than the organic one has succeeded in providing ecosystem functions and socio-economic goods in a comparably equitable way.
As the central basis for all agricultural activity, soil is one of the chief natural resources. Since organic farmers cannot compensate for a loss in soil fertility by inputs of synthetic nutrients, the building and maintenance of soil fertility is a central objective of organic agriculture2. The impact of organic agriculture on soil properties has been covered extensively by research with a special focus on the relevant parameters of organic matter content, biological activity and soil erosion.
The environmental importance of organic matter content is its capacity to limit physical damage and to improve nutrient availability as well as biological activity. Research on organic matter concentrates on measuring the soil organic carbon content parameter.
The review of relevant research conducted by Stolze et al. (2000) concludes that under European conditions organic agriculture has beneficial effects on the characteristics of soil organic matter because the soil organic carbon content is higher on organically farmed soils than on conventional ones. Fertilization in organic agriculture is based on organic substances such as farmyard manure, compost, green manure, plant residues and commercial organic N-fertilizers. Consequently, there is an extensive supply of organic matter passing through aerobic decomposition processes.
Mineralization and decomposition processes are influenced by humidity, temperature and oxygen. Under humid tropical conditions these processes run faster and all year round, whereas under temperate conditions they are slower and come to a halt during the colder months. Soil type also plays a role. Sandy soils dry out quickly, slowing down the decomposition process, ferralitic soils on the other hand are generally not very fertile, but they encourage fast decomposition and the building-up of stable organic matter.
Intense biological activity promotes metabolism between soil and plants and should be a focus of sustainable plant production and fertilizer management. In contrast to conventional agriculture, organic farmers depend more on a high and sustained supply of organic substances including crop rotations with clover/grass ley, underseeds, catch crops, green and animal manure. Under European conditions, organic agriculture performs better than conventional agriculture with regard to certain parameters: for example, 30 to 100 percent higher microbial activity3 and a significantly higher biomass (+30 to 40 percent), density (+ 50 to 80 percent) and species diversity of earthworms, a key soil-macro faunal species4.
Box 2: The ecosystem approach to environmental restoration in Malleco, Chile A restauration and environmental education project was undertaken in four communities, (Collopulli, Lumaco, Purén and Ercilla) in the province of Malleco, 600 km to the south of Santiago de Chile between 1994 and 1998. The four communities cover an area of approximately 3 000 km2, forming part of the dry interior zone of the province. Mean annual precipitation is 800 to 1200 mm, and temperatures vary between 10°C and 27°C. Felling of native forests in this region, burning of the land and cereal monocultures have led to a continued destruction and alteration of the structure and function of the ecosystem. As a result of deforestation, consequent erosion and a breakdown in the water cycle, crisis point was reached in 1990 when it was realised that 14000 km2 was suffering extreme ecological degradation. This was compounded by heightened social tensions due to the establishment of a forest monoculture of Eucaliptus globulus and Pinus radiata in land that historically belonged to indigenous communities. Low levels of productivity were a direct result of these conditions, but also as a consequence of low levels of organic matter in the soil (between 0.3 and 1 percent), acidity (pH fluctuating between 4.5 and 5) and low biodiversity (only 2 to 7 plant species were found in the agricultural systems and only 1 to 8 species in the forest systems). The project aimed to improve the quality of life for the population by creating more stable local economies, greater food security, improved gender relations and increased social capital. This was to be achieved through training and education and through the integration of organic agriculture into the degraded traditional agricultural systems, focusing on the conservation and improvement of the soil and increasing biodiversity. In total over 850 families received training on the management of natural resources and organic agriculture given by agricultural technicians from NGOs and municipal and public organizations in collaboration with the Centre for Education and Technology. The participating families had on average six members owning plots of land that varied between 0.2 and 13.6 ha. One of the biggest problems facing the people of Malleco was that of soil erosion, over 60 tonnes/ha of soil was being lost per year. Erosion control measures were introduced, including a system of ditches and living barriers. These helped to maintain soil humidity and improve the structure and stability of the soil, leading to the eventual formation of terraces. Crop productivity and diversity were increased through the use of crop rotations, incorporating fallows and leguminous cover crops. The introduction of trees to form agroforestry systems provided sources of firewood, timber, fruits and shade, but also helped in erosion control, protecting water courses through the stabilization of the soil and as wind breaks, regulating the velocity of the winds. Pest and disease control was achieved entirely through biological control and crop rotations. Of particular success was the use of fungi antagonistic to soil pathogens from the genus Trichoderma and the use of fungal spores from the genus Beauveria for control of the corn earworm, a major pest of maize. |
Indicators |
1994 |
1998 |
Land erosion |
60 tonne/ha |
12 tonne/ha |
Organic material |
2.1% |
3% |
Water/humidity retention |
8% |
11% |
Biodiversity (Shannon index) |
1 |
2.28 |
Aluminium saturation |
4.8 |
2.4 |
Sum of bases (magnesium, calcium and sodium) |
5.75 |
8.8 |
By the end of the project (1998), many changes were apparent. Organic management practices had led to substantial erosion control and improvements in soil structure and fertility (see table below). The consequent improvements in soil water retention, reduction in erosion and the introduction of crop rotations resulted in a greater variety in the food and fodder stuffs grown and an increase in their yields (approximately 20 percent for cereals and between 20 and 60 percent for horticultural crops). The area devoted to horticultural crop activities was also enlarged by 260 percent and as a result, incomes increased significantly from approximately US$1300/ year in 1994 to over US$6000/year in 1997. In 1994 land use and income derivation was primarily focused on animal production and collecting activities (e.g. firewood and fruits). However, by the end of the project this focus had turned to horticultural production which began to contribute up to 77 percent of the family income. This is important as, at the onset of the project, only products from animal production (managed mainly by men) were destined to market. Crops grown by women were only a small contribution to the family economy. This change in land use and income generation has had an important impact on the position of women both within the family and the community. The introduction of erosion control together with organic agriculture techniques had important impacts on the livelihoods of the participating communities, but was also a driving factor in the restoration of degraded environments. This project demonstrates how organic agriculture can become an important link between natural resource conservation and community development. Source: provided to FAO by Consorcio Latinoamericano sobre Agro-ecología y Desarrollo (CLADES), Chile. |
Soil is a habitat for plants, animals and micro-organisms. As plants build up organic matter, soil animals feed on them and their debris, whilst microbes decompose the complex organic compounds to their mineral components and to carbon dioxide. A living soil is central to soil fertility because it is the activity of soil organisms that makes available the elements in plant residues and organic debris entering the soil. Part of this material, however, remains in the soil and contributes to its stabilization by humus build-up.
Various research results show that the activity of micro-organisms is higher in organically- than in conventionally-managed soil. As a consequence, in organically managed soils, nutrients are recycled faster and soil structure is improved. For example, Fliessbach et al. (2001) found in Switzerland up to 90 percent higher total mass of micro-organisms in organically managed soils. As for soil fungi, Elmholt (1996) found a higher number and abundance of saprophytic soil fungi with a higher potential of decomposition of organic material. Mycorrhizae, important representatives of soil fungi, live as symbionts with plant roots. The degree of mycorrhizal root colonization was found to be distinctly higher in organic plots as compared to conventional plots5.
