"The plowshare may well have destroyed more options for future generations than the sword," writes Wes Jackson in a review of practices that have brought U.S. agriculture to the edge of disaster. Tillage has hastened the erosion of irreplaceable topsoil everywhere and a technology based on fossil fuels has increased yields for short-term profits, leaving crops ever more vulnerable to diseases, pests, and droughts. Such, says Jackson, is "the failure of success." As high-technology agriculture becomes more wasteful and expensive, more farmers are being forced off the land or into...