1992
data collected for the National Resources Inventory (NRI) show the statewide
average soil erosion loss still exceeds 6 tons per acre per year, and many areas
have loss rates as high as 25 tons per acre per year. 1992
data collected for the National Resources Inventory (NRI) show the statewide
average soil erosion loss still exceeds 6 tons per acre per year, and many areas
have loss rates as high as 25 tons per acre per year.
Loss of part of an ecosystem affects everything else in that system. This can be seen with the disappearance of natural riparian zones, which has resulted in increased non-point source (NPS) pollution of surface and ground water, streams that are wide, deep and flood-prone, and loss of wildlife habitat throughout the Midwest. This loss of buffer protection contributes to serious environmental problems.
Increased soil erosion
In Iowa, 1992 data collected for the National Resources Inventory (NRI) show the statewide average soil erosion loss still exceeds 6 tons per acre per year, and many areas have loss rates as high as 25 tons per acre per year. These same soils would lose only 200 to 400 pounds per acre per year if covered with natural forest or prairie vegetation. In the Midwest, it is common to have more than 90 percent of a watershed used for row crop agriculture. Many areas, where farmers have used conservation practices such as reduced tillage, grassed waterways, strip or contour cropping, and terraces on at least 40 percent of the land, still experience some of the highest erosion rates.
Significant gains have been made in Midwestern agricultural practices that reduce soil erosion, but the biggest NPS pollutant to enter streams is soil sediment from erosion. This loss of soil and reduction in water quality from NPS pollutants produce agricultural systems that are not likely to show long-term sustainability on certain soils and landscapes.
Loss of habitat
As human population and living areas increase, wildlife is squeezed into ever smaller patches of habitat. In the Midwest, where only one in 10 acres is not used for either crop or pasture production, additional habitat can be critical to certain game and non-game wildlife species. Tile drainage that increased the amount of tillable land and allowed for bountiful harvests has dramatically reduced wildlife abundance and diversity. In North Dakota, 60 percent of the natural wetlands have been drained, compared to 90 percent lost in Iowa to agriculture and other uses.
The loss of these wetlands has removed natural ecosystems that were capable of supporting many wildlife species, reducing excess nutrients, degrading pesticides that move through a watershed, and of acting as "sponges" to reduce flooding. Where wetlands have been allowed to develop again naturally or be restored under programs such as the Wetland Reserve Program (WRP), wildlife have flourished.