As mineralization processes proceed much faster on ferralitic soils in the tropics and subtropics than on soils typical to temperate and continental zones, a high organic matter content and high biological activity are the pre-requisite for sustainable soil fertility. The positive impacts of organic agriculture on biological activity, micro-organisms and soil organic matter content reported in the paragraphs above are therefore also valid for soils in the tropics and subtropics.
Soil erosion is assumed to be the main cause of soil degradation around the world. The loss of fertile top soil by erosion results in a lower yield capacity on the onehand and in a undesired transfer of nutrients, pesticides and sediments in surface water on the other.
Reganold et al. (1987) found during a long-term comparison (since 1948) of soils from selected conventional and organic farms of the same soil type near Spokane in Washington, USA, that topsoil was 16 cm thicker on organically managed plots. This was most probably due to inclusion of a green manure legume crop in the third year of rotation and fewer tillage operations on the organic field. The organically-farmed soil not only had deeper topsoil but also significantly higher organic matter content and suffered less soil erosion than the conventionally farmed soil. The authors concluded that the organic agriculture system was more effective than the conventional agriculture system in reducing soil erosion and in maintaining soil productivity.
Generally, organic soil management techniques such as organic fertilization, mulching and cover cropping improve soil structure and therefore increase the soil's water infiltration and retention capacity, substantially reducing the risk of erosion. These management techniques are also of special relevance on porous ferralitic soils of the tropics and subtropics which are highly susceptible to soil erosion due to frequent heavy rainfall.
A thorough comparison of relevant soil parameters on conventionally- and organically-managed soils is provided by the long-term DOC-trial6 carried out by the Swiss Research Institute of Organic Farming (FiBL). The results of the DOC trial can be summarized as follows:
Organic soil management improves soil structure by increasing soil activity, thus reducing the risk of erosion.
The detrimental effects of intensive agriculture on ground and surface water are largely due to erosion and to nitrate and pesticide pollution. The chief threats to water quality posed by agriculture are: high organic fertilization levels in combination with high stocking rates, the excessive application of mineral N-fertilizers; the lack of a protective soil cover; narrow crop rotations and frequent tillage; high levels of available nitrogen after harvest, and contamination of water with synthetic pesticides.
As organic agriculture uses no synthetic pesticides, there is no risk of synthetic pesticide pollution of ground and surface waters. As regards nitrate leaching, Table 1 summarizes research results on rates of nitrate leaching in Germany and the Netherlands. It shows that under western European conditions nitrate leaching rates per hectare are significantly lower in organic agriculture than in conventional agriculture systems.
The reasons for the lower nitrate leaching rates in organic agriculture are the ban on mineral N-fertilizers and lower livestock densities. These constraints set up by the organic agriculture standards lead to nitrogen on organic farms nitrogen being - in economic terms - a quantitatively scarce factor. The economic consequences of nitrogen being scarce on organic farms are quite impressive: the opportunity costs (cost of producing on-farm) of 1 kg nitrogen on organic farms can amount to seven to sixteen times the cost of mineral N-fertilizers8. So it is not surprising that in contrast to conventional farms where manure and slurry are often a waste problem, organic farmers are forced to develop efficient nitrogen management strategies like intercropping, catch cropping, optimal ploughing-in of legume crops or limiting the use of liquid manure to avoid nitrogen losses.
As a result, in some regions of Germany and France, waterworks subsidise conversion to organic agriculture in water protection areas as an economically efficient solution for reducing the cost of cleaning-up drinking water by minimising the nitrate and pesticide contamination of groundwater.
Table 1: Nitrate leaching rates per hectare from organic agriculture compared to conventional agriculture systems | |
Reduction of nitrate leaching rates in organic agriculture compared to conventional agriculture |
Authors |
> 50% |
Smilde (1989) |
> 50% |
Vereijken (1990) |
57% |
Paffrath (1993) |
40% (sand) / 0% (loam) |
Blume et al. (1993) |
50% |
Reitmayr (1995) |
40% |
Berg et al. (1997) |
64% |
Haas (1997) |
Source: Stolze et al., 2000, expanded |
|
Waterworks subsidise conversion to organic agriculture in water protection areas as an economically efficient solution for reducing the cost of cleaning-up drinking water by minimising the nitrate and pesticide contamination of groundwater.
While scientific results from other climatic zones are scarce, positive effects of organic agriculture on the nitrate leaching risk can be reported from a citrus farm in Cuba. Under organic fertilization management based on compost with 60 kg available N per ha, the farm achieved exactly the same yield level as under conventional fertilization management with 200 kg of mineral N. This example shows that organic fertilization management can help reduce the risk of nitrate leaching especially under extreme climatic conditions9.
An adequate and balanced supply of nutrients in the soil is essential for several reasons. Nutrient surpluses might result in nutrient losses which could subsequently lead to water and air contamination and eutrophication. However, nutrient deficiency is synonymous with the over-exploitation of soil nutrients in the long run, which consequently leads to a decrease in yield and crop quality.
Research by Freyer (1997) in Switzerland shows that only 14 percent of all organic farms have an N-surplus, and only 1.5 percent had a P-surplus. Most of the organic farms have a negative N- and P-balance. Results from different European countries comparing phosphorous and potassium balances of conventional and organic farms are presented in Table 2: even though the ranges from study to study vary a great deal, it can be concluded that the phosphorous and potassium surpluses of organic farms are significantly lower than on conventional ones.
Table 2: Examples for P, K balances (kg/ha) comparing organic with conventional farms from different European countries | ||||
P balance (kg/ha) |
K balance (kg/ha) | |||
Organic |
Conventional |
Organic |
Conventional | |
Sweden |
-12 |
+37 |
-4 |
+39 |
Netherlands |
||||
Cash crop farm |
+18 |
+23 |
+31 |
+25 |
Horticulture |
+32 |
+60 |
+119 |
+110 |
Dairy farm |
+8 |
+31 |
- |
- |
Germany |
||||
Mixed farm |
-4 |
+13 |
-27 |
+31 |
Dairy farm* |
-2 |
+5 |
+7 |
+20 |
Source: Stolze et al., 2000, modified and * Haas et al., 2001 | ||||
Due to negative nutrient balances as shown in Table 2, the question arises whether organic agriculture methods cause gradual loss of soil minerals. First of all, the proportion of soluble nutrients is lower on organically-managed soils. On the other hand, Mäder et al. (2000) found no decrease in organic yields as an indicator for nutrient deficiency on farms which are managed organically for more than 30 years. As discussed later, higher biological activity and higher mycorrhizal root colonization counteract nutrient deficiency, thus as Oberson et al. (2000) state, for phosphorus, the aim of organic agriculture of increasing nutrient supply through increased biological activity has been achieved.
Higher biological activity and higher mycorrhizal root colonization counteract nutrient deficiency.
Energy consumption in agriculture includes the direct consumption of fossil energy (e.g. fuel and oil), as well as indirect energy consumption (e.g. from the production of synthetic fertilizers and pesticides). Leaving aside indirect agricultural energy consumption, OECD statistics indicate that agriculture contributes only 2 percent to total direct energy used in OECD countries. Nevertheless, limited fossil energy resources and the climatic relevance of its use require efficient energy use, even in agriculture. Relevant parameters for evaluating energy use in agriculture are energy consumption and energy efficiency.
