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Unit 7: Agriculture // Section 9: Sustainable Agriculture

Growing concern about agricultural intensification in developed countries and its negative environmental impacts spurred an alternative movement in the 1970s to promote what advocates called sustainable agriculture. This perspective drew inspiration from sources that included organic farming (raising crops and animals with minimal synthetic inputs), the international environmental movement, and development advocates who criticized the Green Revolution for relying too heavily on pesticides and fertilizer. Ecology is a central pillar of sustainable agriculture, which treats farmed areas first and foremost as ecosystems, albeit unique ecosystems that have been disturbed and simplified by harvesting.

Few people would argue against the concept of sustainable agriculture, but there is no universally-agreed definition of what it means. Agricultural economist Gordon Conway describes sustainability as "the ability of an agroecosystem [an agricultural ecosystem and its social and economic setting] to maintain productivity in the face of stress or shock." Farmers use countermeasures to respond to stresses and shocks. They may draw on resources that are internal to the system, such as plants' natural pest resistance, or on outside inputs like herbicides and fertilizers.

Internal inputs typically rely on natural resources. Figure 15 shows the re-emerging practice of green manuring—tilling fresh plant material into soil to improve its physical and biological qualities. Outside inputs may be equally useful, but they usually cost more and may alter farming systems in unexpected ways—for example, introducing new species that compete with established crops (footnote 16).

Chopping and disking mustard green manure, Washington state, 2003

Figure 15. Chopping and disking mustard green manure, Washington state, 2003
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Source: Washington State University Extension.

Other formulations of sustainable agriculture, including legislation passed by the U.S. Congress in 1990, present it as a compromise between several sets of social goals, including but not limited to environmental conservation. Producing enough food, fuel, and fiber to meet human needs is a major objective, along with improving environmental quality, using non-renewable resources efficiently, and ensuring that farmers can earn reasonable livings from their products (footnote 17). In terms of methods, sustainable agriculture typically stresses treating soil as an ecosystem and using methods to keep it healthy, such as retaining organic matter and preserving diverse communities of soil organisms.

Many people equate sustainable agriculture with organic farming, which is practiced according to national legal standards in more than 60 countries, including the United States, the European Union, Britain, Canada, and Australia. Generally, organic standards bar the use of synthetic pesticides, herbicides, fertilizers, and genetically modified organisms for crop production and use of antibiotics, hormones, and synthetic feeds for animals. Organic agriculture typically has less severe environmental impacts than intensive farming with synthetic inputs. On average, organic farming conserves biodiversity, improves the structure and organic content of soil, leaches less nitrate into water bodies, and produces much less pesticide pollution.

As of 2002–2003, about 4 percent of utilized agricultural land in the European Union and up to 4 percent of farmed land for certain crops in the United States was farmed organically (Fig. 16). Together, the United States and the E.U. account for 95 percent of global organic food sales.

U.S. certified organic acreage and operations, 2003

Figure 16. U.S. certified organic acreage and operations, 2003
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Source: United States Department of Agriculture, Economic Research Service.

Organic farming is not without its drawbacks. Output from organic farms is typically lower than from conventional agriculture for at least several years after shifting to organic production, because it takes time to restore soil productivity naturally and establish beneficial insect populations. Organic agriculture is more labor-intensive than conventional farming, so production costs are higher and farmers must receive higher prices to make a profit. And transitioning to organic production takes several years, so it is too expensive and difficult for small-scale farmers without access to technical assistance and transition funding.

With world population projected to rise from 6.5 billion in 2006 to roughly 10 billion by 2050, and growing demand for meat in developing countries (which increases demand for grain as livestock feed), world grain production may have to double in coming decades. If nations take the intensive route to this goal, using even more fertilizer, pesticides, and irrigation, nutrient pollution and freshwater depletion will increase well beyond current levels—the antithesis of sustainable agriculture (footnote 18).

One potential solution currently at the experimental stage is "precision agriculture"—using remote sensing to help farmers target fertilizer, herbicides, seeds, and water to exact locations on a field, so that resources are not over-applied or used where they are not needed. For example, satellite data could identify sectors within large cultivated fields that needed additional water or fertilizer and communicate the information to farmers driving machinery equipped with global positioning system receivers (reducing the need to apply inputs uniformly across entire fields) (footnote 19).

More broadly, agriculture will have to become more efficient in order to double world grain production without further degrading the environment. No single innovation will provide a complete solution. Rather, feeding the world sustainably is likely to require a combination of many technological inputs and sustainable techniques.

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