Soil formation from the underlying bedrock may proceed ten times more slowly. If these scientists are correct, we are mining the soil on most of our cropland. In some areas we are already experiencing lower yields due to erosion and the reduction in fertility it causes. Adding wind erosion may increase that estimate by 30 percent. Yet farmers are still getting 90 to 95 bushels of corn an acre.
Farmers don t believe they are losing productivity.
They use chemicals to make up for the soil s lost natural fertility, but the cost of fertilizer has risen 200 percent since 1967 and is likely to keep rising. Higher production costs must ultimately mean higher food prices. Moreover, the soil washed from farmlands ends up in rivers, streams, and reservoirs. The government estimates that 43 percent of the land used for row crops in the Corn Belt is composed of highly erodible soils. By 1975 the total real value of soil conservation improvements had deteriorated over 20 percent from its peak in 1955.