Considering both, direct and indirect energy consumption, scientific calculations on energy consumption per hectare indicate that organic farms use less energy than conventional farms: several researchers10 calculated the energy consumption of organic farms to amount 64 percent of that on conventional farms. Other recent research11 confirms the figures mentioned above at lower levels, with energy consumption on organic farms amounting to 45 percent or 30 to 50 percent of conventional farms, respectively.
Table 3 below shows figures on energy consumption (GJ) both per hectare and per unit of output (t) for different crops, comparing organic and conventional agriculture systems in Germany, Italy, Sweden and Switzerland. The determining factor for energy consumption of a specific crop is cropping management, which includes tillage intensity, manuring and weed control. On a per hectare scale, all authors determined lower energy consumption on organic farms. For organic potatoes and apples, however, energy consumption per output unit is higher relative to conventional production. This is the result of higher energy input for mechanical measures like weed control in organic production and of lower mineral N-fertilization use in conventional production.
A second parameter appropriate for evaluating energy use is energy efficiency. It provides information about the ratio of energy input and output. Comparing rotations of different production systems in Iran, Zarea et al. (2000) found the energy efficiency of organic agriculture to be 81 percent better compared to high-input conventional agriculture. In a similar investigation in Poland Kus & Stalenga (2000) calculated a 35 percent higher energy efficiency of organic compared to conventional agriculture. Under Mediterranean conditions in Italy, a 25 percent higher efficiency in organic wheat and an 81 percent higher efficiency in organic vineyard production systems were found12.
Even though the ban on synthetic pesticides might lead to higher fuel consumption on organic farms due to increased mechanical weed control13, research results presented below show that with respect to energy consumption, organic agriculture is performing better than conventional agriculture. The main reasons for this are:
With respect to energy consumption, organic agriculture is performing better than conventional agriculture.
Table 3: Calculations of energy consumption of different products | ||||||
Product |
Energy use GJ/ha |
Energy use GJ/t | ||||
Conventional |
Organic |
as % of conventional |
Conventional |
Organic |
as % of conventional | |
Winter wheat |
||||||
Alföldi et al. (1995) |
18.3 |
10.8 |
-41 |
4.21 |
2.84 |
-33 |
Haas and Köpke (1994) |
17.2 |
6.1 |
-65 |
2.70 |
1.52 |
-43 |
Reitmayr (1995) |
16.5 |
8.2 |
-51 |
2.38 |
1.89 |
-21 |
Potatoes |
||||||
Alföldi et al. (1995) |
38.2 |
27.5 |
-28 |
0.07 |
0.08 |
+7 |
Haas and Köpke (1994) |
24.0 |
13.1 |
-46 |
0.08 |
0.07 |
-18 |
Reitmayr (1995) |
19.7 |
14.3 |
-27 |
0.05 |
0.07 |
+29 |
Citrus |
||||||
Barbera and La Mantia (1995) |
43.3 |
24.9 |
-43 |
1.24 |
0.83 |
-33 |
Olive |
||||||
Barbera and La Mantia (1995) |
23.8 |
10.4 |
-56 |
23.8 |
13.0 |
-45 |
Apple |
||||||
Geier et al. (2001) |
37.35 |
33.8 |
-9.5 |
1.73 |
2.13 |
+23 |
Milk |
||||||
Cederberg and Mattsson (1998) |
22.2 |
17.2 |
-23 |
2.85 |
2.41 |
-15 |
Wetterich and Haas (1999) |
19.1 |
5.9 |
-69 |
2.65 |
1.21 |
-54 |
Source: Stolze et al., 2000, expanded | ||||||
Year |
System |
Before cultivation |
After harvest | ||
OM (g/kg) |
Total N (g/kg) |
OM (g/kg) |
Total N (g/kg) | ||
2nd |
Organic |
21.3 |
1.50 |
18.1 |
1.42 |
Non-organic |
20.6 |
1.50 |
15.9 |
1.47 | |
3rd |
Organic |
20.0 |
1.33 |
22.1 |
1.41 |
Non-organic |
16.2 |
1.32 |
16.6 |
1.36 | |
Although the organic system initially required higher financial outlays, principally as a consequence of the greater demand for labour, larger returns were made on this labour than in the non-organic system. However, this study has also shown that there are many advantages to organic strawberry production in terms of increased yields, energy efficiency and economic returns. Source: Xi et al., 1997 |
However, higher labour requirements may be expected on organic farms under European conditions14 due to a higher share in the production of labour intensive crops (e.g. vegetables) and on-farm marketing and processing activities. Arable crops also demand greater labour inputs, for example, for mechanical weeding.
In Europe, figures for labour use on organic farms in relation to comparable conventional farms vary between countries and studies15. Most commonly, labour use per hectare of utilized agricultural area is on average 10 -20 percent higher on organic farms. In a European context, the labour input is higher on organic arable and mixed farms, while organic dairy farms use the same amount of labour, or less, than comparable conventional farms. On horticultural farms, labour requirements are much higher than on conventional farms. Few data exist on pig and poultry farms, but labour per hectare of utilized agricultural area seems to be similar to conventional farms, as livestock density is reduced.
For hundreds of years, agriculture has contributed substantially to the diversity of species and habitats, and agriculture has formed many of today's landscapes. Over the last century, however, modern intensive agriculture, with its high input of synthetic pesticides and fertilizers and monocrop specialization, has been detrimental to the diversity of genetic resources of crop varieties and livestock breeds, to the diversity of wild flora and fauna species and to the diversity of ecosystems. The 2000 IUCN Red List of threatened species highlights habitat loss as the main threat to biodiversity, with agricultural activities affecting 70 percent of all threatened bird species and 49 percent of all plant species16.
Because of the increasing loss of agricultural biodiversity on a global scale, the Convention on Biological Diversity has developed a work programme on this subject in 1996. This programme states inter alia that farming practices that stop degradation while restoring and enhancing biological diversity should be encouraged, including organic agriculture17.
Organic agriculture is dependent upon stabilizing agro-ecosystems, maintaining ecological balances, developing biological processes to their optimum, and linking agricultural activities with the conservation of biodiversity. Wild species perform a variety of ecological services within organic systems: pollination, pest control, maintenance of soil fertility. Thus, higher levels of biodiversity can strengthen functions essential for farming systems and therefore, agricultural performance. Enhancing functional biodiversity is a key ecological strategy to bring sustainability to production on organic farms. Organic systems also use substantially fewer external inputs and do not use synthetic chemical fertilizers, pesticides, genetic modified organisms and pharmaceuticals. Instead, systems are designed to work in harmony with nature in order to determine agricultural yields and disease resistance. By respecting the natural capacity of plants, animals and the landscape, organic agriculture aims to optimize quality in all aspects of agriculture and the environment.
Biological pest control on organic farms, for example, relies on maintaining healthy populations of pest predators and parasitoids. A study in California comparing conventional with organic tomato fields showed a higher abundance of natural enemies and greater richness of species in organic tomato fields. There was no significant difference for any type of damage to tomato foliage or fruit, showing that the organic system achieves the same levels of pest control without having to apply synthetic chemical pesticides18.
Organic agriculture is thus committed to the conservation and enhancement of biodiversity within agricultural systems, both from a philosophical perspective and from the practical viewpoint of maintaining productivity. To this end, the importance of biodiversity as part of a well-balanced organic system is part of the IFOAM International Basic Standards for Organic Agriculture Production and Processing.
