Agriculture Also see Forestry, Water, Wetlands, and related tables and figures in Part II. reflected the conversion of 16.2 million acres of cropland to other uses, while 17.6 million acres were converted from other uses to cropland. The environmental consequences of these land-use shifts are also complex. Shifting land from other uses to crop production increases soil erosion and the risk of nutrient and pesticide contamination associated with current agricultural practices. Shifting land from crop production to other uses, on the other hand, increases environmental impacts from nonfarm uses, such as runoff of toxins from roadways and parking lots and vehicle emissions associated with urban development. Since 1985 several hundred million acres of cropland have been idled as a result of conservation provisions in farm legislation. In 1987 alone 76 million acres out of a total cropland base of 321 million acres were idled under Farm Bill conservation and supply-control provisions. In 1992 a total of 54 million acres were idled out of the 343 million acres of crop acreage base. This = Note: CRP Conservation Reserve Program. The legislative mandate for combined CRP and Wetlands Reserve Program (WRP) enrollments is 40 million to 45 million acres by the end of 1995. CRP enrollments last for ten years, hence these lands could lose protective status in future years. Source: See Part II, Table 48. figure includes acreage enrolled in the Conservation Reserve Program. Policies and Programs Federal farm legislation in 1985 and 1990 linked farm program benefits and the conservation of natural resources. The Department of Agriculture (USDA) conducts conservation programs to reduce soil erosion, protect wetlands, maintain and enhance wildlife habitat, and improve water quality, while achieving supply-control and income-support objectives in a costeffective manner. Conservation Compliance The 1985 Farm Bill contained conservation compliance provisions that require farmers to develop and imple ment approved conservation plans on highly erodible cropland by 1995. Farmers who do not implement conservation plans lose USDA program benefits. As of July 1992 field personnel of the USDA Soil Conservation Service had helped 1.3 million farmers develop compliance plans that will reduce erosion on 135 million acres of highly erodible cropland. These plans call for 215,000 miles of terraces, 1.3 million acres of grassed waterways, 4,200 miles of erosion-control diversions, cropland contour farming on 25 million acres, and cropland conservation tillage on 100 million acres. As of July 1992 farmers had implemented conservation plans on over half the acres requiring conservation practices. To bolster conservation compliance, USDA supports alliances among agricultural businesses, commodity 1986 1987 1988 1989 1990 1991 Source: See Part II, Table 48. groups, grower associations, and the farm news media. These alliances encourage conservation practices such as leaving crop residue on the soil surface during critical erosion periods. Farmers have chosen some form of crop residue management on 75 percent of the highly erodible land in compliance plans. Working with the alliances, USDA provides technical information and assistance through demonstrations, direct mail, brochures, workshops, advertisements, and features in the farm-oriented media. Conservation Reserve Program The Conservation Reserve Program (CRP) offers farmers an incentive to remove highly erodible cropland and other environmentally sensitive land, such as wetlands, from production for at least ten years. Farmers who enroll in the program receive ten annual rental payments for idling the land and costshare help in establishing a cover of grass or trees. Producers who plant hardwood trees or construct wildlife corridors, windbreaks, or shelterbelts may request contracts up to 15 years in length. As of August 1992 farmers had enrolled 36.5 million acres in the pro gram, resulting in numerous environmental benefits. Average soil loss on CRP lands has declined to one-tenth of the former rate, from 21 to 2 tons per acre per year. Farmers are planting 2.4 million acres in trees; 31 million acres are in grass, predominantly in the prairie and Great Plains region; and another 2 million acres are in plantings beneficial to wildlife. In 1989 farmers entered 410,000 acres of farmed wetlands in the program. In the prairie pothole region of North and South Dakota, during one sign-up period alone, the program enrolled 150,000 acres of farmed wetlands. Under one program option, 13,000 acres of shallow-water wetlands are being restored. Eligibility has been extended to saline lands and to cropland that contributes to water quality degradation. Incentives encourage the planting of hardwood trees in woodland, windbreaks, shelterbelts, and wildlife areas. A total of 23 U.S. watersheds, including the Chesapeake Bay and the Great Lakes, are designated Conservation Priority Areas and, as such, receive preference in program enrollments. In addition to reducing soil erosion, CRP reduces pesticide use on land enrolled in the program by an estimated 30,000 tons annually and fertilizer use by an estimated 2.4 million tons annually. Because CRP may create an incentive to increase the intensity of fertilizer and pesticide use on remaining cropland, however, the net reduction in fertilizer and pesticide use may be smaller than these estimates suggest. Swampbuster The 1985 Farm Bill took major steps to slow the loss of ecologically valuable wetlands in the United States. Producers who convert existing wet |