A recent USDA study indicates that conservation practices applied to Midwestern cropland are reducing sediment, nutrient and pesticide losses from farm fields.
The study examined the effects of conservation practices on environmental quality in the Upper Mississippi River Basin (UMRB), which covers about 121.5 million acres between north-central Minnesota and the confluence of the Mississippi and Ohio rivers. The basin includes large portions of Illinois, Iowa, Minnesota, Missouri, Wisconsin and portions of Indiana, Michigan and South Dakota. Nearly half of the basin is planted in corn and soybeans.
The comprehensive study found that:
- Use of soil erosion control practices is widespread, but the most vulnerable acres require additional conservation practices.
- Complete and consistent use of nutrient management practices is generally lacking; 62% of the acres require additional treatment to reduce the loss of nitrogen or phosphorus from farm fields.
- The most critical conservation concern is the loss of nitrogen through leaching on half of the cropped acres.
- Treatment of erosion alone can exacerbate the nitrogen leaching problem by rerouting surface water to subsurface flow pathways.
- Nitrogen leaching loss is controlled by pairing erosion-control practices with nutrient management practices for rate, form, timing, and method of application.