50 to 90 percent, and is already used on about 25 percent of U.S. farmland. Higher costs, farmers' habits, and subsidies for certain crops are among the factors slowing wider implementation of such techniques.
A greater imponderable is the possibility of a sudden climate change. Nevertheless, the authors argue, Washington policy-makers should do more to limit such long-term risks. Among their options: encouraging wider dispersal of farms and diversification of crops in one-crop re- gions, ending...