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Besides using new planting methods, farmers are experimenting with novel ways of fighting pests without resorting to chemical weapons. Joe and Dalton Maddox, a father-son team in Colorado City, Texas, once tried to eliminate mesquite on their 22,000-acre sheep-and-cattle ranch by dousing it with herbicides. Now they let the mesquite grow, relying on a cover of luxuriant pasture to control its spreading. "We used to spray for cockleburs, which were a big problem for our sheep," says Joe Maddox. "They would get into the wool and damage it. Then we got to thinking of what the herbicide might be doing to Lake Spence, which is a source of drinking water for a number of people." Instead of spraying, the Maddoxes now bait cocklebur stands with salt to attract cattle. The cattle mill around the salt, crushing the pesky cockleburs underfoot.
One of the most effective ways to reduce chemical use is also one of the simplest: crop rotation. Dick and Sharon Thompson of Boone, Iowa, do not merely rotate corn and soybeans, as many of their neighbors do. They also include in their scheme legumes such as alfalfa and red clover, taking advantage of those plants' nitrogen-fixing ability to reduce the need for fertilizer when they plant corn. To control weeds, the Thompsons rely on mechanical cultivation, restricting their use of herbicides to hand-spraying the recalcitrant thistles that grow along fencerows. Hogs and cattle round out the operation, a reliable source of manure that takes the place of chemical fertilizer.
Abutting the Thompson place is land farmed by neighbor Dave Snyder. Like many larger growers, Snyder has judiciously reduced his use of chemicals over the years. But he finds the idea of replacing herbicides with mechanical cultivation on 1,800 acres wildly impractical. Last fall the U.S. Department of Agriculture began a multiyear study of two fields farmed by Snyder and Dick Thompson. Snyder's field produced eight more bushels of corn an acre. But Thompson's field was riddled with soil-enriching earthworms, while Snyder's boasted none.
Despite its benefits, sustainable agriculture is not a panacea. Attempts to prevent soil erosion, for example, could enhance the ease with which water seeps into the soil, and might actually speed the passage of chemicals into underlying aquifers. Manure is organic, but if carelessly applied, it can pollute drinking water with nitrates as easily as artificial fertilizers do.
Ultimately, the spread of sustainable agriculture will be determined by economics. High prices for pesticide-free produce have encouraged large California growers like Mike Yurosek & Son, which last year committed 1,100 acres to organic carrots. "Farmers have to be convinced that these techniques are profitable," underscores Paul Thompson, an agricultural ethicist at Texas A&M University, "and that they will not involve a personal sacrifice." Farmers remain wary of efforts by environmental groups to legislate reductions in chemical use. In California, for instance, an initiative nicknamed the Big Green is poised to appear on the ballot come November. Among other things, it threatens to phase out up to 15% of the pesticides currently used in the state. California's influential farm lobby is preparing a massive counterattack.