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The Sustainable Approach to Agriculture Sustainable agriculture can provide high yields without destroying the environment or undermining current productivity. Farmers who take a sustainable approach substitute knowledge for pesticides and fertilizers. They use crop rotations and other adjustments of the agricultural system to solve problems. For example, soil enrichment produces healthy plants that resist disease, cover crops retard erosion and control weeds, and natural predators help control pests. The result is that farmers are able to minimize their use of pesticides and fertilizers, thereby saving money and protecting the environment. Crop rotation--growing different crops in succession in the same field--is one the most powerful techniques of sustainable agriculture. It can play a major role in pest control because many pests have preferences for specific crops. Continuous culture--growing the same crop year after year--guarantees pests a food supply and so pest populations increase. Growing different crops interrupts pest life cycles and keeps their populations in check. For example, right now European corn borers are often a significant pest because most corn in the United States is grown in continuous cultivation or in two-year rotations with soybeans. If corn were part of four- or five-year rotations, corn borers would not be major pests. Such rotations would control not only corn borers, but many other corn pests as well. In fact, rotation reduces pest pressure on all the crops in the rotation by breaking the pest reproductive cycles. Rotation is a key element of the permanent and effective solution to pest problems. In rotations, farmers can also plant crops, like legumes, that replenish plant nutrients, thereby reducing the need for chemical fertilizers. A good example is soybeans, a valuable crop that also converts nitrogen into a biologically useful form. Corn grown in a field previously used to grow soybeans needs less added nitrogen to produce high yields. An alternative to leaving the ground bare between cropping periods is the planting of cover crops, like hairy vetch, clover, or oats. Although such crops are usually not harvested for sale, they provide multiple benefits by preventing soil erosion, suppressing weeds, and enhancing soil quality. Thus using appropriate cover crops can reduce the need for chemical inputs like herbicides, insecticides, and fertilizers. Soil is arguably the single most prized element of agricultural ecosystems. Unless it is sterilized by the overuse of pesticides, soil teems with life. Good soils can improve yields and produce robust crops less vulnerable to pests; abused soils often require heavy fertilizer application to produce high yields. Soil quality can be maintained and enhanced in many ways, including incorporation of animal waste (manure), living plants, or plant debris (compost.) One of the most promising new technologies is the control of pests through integrated pest management. IPM begins with accurate diagnosis of pest problems, then chooses responses from a range of actions including use of sterile males, biocontrol agents like ladybugs, and, as a last resort, reduced-risk chemical pesticides. Biointensive IPM, which relies to the greatest possible extent on biological rather than chemical measures, emphasizes the prevention of pest problems with crop rotation, microbial control of root pathogens, and release of beneficial organisms that prey on the pests. The following sites provide more information on the methods used for sustainable agriculture:
Union of Concerned Scientists 2 Brattle Square, Cambridge, MA 02238-9105 Phone: 617-547-5552 Email: ucs@ucsusa.org http://www.ucsusa.org/agriculture/sus.ag.methods.html (Web site for the original of this page) |