Mixed farming systems & the environment

Previous section Mixed farming systems in the developing world: Nutrient deficits

Mixed farming systems in the developed world: Nutrient surpluses

The mixed farming systems of the developed world cover about 17 percent of the world's pasture land and half of its arable land. They contain about one-fifth of both the world's cattle and small ruminant population. These systems generally show a much slower growth than mixed farming systems in the developing world. In some countries, mixed farming is contracting, reflecting the combination of stabilized demand in the OECD countries and the decline in the former Soviet Union and Eastern Europe, because of restructuring following the transition to a market economy.

Environmental challenges

With increasing population pressure, growing incomes and improved infrastructure and market opportunities, more intensive forms of crop and livestock production, including integrated systems evolve. These integrated systems come into dis-equilibrium in several regions of the world as a consequence of large nutrient imports from outside the region, causing an overloading of soil and water with pollutants. The environmental challenge in the industrial countries, and to a large extent also in the fast growing economies of east Asia, is thus to identify, before it is too late, the point where land and aquatic eco-systems become overloaded. This is better than trying to identify technologies and policies which mitigate the negative effects of nutrient overloads once they have occured. In other words, “prevention is better than cure”.

A further environmental challenge is to maintain biodiversity and an aesthetic landscape in heavily populated and developed mixed farming areas. Although opportunities to conserve biodiversity will not be able to mimic exactly the diversity associated with mixed farming in less developed areas, it should be possible to achieve some level of conservation. The challenge is to put in place technologies and policies which encourage farmers to retain a mixed farming system instead of specializing in the production of one or two crops only.

State

In the developed world, the environmental effects of mixed farming systems may include a deterioration in land and water quality (through soil erosion and nutrient loading), and biodiversity loss, especially through habitat change.

Soil erosion in the temperate zones (for example in the United States and in Europe), with a loss rate of about 15 ton/ha/yr, is half that of the developing world. But even this lower erosion rate exceeds by far the average soil formation of about 1 ton/ha/yr. (Pimentel et al., 1995).

Soil fertility. Soils in north western Europe, (the Netherlands, Germany, Britanny in France) in the eastern and midwestern USA and in the fertile and densely populated, and increasingly affluent, areas of east and south Asia, often reveal a surplus of nutrients. There are also widespread areas of central and eastern Europe where, as a result of very large livestock production units, there is a serious surplus of soil nutrients. While the total area with surplus nutrients is probably still very small (less than one percent of global arable lands (Rabbinge, pers. com.), through runoff its effect on water quality is much more widespread. Often such areas are near ports and/or large urban areas so that the transport costs associated with imported fertilizers, and the subsequent sale of milk and meat, are low.

The excess nitrogen and phosphorus “leaks” through leaching or run-off in surface or groundwater, damage aquatic and land eco systems. In Pennsylvania about 40 percent of the soil samples taken from dairy-crop farms revealed excessive phosphorus and potassium levels. Soils are saturated and surplus nutrients leach into surface water, pollute the environment, in this case the Chesapeake Bay. A similar situation is found in Brittany, France where all eight counties report nitrate levels of more than 40 mg/litre whereas, in the 1980s, only one county reported levels this high (Jansen and de Wit, 1996).

Biodiversity. The intensification of mixed farming and the subsequent shift in production towards regional specialization puts pressure on plant and animal biodiversity. In addition, the move towards sown pastures coupled with high levels of organic and inorganic fertilizer use reduces the richness of flora and fauna. This problem can be exacerbated by the use of insecticides for the control of external parasites, especially in areas with high water tables.

Driving forces

Soil erosion is strongly influenced by grazing pressure and cropping intensity. Reynolds et al., (1995) reported how variable soil erosion can be observed under different grazing pressures. Soil loss on lands with a good grass ground over has been estimated at 1 ton per hectrare, this increased dramatically on overgrazed pastures to a level of 53 tons per hectare. If grazing pressure is in balance with the forage resource being produced, livestock's interaction can encourage more stable land use practices. Pimental et al., (1995) discussed how, in the United States, in order to increase farm size, grass strips and shelter belts were removed, thus increasing the erosion rate. In the past, livestock provided a rationale for grass strips and shelter belts but, with the separation of crop and livestock systems in OECD countries, the rationale for using land resources in this way has weakened.

Nutrient surpluses are the main cause of deteriorating land and water quality. These surpluses come from a combination of inorganic and organic fertilizers. Inorganic fertilizer is used, in spite of the fact that the system could be balanced using the nutrients supplied by the manure produced within the farming system. For example, in Brittany, organic manure produced by intensive industrial and mixed farms of the region could provide adequate nutrients but substantial surpluses emerge because of the additional import of large quantities (between 35 and 100 kg N/ha per year) of inorganic fertilizers. Inorganic fertilizer is said to be necessary because of the ready availability of its nutrients and its easy transport but, as in pure intensive grazing systems (Box 2.13), lower inputs might be adequate and even more economical. The preparation of nutrient balances (inorganic and organic) on a regional basis is therefore a critical element in identifying land conservation and fertilizer policies.