Numerous scientific studies, mainly from Europe and North America, give evidence that on organic farms biodiversity is higher than that on conventional and farms. Biodiversity is generally assessed at three distinct levels19:
These levels of biodiversity have been used in the following sections to show the links between biodiversity and organic agriculture.
In general, the degree of biodiversity in agro-ecosystems depends on four main characteristics of agro-ecosystems20:
Higher crop diversity on organic farms
Since organic farms are mostly mixed farms, integrating animal husbandry with crop production, using vast and diverse rotations, intercrops and green cover crops, and maintaining soil fertility by cultivating nitrogen fixing legumes, they display a higher diversity of domesticated species than conventional farms .
Hausheer et al. (1998) evaluated crop rotations on 110 organic, integrated and conventional farms in a Swiss pilot farm project. They found more diverse crop rotations (4.5 different crops in organic as opposed to 3.4 different crops in integrated farming) and a higher number of crops, including perennials, vegetables and herbs (10.2 in organic and integrated farms; 7.4 in conventional farms).
Today, the adoption of high-yielding, uniform cultivars and varieties has led to a considerable reduction in the number of plants and animals used in agriculture. Only 120 cultivated plant species and 14 mammalian and avian species provide 90 percent of human food supply.
Evidence of the trend towards monoculture and uniformity is given by the fact that in India, under the Green Revolution, the number of cultivated rice varieties has decreased from more than 100 000 to 10; also, 50 percent of the goat breeds, 20 percent of the cattle breeds and 30 percent of the sheep breeds are in danger of extinction21. In Mexico, only 20 percent of the maize varieties reported in 1930 are now known. In China, nearly 10 000 wheat varieties were used in production in 1949; by the 1970s, only about 1000 remained in use22. This trend is just as visible in animals: 740 animal breeds became extinct during the twentieth century. Currently, 1350 breeds face extinction, with two breeds being lost each week23.
Organic producers look for productive varieties suited to their local climatic and soil conditions and that are not susceptible to disease and pest attack.
Organic producers look for productive varieties suited to their local climatic and soil conditions and that are not susceptible to disease and pest attack. Organic agriculture standards recommend the cultivation of site adapted crop varieties24, characteristics often found in the older native cultivars. This, however, does not necessarily mean that organic agriculture sets narrow limits to the use of modern maximum yield varieties, which are often chosen for pest/disease resistance purposes. Still, the preservation of native varieties and breeds is an important initiative of the organic movement, but their actual use depends on individual farmers.
Many seed banks and indigenous variety conservation programmes worldwide are linked to organic agriculture projects. For instance, the Sustainable Agriculture and Rural Development Project in Kenya is working with communities in the Gilgil district to develop organic systems to increase food security through a community indigenous seed conservation programme. Indigenous seeds have been shown to perform better in the harsh drought conditions25.
Apart from the adoption of high-yielding, uniform cultivars, a further possible threat to genetic diversity, and biodiversity in general, are the side-effects of the release of genetically engineered organisms into the environment.
Genetically engineered plants designed to control pests can have negative side-effects on beneficial insects and further non-target organisms as well. Oilseed rape with genetically induced resistance to insects has been reported to damage beneficial insects such as honey bees26. The use of herbicide resistant plants can result in greater use of herbicides, increasing the negative effects of intensive farming on natural biodiversity. Furthermore there is the danger that transgenic plants could become feral and thus suppress indigenous flora. Feral oilseed rape populations in Canada are resistant to three herbicides and have become one of the most troublesome weeds27.
Indicators |
Pumpkin breeding before the special period (1980s) |
Pumpkin breeding under conditions of the special period (1990s) |
Mineral fertilisation (kg ha-1) |
Nitrogen: 42 |
0 |
Phosphorus: 39 |
||
Potassium: 62 |
||
Organic soil amendments |
Rarely applied |
Typically 6-7 tonnes ha-1 |
Frequency and amount of artificial irrigation (summer season) |
9-11 times season-1 2000 m3 ha-1 |
2-4 times season-1 200m3 ha-1 |
Varietal maintenance and seed multiplication |
Isolation |
Cross pollination |
Pest and disease control |
Agrochemical intensive |
Biological |
Use of honey bees |
Sporadically |
Frequently |
Yield |
6-8 tonnes ha-1 |
6-8 tonnes ha-1 |
Farmer participation |
Contracted seed production |
On farm selection of half sib families |
Researcher participation |
Screening germplasm and |
Screening germplasm, facilitating |
Energy requirements (kcal ha-1) |
Fertilisation: 679 000 |
Fertilisation: 42 000 |
Irrigation: 10 160 000 |
Irrigation: 3 697 200 | |
Pesticides: 6 160 000 |
Pesticides: 88 000 | |
Total: 16 999 000 |
Total: 3 827 200 | |
Source: Labrada, 2002, modified. | ||
Recently, it was reported that transgenic DNA introgressed into traditional maize landraces in Oaxaca, Mexico28. Concerns have been raised about the potential effects of transgenic introductions on the genetic diversity of crop landraces and wild relatives in areas of crop origin and diversification, as this diversity is considered essential for global food security.
Insofar as organic agriculture is dependent upon maintaining ecological balances and diverse agro-ecosystems, genetic engineering is a contradiction to the principal aims of organic agriculture. Organic agriculture does not allow genetic engineering in its standards as genetic engineering focuses on genetic makeup without taking into account the complete organism or farming system in which the organism functions.
Floral diversity has been shown to contribute to ecosystem stability, while the invertebrate community associated with field boundaries performs many ecosystem functions including biological control of pests and diseases, pollination and food resource for higher trophic levels.
Today, the diversity of the typical wild flora on arable fields, which is the main habitat for a wide range of species, is at risk. Many species are endangered due to agricultural intensification, including the intensive use of mineral fertilizers and of herbicides, intensive soil management and the destruction of habitats. In grassland species, diversity is also decreasing due to intensification of grazing management and to high inputs of fertilizers.
Whereas in conventional agriculture weeds are considered competitive to the crop and are eliminated by herbicides, in organic systems some of the accompanying plants are desired to a certain degree and considered useful, as they provide a wide range of ecological services. These services include protection from soil erosion, providing shelter and alternative food resource for beneficial organisms and pollinators.
Figure 1 shows the results of several studies comparing floral diversity on organic and on conventional fields. In all cases, organic agriculture showed higher floral diversity. Several comparative analyses carried out in Europe have shown plant species diversity in organic arable fields to be 30 to 350 percent higher than in conventional ones. In field edges, the number of plant species can be twice as high as in conventional fields, and the inner parts of the fields can have up to six times as many species compared to conventional fields.
In Sweden a number of declining, endangered and rare species were recorded on organic arable fields, showing that organic agriculture can contribute to maintaining biodiversity29.
In Romania, a weed survey in maize fields showed a significantly higher diversity of weed species in the organic maize field. This study had been carried out within the framework of a research project assessing the feasibility of organic agriculture in three Danube river countries. In this study positive effects of the organic system had also been recorded for further biodiversity indicators (e.g. ground-dwelling arthropods and earthworms)30.
In most cases, organic agriculture conserves better than conventional agriculture the site-typical plant community of floral species of arable land. A survey comparing organic with conventional fields showed that in the organic system the share of the fields with endangered floral species was 79 percent as opposed to 81 percent 27 years earlier, showing that the share had almost not changed. In the conventional fields the rate had dropped from 61 percent to 29 percent31.
