Agricultural output all over the world is being reduced due to soil erosion and an increase use of cropland for nonfarming purposed. A. Terracing, probably one of the oldest methods for controlling soil erosion, led to the creation of the more sophisticated and more efficient conservation practices used in contemporary farming. B. After the 1930s Dust Bowl, the United States made significant changes to its agricultural practices, including the planting of tree shelterbelts and strip cropping. C. The United States has successfully instituted programs that encourage conservation tillage and the retirement of highly erodible land. D. The Conservation Reserve Program created in the United States in 1985 is gradually being adopted in other areas of the world such as Europe, Africa, and Asia. E. City governments in the United States and Japan developed conservation programs that encourage farmers near big cities to cultivate crops that minimize soil erosion. F. Saving cropland is sometimes difficult because it involves dealing with commercial forces, but some efforts like those in Tokyo and Oregon have been successful.