Policies designed to protect domestic production of most animal products, especially beef and milk, against imports and a broad array of producer subsidies, especially on feed imports, have led to the wide use of feed concentrates and therefore to situations where nutrients are in surplus. Such situations occur most often on the many smallscale enterprises which tax advantages and quota systems usually favour and where regulations are more difficult to enforce. Smaller size enterprises tend to have more lenient standards and are able more easily to exploit loopholes in regulations designed to protect the environment. These intensive systems using concentrate feed demonstrate how policies designed for social objectives can misdirect resource use and technology development.

Response: Technology and policy options

Policy. In the developed world, regulations are being introduced to restrict the emission of nutrients in the case of point source pollution, and restrict stocking rate (“manure quota”) in the case of non-point source polluters. A cross section of current legislation in some of the developed and developing world is provided in Table 3.3. Regulations include a variety of restrictions on stocking rate and use of fertilizer, manure storage and times and techniques of application, encouraged by government subsidies on manure processing and management.

• A variety of measures may be introduced to reduce nutrient surpluses. These include:
• taxation of inorganic fertilizer, in order to discourage unnecessary use where a system is already in surplus;
• maximum application limits and regulation of times of application in order to reduce leaching and volatilization (Box 3.3);
• taxation on feed imports to reduce the significant transfer of nutrients from the already nutrient deficient developing world to the nutrient surplus areas of the industrialized world. Such taxation might be supplemented with, or used as, subsidies for a transfer of nutrients back to the developing world;
• incentives to achieve a more balanced distribution of crop and livestock activities.

Technology. Of particular importance are the following technologies to reduce nutrient surpluses:

• Improved nutrient formulation in terms of incorporating optimum levels of nitrogen into feed and adding enzymes to improve the utilization rate of plant phosphorus. Optimum nutrient ratio and composition management reduce loading the environment with these elements; and
• Improved manure handling and storage are key requirements (Chapter 4) for more efficient use in nutrient deficient areas, and to prevent leaching and pollution of surface water where there is a nutrient surplus. Box 3.8 gives an overview of some of the most common factors which determinine whether the effect of manure is minimal, moderate or severe.

In addition, over the last decade, there has been considerable interest in promoting low-input mixed farming systems, as sustainable and environmentally friendly systems. In the USA, the Rodale Institute in Pennsylvania, and the LISA (Low Input Sustainable Agriculture) movement, strongly promoted by USDA have been in the forefront. In Europe, the ILEIA (Institute for Low External Input Agriculture) has been one of the prime movers. Mixed farming systems are often especially suitable for low-input production. Some of the main technologies which can be used in the livestock sector are:

• use of grass-legume mixtures as the basic feeding system for ruminants. The nitrogen fixation of legumes (such as clovers), can replace the nitrogen lost through milk and meat;
• mixed species grazing (cattle and small ruminants), which increases grass yield, botanic composition and reduces the parasite load;
• genetic improvement focusing on maximum capacity to digest roughage, rather than on concentrate feed consumption, and based on life-time production, rather than on short term lactation yield, to achieve optimum efficiency on the basis of renewable resources;
• housing, which allows adequate movement and is based in the animal's natural social behaviour, produces high quality manure using large quantities of straw;
• disease control based on good feeding and breeding practices, and preferably using organic medicines, to mimimize environmental contamination.

On the crop side, this has to be accompanied by environmentally friendly low-input techniques, such as zero tillage, manuring and composting, integrated pest management (IPM) etc. Precise information about soil nutrient levels, coupled with economic incentives, not only helps to minimize production costs but also helps to maintain the soil nutrient balance as well as a landscape that is aesthetically pleasing.

The National Research Council of the United States (1989) has provided some excellent guidelines for low-input agriculture.

Low-input farming can have a special attraction to consumers who like to buy “environmentally safe” products under “green” labels and to support eco-farming, organic farming, etc. As for any other food product “green label”, food must be subject to clear and strict quality standards (especially regarding residues) and be supervised by reliable quality control systems. Prices of such “organic” food products are between 20 and 50 percent higher than conventionally produced foods, mainly as a result of low volumes and stagnant market share (2 to 5 per cent of the EU market). Producers, who are therefore unable to practise economies of scale, nevertheless have to meet high distribution costs.

“Green label” eggs (free range production) are one of the most widespread products and now have a market share of 5 to 10 percent in the EU. By and large, low-input production has, until now, only proved viable where consumers are ready to pay a premium for “eco-products” and where there is market saturation.

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