Better Rotations Cut Pollution, Not Profits

Better Rotations Cut Pollution, Not Profits

Clover frost-seeded in winter wheat improves soil and helps supply nitrogen for the next cash crop. Photo by T.L. Gettins/Rodale Images

More diversified crop rotations can provide environmental benefits at virtually no overall cost to farmers, a SARE-funded project in Michigan shows. Researchers compared corn-corn-soybeans-winter wheat/frost-seeded red clover rotations on 10 farms of varying size with continuous corn on five farms with similar soil types. Rotation increased farmers' corn yields an average of 19 bushels per acre. By growing red clover before corn, many of the farmers reduced their corn's nitrogen sidedress rate by at least 60 pounds per acre. Net returns in the multicrop rotations averaged $103 per acre, versus $84 for continuous corn. This was a relatively small sample of farms, however, and economic results will vary with commodity prices and farm-management practices, the researchers note. But computerized modeling based on the on-farm results clearly showed environmental benefits are affordable: Phosphorus runoff from cornfields can be held below 8 pounds per acre and nitrate leaching below 40 pounds per acre at negligible cost when farmers improve their rotation. Increases in soil carbon, water infiltration and nitrogen mineralization were seen on some farms, suggesting that a diversified rotation also improves soil health. Well-attended field days, several Extension training sessions and numerous research reports have emphasized the benefits of integrated crop management and the value of including legumes in crop rotations. (North Central Region project LNC93-57.)

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