. The changing Illinois environment : critical trends : technical report of the Critical Trends Assessment Project. Man; Pollution; Environmental protection; Ecology; Environmental impact analysis. Figure 21. Percent decrease in farmland grazed, 1964 to 1987. Source: Department of Commerce, Bureau of the Census. Figure 22. Percent decrease in woodland grazed, 1964 to 1987. Source: Department of Commerce, Bureau of the Census. amounts of active ingredients applied in corn and soybeans (lb/acre) have been decreasing since the late 1970s (National Research Council 1989). Knowing how muc
. The changing Illinois environment : critical trends : technical report of the Critical Trends Assessment Project. Man; Pollution; Environmental protection; Ecology; Environmental impact analysis. Figure 21. Percent decrease in farmland grazed, 1964 to 1987. Source: Department of Commerce, Bureau of the Census. Figure 22. Percent decrease in woodland grazed, 1964 to 1987. Source: Department of Commerce, Bureau of the Census. amounts of active ingredients applied in corn and soybeans (lb/acre) have been decreasing since the late 1970s (National Research Council 1989). Knowing how much active ingredient is applied per treatment per acre and how many treatments and acres are involved is critical to understanding contamination by pesticides. Unfortunately, this information is not currently available for Illinois farmland. In general, the toxicity of pesticides and their metabo- lites to nontarget organisms, and indirect effects, remain poorly understood. A plethora of compounds are used, and the list of approved compounds continues to increase. Trends in Nitrogen and Soils Illinois has the best soils for crop production in the world. However, because of soil type and slope of the land, many farms have highly crodiblc soils (Figure 17). Erosion by wind or water runoff moves soil around the same farm, from farm to farm, and from farm to streams and lakes. Sedimentation of water resources is a major problem in Illinois (see chapter in this volume on lakes and impoundments). At present, Illinois has one of the highest rates of inorganic fertilizer application in the Midwest. Since 1982, nitrogen, phosphorus, and potassium fertilizer use has been approximately 150, 80, and 80 pounds per acre, respectively, in Illinois, according to the Illinois Department of Agriculture. Field corn receives the vast majority of the nitrogen fertilizer. Figure 26 shows how fertilizer use has changed over the past 30 years in the counties of Illinois. Extensive use of inorganic fert
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