The higher floral diversity and abundance in organic arable fields is generally due to the ban on synthetic N-fertilizers and herbicides. The limited availability and input of nitrogen, the application of mechanical and thermal weed control and more diverse crop rotations and a higher crop diversity lead to more favourable conditions for many wild plant species.
In organic grassland, the average number of species was found to be around 25 percent higher in organic than in conventional grassland, including some species in decline. The plant community structure in organic grassland is more even and more typical for a specific site than in conventional agriculture32. The higher floral diversity is often caused by lower stocking rates and lower fertilization levels in organic farms as well as to later mowing dates, especially in meadows, which means that grass species can reach the flowering stage and thus have a higher reproduction rate33.
The limited availability and input of nitrogen, the application of mechanical and thermal weed control and more diverse crop rotations and a higher crop diversity lead to more favourable conditions for many wild plant species.
Weeds influence the diversity and abundance of arthropods (e.g. beetles, ants and spiders), acting as natural food resource and shelter. Weeds like Umbelliferae, Leguminosae and Compositae play an especially important ecological role as they provide food and thus improve reproduction of many arthropod species34. Research carried out on tomato plots on the effects of weed control on surface-dwelling arthropod species found the abundance of species is clearly influenced by weed biomass. Species numbers were lowest where mulching with rye straw was controlling the weeds. However, removing weeds within 20 cm of each plant reduced weed biomass but retained higher arthropod populations than in the plots treated with herbicide or mulch35.
With regard to pollinators, which greatly benefit from a richness of flowers, the fact that flowering weeds are more diverse and more abundant in organic arable fields and in organic grassland compared to conventional fields, where only few species and numbers were found, is particularly important. Many insect species which feed on nectar and pollen have a higher reproduction rate when they benefit from a better food supply through species-rich plant communities.
It may be assumed that, as for butterflies36, the organic system also favours an abundance of further pollinators like bees and wasps. Flowering plants are also important for many beneficial arthropods such as predators and parasitoids37.
Orchards with rich floral undergrowth have a lower incidence of insect pests than orchards treated with herbicides, mainly because of an increased abundance and efficiency of predators and parasitoids.
Orchards with rich floral undergrowth have a lower incidence of insect pests than orchards treated with herbicides, mainly because of an increased abundance and efficiency of predators and parasitoids38. Similarly, in other permanent crops, cover crops do not only provide erosion control and nutrient supply but also a high floral and faunal species diversity. This is reported for organic olive production39 and for organic vine growing, for instance in California40.
In order to diversify the farming system and attract beneficial arthropods and pollinators, wild flower strips are sown in organic agriculture orchards. In a Swiss organic orchard, it was found that the strip management favoured beneficial insects and spiders, which reduced the density of aphids. The density of aphids was reduced due to higher mortality caused by increased numbers of predators feeding on aphids41. Measures aimed at managing appropriate habitats and thus increasing floral and structural diversity is a key strategy for improved natural pest control.
Organic agriculture displays in most cases a higher faunal biodiversity than conventional agriculture. Apart from the better food resources in organic fields, the key factors are more fauna-compatible plant protection management, organic fertilization, the more diversified crop rotation and the more structured landscapes with semi-natural habitats and field margins.
The effects of organic agriculture on faunal biodiversity have been studied particularly for soil fauna and for birds. A review of 44 research studies in Europe and the United States of America (on farm and pilot trials) on the effects of farming systems on beneficial invertebrates and birds consistently shows a better performance of the organic system (see Table 4). Of the faunal groups analysed (i.e. earthworms, arthropods and birds) in 49 out of 55 investigations organic agriculture performed better in terms of abundance. As regards species diversity, in 15 out of 23 investigations organic agriculture performed better; in no case conventional farming had a better performance.
Research studies in Europe and the United States of America (on farm and pilot trials) on the effects of farming systems on beneficial invertebrates and birds consistently shows a better performance of the organic system.
Most species of the mentioned animal groups in Table 4 are beneficial organisms and enforce ecological services.
The cases where biodiversity in organic systems is not better than conventional systems might be explained by the presence of robust species which do not have special requirements regarding their habitats, such as some spider species.
Earthworms are highly suitable bio-indicators of soil fertility, and they are known for their sensitivity to synthetic pesticides and to many agricultural practices. Due to their biology, earthworm populations can indicate the structural, microclimatic, nutritive and toxic situation in soils. In conventional agriculture, earthworms are affected by the use of harmful pesticides and intensive soil cultivation.
Earthworms generally increase nutrient cycling rates. Their casts greatly help to improve soil structure and have high concentration of nutrients in an accessible form to plants. The burrowing activity of earthworms enhances aeration, porosity and drainage of the soil, all of which are important factors in the development of healthy and well-developed crop root system. Earthworms also play an important role in pest and disease control, including the reduction of leaf miner pupae and scab pathogens in orchards42.
Many investigations in Europe and North America provide evidence that generally, organically managed soils exhibit a higher abundance and species number than conventionally-managed plots or farms43 (see Figure 2). The biomass of earthworms in the organic system in the Swiss DOC long-term trial was 30 to 40 percent higher than in the conventional system, the number of individuals even 50 to 80 percent higher44. Vertically-burrowing earthworm species which are of high agro-ecological relevance (e.g. for water infiltration, soil aeration, reduction of erosion) were enhanced by organic agriculture. Reasons for the higher presence of these species in the biological plots might be species-specific effects of pesticides45. Vertically burrowing species are more exposed to pesticides because they are crawling on the ground surface for feeding and mating. Furthermore they can be harmed by pesticide contaminated water flowing into their stable burrows. The decrease in juvenile earthworms in the conventional plots can be explained by the fact that upper soil layers are their preferred habitat. Thus, they may be exposed to higher pesticide concentrations than adults, because juveniles are unable to escape into deeper soil layers. In an organic barley field in Bulgaria in 1998, a single cubic meter of soil contained 124 earthworms compared to only 21 in conventional soil46.
Organic matter constitutes an important food source for earthworms and can be maintained by an appropriate fertilizing and crop rotation system. Investigations have shown that earthworms also benefit greatly from green manuring and the planting of grass-clover in the crop rotation47. The less intensive farming practices (plant protection, soil cultivation), the more favourable fertilizing management and the more diversified crop rotations on organic farms enhance specimen- and species-rich earthworm populations.
Beneficial arthropods that live above the ground include ground beetles (carabids), rove beetles (staphilinids) and spiders. Many of these polyphagous species, which feed on a wide range of food items, are important predators, and in arable crops they play an important role in the regulation of various pests48. In addition, certain arthropods, especially carabids, are considered as sensitive indicators of habitat quality49. Monitoring them yields useful information on the sustainability of different agricultural farming systems.
In conventional agriculture, synthetic pesticides can have negative impacts on beneficial arthropods. Pesticides affect arthropods either directly, via contamination or reduction of their prey, or through alterations of the micro-habitat. The reproduction rate may be reduced by sublethal long-term effects of synthetic pesticides used in conventional agriculture. Foliar fungicides can lead to mortality in springtails and thus negatively influence polyphagous predators50. Higher fertilization in conventional fields leads to higher crop density, and this in turn can alter the micro-climate as well as reducing the occurrence of species dependent on a warm micro-climate and on light. This phenomenon was found in the DOC long-term plot-trial as well as on farm level51. Organic fertilization can enhance epigeic arthropods through a richer supply of mesofauna decomposing organic compounds.
