. The changing Illinois environment : critical trends : technical report of the Critical Trends Assessment Project. Man; Pollution; Environmental protection; Ecology; Environmental impact analysis. AGRICULTURAL LANDS from production under annual contract has achieved soil and water quality goals has not been monitored. Since World War II agriculture has moved from relatively small, diversified farming systems to large, highly specialized cash grain units. As cropping systems have changed in recent decades, key animal, mechanical, and chemical disturbances have also changed. Crop rotations that
. The changing Illinois environment : critical trends : technical report of the Critical Trends Assessment Project. Man; Pollution; Environmental protection; Ecology; Environmental impact analysis. AGRICULTURAL LANDS from production under annual contract has achieved soil and water quality goals has not been monitored. Since World War II agriculture has moved from relatively small, diversified farming systems to large, highly specialized cash grain units. As cropping systems have changed in recent decades, key animal, mechanical, and chemical disturbances have also changed. Crop rotations that traditionally included soil- building forage legumes and small grains have dimin- ished (Figure 7) as the production of corn and soybeans (row crops) has increasedâa trend that has been particularly important since the early 1960s (Figure 8). Since 1964, the amount of land planted in soybeans has increased dramatically in most counties (Figure 9), while the changes in corn acreage have been more varied (Figure 10). Rotation of corn and soybeans every other year is good for pest management, but soybean production can increase soil erosion. Compar- ing county-level trends from 1964 to 1987 shows that production of oats has generally increased, especially in the southern half of Illinois (Figure 11), while production of hay has generally declined (Figure 12). However, oat plantings in 1987 were unusually high because 30% of the corn base was diverted from crop production that yearâmost of which was planted to oats. Wheat production was lower in 1987 than in 1964 except in the extreme northwest and south (Figure 13). Because of this expansion of soybean and corn production, mechanical disturbances of the soil have greatly increased since World War II. Fall tillage (using primarily the moldboard plow) increased from the early 1950s through the late 1970s (Figure 14). Conservation tillage, which is defined as at least 30% of the soil surface protected by crop stubble after spring
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