ABSTRACT
The rate of land use change affecting agricultural lands speeded up in the 1970s. By 1977, there were 90 million acres of urban and built-up areas larger than 10 acres, up from 61 million acres in 1967 and 51 million acres in 1958. In addition to the losses being inflicted on our farm productivity by soil erosion and farmland conversion, there are other resource concerns as well. Soil organic matter levels dropped rapidly in most of the soils in the humid cropping zones such as the Corn Belt after the initiation of cultivation, but recent evidence on those trends is mixed. Under continuous corn, for example, it has been estimated that it would take about 6,000 pounds of cornstalks plowed into the soil to maintain organic matter content. Agriculture is by far the nation's largest single consumer of water, accounting for 83 percent of total use, some 89 billion gallons of water each day.