In several investigations of on-farm sites as well as in plot trials, a higher diversity and abundance of arthropods was found in organic and biodynamic plots compared to conventional plots (see Table 4). In the DOC long-term trial, the organic and biodynamic treatment had up to 100 percent more carabids, 60 to 70 percent more staphylinids and 70 to 120 percent more spiders (see Figure 3). The organic fields were also characterized by a generally more even distribution of species, which means that the community is less dominated by few species only52.
Table 4: Effects of organic and conventional agriculture on fauna
In several investigations of on-farm sites as well as in plot trials, a higher diversity and abundance of arthropods was found in organic and biodynamic plots compared to conventional plots.
Researchers have also found greater diversity and abundance of many other invertebrate species in organic agriculture systems (see Table 4). For example, a study comparing spider communities in organic and conventional winter wheat fields in the United Kingdom found the abundance and diversity of spiders greater on the organic fields. It was concluded that the results were highly affected by the increased levels of under storey vegetation (i.e. broad-leaved and grass species) in the organic fields53. Significantly more non-pest butterflies were recorded on organic farms than conventional farms but there was no significant difference in the abundance of pest species54.
The quality and amount of food are key factors for the survival of the arthropod populations, which find a higher proportion of suitable food resources in organic fields including flowering non-grass plants55.
Various typical agricultural practices (e.g. ban of synthetic pesticides, organic fertilization, and habitat diversity) on organic farms are less detrimental for arthropod species compared with conventional agriculture.
Birds are well-suited indicator organisms showing the environmental status of nature and landscape infrastructure including agricultural land. Many bird species feed on insects, and an abundant presence may thus also contribute to a better natural pest control.
The breeding populations of a number of bird species in Western European farmland have declined in the past decades. This development is probably linked to intensified agricultural practices, including a general reduction in crop diversity, an increase in average field size, simplified rotations, cultivation of natural habitats, drainage, and increasing use of fertilizers and synthetic pesticides. Investigations have found a relationship between pesticide use and a decrease in quality and amount of food available for birds on conventionally farmed land. A consequence is a decreased breeding success of birds56.
Several studies show that bird densities are higher in organic farms. A study by Rhône-Poulenc (1997) has shown a steady annual increase in the number of bird territories on land converted to organic production and a higher overall number of territories on the organically managed land.
A study by the British Trust for Ornithology (1995) compared breeding and over-wintering of birds on 44 organic and conventional farms. The study concluded that breeding densities of skylarks were significantly higher on organic farms and generally higher densities of birds, especially in winter, were found on the organic farms57.
A three-year study in Denmark concentrated on the non-crop habitats, such as hedgerows, of conventional and organic farms and their effects on bird populations. The abundance of birds was 2 - 2.7 times greater on the organic farms. In total, 24 species where more prevalent on organic as opposed to conventional farms, of these 11 species had declined in number in Denmark since 197658.
Christensen et al. (1996) investigated a total of 31 farms comparing the bird densities on organic land with those on conventionally managed land. On one of the sites investigated they found a mean population density of 22.8 pairs of breeding birds per ten hectares on the organic land compared to 9.9 pairs on the conventional land. Also flora and invertebrate fauna in organically versus conventionally managed land had been compared on the farms selected for the bird survey. By late June, the organic fields had 50 to 70 percent more species of wild plants than the conventional fields, with significantly more weeds and biomass. These differences increased markedly during the growth season due to herbicide treatment in the conventional areas. The average biomass in the organic fields was significantly more stable than in conventional fields, resulting in greater security of food supply. These results suggest that limited food availability is a key factor in the reduced number of birds in conventionally farmed areas.
In the coffee producing countries of Latin America, growing organic coffee and cocoa under shade can have a major impact on biodiversity. Research carried out by the Smithsonian Migratory Bird Centre in Colombia and Mexico showed over 90 percent fewer bird species in sun-grown coffee plantations as opposed to shade-grown coffee59. Although organic standards do not explicitly state the need for coffee to be grown in the shade, shade-grown practice is recommended as it fulfils require-ments to enhance soil fertility, pest and disease control and expands crop production option60.
In summary, reasons for the higher number and species diversity of birds and bird territories on organic farms include better breeding habitats and better food conditions. Further reasons for the higher bird species diversity and abundance are the absence of synthetic pesticides, more semi-natural habitats (hedges, field margins) and higher crop diversity on organic farms61.
Little work is available on the effects of organic agriculture on other wild animal groups. This could, however, be an important research theme, particularly with respect to pollinators. Many plants require pollen from other individuals to seed and regenerate.
Reasons for the higher number and species diversity of birds and bird territories on organic farms include better breeding habitats and better food conditions.
Over 80 percent of all flowering plant species and over three-quarters of the major world crops rely on animal pollinators. The principle pollinators are bees: approximately 73 percent of the world's cultivated crops, such as cashews, squash, mangoes, cocoa, cranberries and blueberries, are pollinated by some variety of bees, 19 percent of flies, 6.5 percent by bats, 5 percent by wasps, 5 percent by beetles, 4 percent by birds, and 4 percent by butterflies and moths62. Of the hundred principal crops that make up most of the world's food supply, only 15 percent are pollinated by domestic bees (mostly honey bees, bumble bees and alfalfa leafcutter bees), while at least 80 percent are pollinated by wild bees and other wildlife (as there are an estimated 25 000 bee species, the total number of pollinators probably exceeds 40 000 species). Services of native pollinators are estimated to be worth US$4.1 billion a year to United States agriculture alone63. Pollinators provide an essential ecosystem service that contributes to the maintenance of biodiversity, and ensures the survival of plant species including plants that provide food security to numerous households.
Declines in populations of pollinators now threaten both the yields of major food crops and the survival of wild plant species. Due to an epidemic of mites, a quarter of North America's wild and domestic honeybees have disappeared since 1988, with a cost to American farmers of US$5.7 billion per year64.
Currently, 82 species of mammalian pollinators, including bats, 103 species of avian pollinators and one reptile are considered threatened or extinct according to IUCN criteria, the ratio of threatened vertebrate pollinators to the total numbers of vertebrates in their genera being extremely high. Geographically, large numbers of vertebrate pollinators are at risk in Australia, Colombia, Ecuador, Indonesia, Madagascar, Mexico, Papua New Guinea, Peru, and the United States. Common threats include: loss of nesting and roosting sites, habitat fragmentation by conversion or destruction of vegetation, habitat fragmentation by excessive exposure of nectar plants to herbicides and pollinators to pesticides, over-hunting, disruption of nectar corridors required by migratory pollinators, and competition by invasive species65.
By not using synthetic chemical pesticides or herbicides and enhancing ecosystem diversity, it may be assumed that organic agriculture benefits pollinators and contributes to their conservation and survival.
According to the World Resources Institute, an ecosystem is made up of the organisms of a particular habitat, such as a farm or forest, together with the physical landscape in which they live. Although little research has been carried out comparing agro-ecosystem diversity in different farming regimes, many of the principles of organic agriculture are likely to have a positive impact on ecosystem diversity66.
The 2002 IFOAM Basic Standards for Organic Agriculture Production and Processing67 include principles and recommendations on "organic ecosystems" where provisions are made to "maintain a significant portion of farms to facilitate biodiversity and nature conservation", including (among others) wildlife refuge habitats and wildlife corridors that provide linkages and connectivity to native habitat.
The Swiss organic standards require organic farmers to use 7 percent of their land as semi-natural habitats, including field margins. Many other organic certification bodies have included biodiversity requirements in their standards. This applies to organic and low-input farmers receiving direct payments under the agri-environment schemes. Direct payments by the state are linked to ecological performance which is controlled by inspection services.
Organic agriculture has a high and possibly decisive potential for reversing the dramatic decline of biodiversity.
In Sweden, a working group made up of organic farmer groups, nature conservationists, Government agencies and universities has been working since 1997 to strengthen the links between organic agriculture and biodiversity conservation, and they set up biodiversity plans for organic farms. The main objectives, apart from helping organic agriculture enhance biodiversity, have been to start cooperation and dialogue between the nature conservation and organic agricultural movements and to spread knowledge about biodiversity in organic agriculture. From there, the discussions developed into a planning exercise leading to proposals for changes to the country's main organic standard (set by the certification body, KRAV), to require all organic farmers to have a plan for the management of biodiversity on their farms from 200168.
Organic agriculture has a high and possibly decisive potential for reversing the dramatic decline of biodiversity. However, further efforts must be taken to refine the basic organic standards for biodiversity and landscape. Actual experiences show that there is a considerable and diverse synergy potential between biodiversity conservation and farm income. Biodiversity issues based on measurable performance are more and more important as a basis for subsidies and, at least in some countries, for consumer decisions for buying organic products.
The conservation and the management of semi-natural habitats play an important role in organic agriculture. Semi-natural habitats are refuges for endangered plant species which in former times were found in meadows and arable fields. Semi-natural habitats and field margins are also essential for the survival of many invertebrates, especially due to favourable food and over wintering conditions. They also function as habitat cross-links between meadows, fallows and different field margins.
Quantitative data from Switzerland69 found that the proportion of semi-natural habitats and field margins per farm to be 16 percent on organic farms, compared to 3.7 percent on conventional farms. It was also noted70 that in Germany organic farmers took specific measures to increase the habitat diversity (hedges, low-input orchards, ponds, corridors, habitat networks, wildlife refuges and devices) as well as to better connect farmed areas and the surrounding habitats.
A recent study71, also in Switzerland, shows how important the combination and integration of semi-natural habitats with organic farms is for the conservation and enhancement of species diversity and abundance of beneficial arthropods. In this study organic agriculture had been compared with low-input integrated crop management within the framework of a paired farm survey. Also nearby semi-natural landscapes have been used to compare the effects of organic agriculture and low-input farming system on carabid beetle and spider fauna. Many endangered or rare species which are enhanced by semi-natural habitats and field margins were more abundant in organic arable fields than in the integrated managed fields. Also, agro-ecologically important carabid species and wolfspiders were found in higher numbers on the organic farms. This aspect indicates that the improvement of landscape infrastructure in combination with organic agriculture may be an important factor for the conservation and enhancement of species-rich communities on agricultural land. Furthermore, this approach has demonstrated a better natural pest control for a rape pest (the rape pollen beetle) in Germany72 and for the cherry oak aphid in Sweden73.
Organic agriculture has the potential for a positive landscape development because it itself need a rich and diverse landscape infrastructure with semi-natural habitats74. By studying the whole farm, or even the whole landscape within which the farm operates, researchers are trying to find ways to characterize the benefits of organic agriculture to the ecosystem. A research project funded by the European Union found that the diversity of landscape and farming systems was greater in organic farms, regarding land use types, crops, livestock, plantings (hedges, solitary shrubs, trees) and flora. In terms of landscape diversity, the organic types of agriculture have a good potential for positive contributions to a sustainable agrarian landscape75.
Protected areas, as defined by the World Commission on Protected Areas, are areas especially dedicated to the protection and maintenance of biological diversity. Protected areas are not always strict nature reserves. Instead, they can fulfil many functions alongside biodiversity conservation. Because of its biodiversity benefits, organic agriculture offers an important agricultural management option in several protected area categories76.
Because of its biodiversity benefits, organic agriculture offers an important agricultural management option in several protected area categories.
In Italy for instance, the Italian Association for Organic Agriculture (AIAB) project on "Organic Agriculture and Agro-ecology in Regional Parks" has been working with the regional park authorities in the Emilia-Romagna region to promote organic agriculture in relation to the regional agri-environment programme. During the first two years of activity (1996-1997) there was an increase in the rate of adoption of the regional agri-environment programme, particularly of organic agriculture, by farmers in the park and the buffer zone. Between 1996 and 1997, 113 farms in the area applied for organic certification, compared with only 73 between 1994 and 199677.
There are further examples from Europe and the United States where organic agriculture is promoted in the biosphere reserves. The Estancia Itabo in Paraguay embodies a protected area of 5 000 hectares of high quality Interior Atlantic Forest. The Estancia is a good example of sustainable rainforest use in line with the conservation goals of the protected area by cultivating organic yerba mate and the heart of palm Euterpe edulis78.
A secondary and closely connected link between ecosystem diversity, protected area management and organic agriculture is in the buffer zones (the region near the border of a protected area). Buffer zones are by their nature areas where land management aims to help maintain the integrity of the ecosystem of the core protected area. Where agriculture is the dominant land-use in buffer zones, the detrimental effects of farming systems can be reduced by conversion to organic systems.
The use of organic agriculture in protected buffer zones has been explored in the Meso-American Biological Corridor, a complex of protected areas and sustainable management stretching over seven countries. The initiative envisages a range of sustainable land uses within the buffer zones and linking areas, including certified forest management and organic agriculture79.
In Peru, organic agriculture practices are promoted in the buffer zone of the Ampay Forest Sanctuary. Thanks to information measures, the awareness of the population about the biological importance of the sanctuary was increased, and as a result the area has converted into a high-priority conservation area for ecotourism, governmental and private investment in infrastructure, promotion and conservation of natural resources80.
Where agriculture is the dominant land-use in buffer zones, the detrimental effects of farming systems can be reduced by conversion to organic systems.
There is increasing recognition among nature conservation organizations that many species interact with agricultural systems, even if their primary habitat is in natural areas. The management of these agricultural systems can, thus, dramatically affect overall levels of biodiversity, as well as the success of particular species. The German conservation organization BUND claims that traditional concepts of nature protection have failed because conservation goals have not been achieved, even in protected areas, due to agricultural intensification in the surrounding areas. Many conservation organizations are therefore calling for a general extensification of agricultural land use and promote organic agriculture for that reason81.
In 1999, a joint workshop in Vignola, Italy, organized by The World Conservation Union (IUCN) and IFOAM together with the World Wide Fund for Nature (WWF), was held to exchange ideas and information on organic agriculture and biodiversity. A joint action plan for both the nature conservation and organic movements was drawn up in the so-called Vignola Declaration82.
In both developed and developing countries, one of the driving forces behind the growth of organic agriculture is the nature conservation agenda. Though less significant than market prospects and development prospects, a recent literature survey highlights a number of examples where nature conservation organizations are working closely with local farmers who live in, or close to, areas of significant nature conservation interest83.
In the last twenty years, governments also have been gradually moving towards policies aiming at encouraging the links between organic agriculture and biodiversity conservation.
In the European Union, environmental concerns have gained a more prominent place in agricultural policy. The most notable contribution of the Common Agricultural Policy of the European Union towards more environmentally sustainable systems has been the introduction of the agri-environment programmes in 1993, which now continue under Agenda 2000. The impetus for some of these initiatives comes from the Convention on Biological Diversity.
The implementation of agri-environmental measures over the whole of the European Union and also other European countries is the core of the European Community's environmental strategy. So far, organic agriculture has played a central role in most countries' national agri-environment policy. The main reason for this policy support has been the perceived positive environmental effects of organic agriculture84.
Also in other parts of the world, governments and development agencies are beginning to promote organic agriculture, especially in protected areas, because of its biodiversity benefits.
Organic agriculture brings several environmental benefits but the question arises on the threshold for converting land to organic management. One approach to determining this is to examine the benefits obtained from moving away from conventional agriculture. One estimate of the negative environmental externalities from conventional agriculture in the United States is derived from Pimentel et al. (1993) who estimated total indirect private and external (off-farm) costs of the use of synthetic pesticides at US$12.1 billion annually: this included the private input costs of US$4 billion and US$5 billion in environmental and health costs. Farmers had a US$12 billion incentive to use these pesticides. By comparison, the private benefits captured by the farmers were calculated at US$16 billion but in their decision they were ignoring the costs of US$8.1 billion imposed on the rest of society. These rather dated estimates indicate the nature and magnitude of the problem.
Redman (1996) estimated the costs of cleaning drinking water in the United Kingdom in excess of US$2 billion in initial investments plus US$240 million annually. These costs relate to pesticides and nitrate pollution.
So far, organic agriculture has played a central role in most countries' national agri-environment policy.
Examples of environmental externalities should be used with caution because of the difficulties of assessing environmental damage and valuing the benefits of avoiding it. By their nature, there are no markets to value environmental externalities. One preventive approach to this problem is to set environmental standards and design measures that can best achieve these standards.
Another approach to estimating costs is to look at the costs of compliance to environmental regulations. A study comparing the impacts of environmental standards on agriculture in Australia, Canada, the European Union, New Zealand and the United States concludes that the compliance costs would normally be less than 3 or 4 percent of gross revenue, although intensive livestock industries face the greatest external costs85.
Agricultural-related environmental problems relate chiefly to water quality and intensive livestock operations. To illustrate this point, research using the United Kingdom Government data suggests that the costs of meeting the Nitrates Directive in England and Wales reduced net farm income by 2.4 percent in the poultry sector, 11.3 percent in the pig industry, 4.5 for beef and 9.6 on dairy farms86. Most of the cost relates to capital expenditure to adequately handle manure. Animal welfare regulations for poultry and pigs are estimated to reduce net farm income by 38 and 6 percent respectively. Crops do not face the same compliance costs. The implications of these estimates are that perhaps environmental concerns do not justify the abandonment of pesticides and synthetic fertilizers that a widespread shift to organic agriculture would entail. However, this approach ignores the environmental damage that occurs even though the regulations are being met.
There is some evidence that consumers who have recently entered the organic market are less motivated by ecological issues and are more interested by organic food as a safe product87. What is interesting is that sales of organic products have increased markedly as a result of recent food scares88, suggesting that new consumers are concerned about the product itself as well as, or perhaps rather than, the environment in which it is produced. However, the increases in sales have not related to the particular products (that is, beef) to which the scares applied. This distinction between food safety and environmental concerns has important implications for future production and policies.
1 Fliessbach et al., 2001.
2 Lampkin, 1990; Stolton et al., 2000; IFOAM, 2000.
3Diez et al., 1985; Niederbudde and Flessa, 1988; Beck, 1991.
4 See also section 3.3.
5 Smith and Read, 1997; Mäder et al., 2000.
6 The DOC trial was started in 1978 in Switzerland. In this long-term (more than 20 years) trial the three farming systems are compared in a randomised plot trial: bio-dynamic, bio-organic and conventional (Fliessbach et al., 2001).
7 Pfiffner, 1997; Pfiffner and Mäder, 1997.
8 Stolze et al., 2000.
9 Kilcher, 2001.
10 Haas & Köpke, 1994a; Lampkin, 1997.
11 Zarea et al., 2000 (in Iran); Fliessbach et al., 2001 (in and).
12 Ciani and Boggia, 1993; Ciani, 1995.
13 Haas and Köpke, 1994.
14 Schulze Pals, 1994.
15 Offermann and Nieberg, 1999.
16 IUCN, 2000.
17 Convention on Biological Diversity, 2002.
18 Letourneau and Goldstein, 2001.
19 European Environment Agency, 2002.
20 Southwood and Way, 1970.
21 Shiva, 2001.
22 FAO, 1998.
23 FAO, 2000b.
24 IFOAM, 2000.
25 Wairegi, 2000.
26 Crabb, 1997
27 Spears, 2001.
28 Quist and Chapela, 2001.
29 Rydberg and Milberg, 2000.
30 Znaor and Kieft, 2000.
31 Frieben, 1997.
32 Frieben, 1997.
33 Frieben and Köpke, 1996.
34 Altieri, 1999a.
35 Yardim and Edwards, 2000.
36 Feber et al., 1997.
37 Hald, 1999.
38 Altieri, 1999a.
39 Kabourakis, 1996.
40 Bugg and Hoenisch, 2000.
41 Wyss, 1994; Wyss et al., 1995.
42 Kennel, 1990.
43 Review in Pfiffner, 1997.
44 Pfiffner and Mäder, 1997.
45 Lofs-Holmin, 1980; Kula and Kokta, 1992.
46 Znaor and Kieft, 2000.
47 Pfiffner, paper under preparation.
48 Luff, 1983; Nyffeler and Benz, 1987.
49 Steinborn and Heydemann, 1990.
50 Burn, 1989.
51 Pfiffner and Niggli, 1996; Pfiffner and Luka, 2000.
52 Pfiffner and Niggli, 1996.
53 Feber et al., 1998, reported in Soil Association, 2000.
54 Feber et al., 1997.
55 Hald, 1999.
56 Christensen et al., 1996.
57 British Trust for Ornithology, 1995.
58 Brae et al., 1998, reported in Soil Association, 2000.
59 Alger, 1998.
60 Rice and Ward, 1996.
61 Rösler, 1997.
62 University of Albany, 2002
63 Prescott-Allen, R. and Prescott-Allen, C., 1990.
64 McNeely and Scherr, 2001a.
65 Nabhan, 1998.
66 Stolze et al., 2000.
67 IFOAM, 2002.
68 Mattsson and Kvarnbäch, 2000.
69 Hausheer et al., 1998.
70 Frieben, 1997.
71 Pfiffner and Luka, 2002.
72 Thies and Tscharntke, 1999.
73 Östmann et al., 2001.
74 van Elsen, 2000.
75 Mansvelt and van der Lubbe, 1999.
76 Stolton and Dudley, 2000b.
77 Compagnoni, 2000.
78 Pryor, 2000.
79 Stolton and Dudley, 2000a ; Miller et al., 2001.
80 Flores-Escuerdo, 2000.
81 Weiger, 1997.
82 Stolton et al., 2000.
83 Parrot and Marsden, 2002.
84 Stolze et al., 2000.
85 Brower and Ervin, 2002.
86 Wilkensen, cited in Brower et al., 2002.
87 Sylvander and Leusie, 2000.
88 Haring et al., 2001.
