What Is This Indicator, and Why Is It Important?
This indicator reports the percentage of U.S. farmlands according
to their potential for erosion by wind or water. These data
are based on an index that combines information on soil characteristics,
topography, and management activities such as tillage practices
and whether crop residue is left on the field or not. This
indicator covers croplands (excluding pastures) and Conservation
Reserve Program (CRP) lands. In addition, those croplands
most prone to wind and water erosion are mapped for 1997.
Agricultural soil erosion reduces soil quality and degrades
water quality. Even relatively small movementsfor example,
from the top of a slope to the bottomcause changes in
soil structure that can reduce fertility and make normal cropping
practices difficult. When soil moves further, eventually ending
up in streams and lakes, it causes water quality problems,
in part because eroded sediments often carry both fertilizers
and pesticides. Even without such pollution, sedimentation
alone imposes significant costs on reservoirs and water treatment
facilities, navigation, and other water and waterway users.
Erosion, organic matter content,
soil salinity, and soil
biological condition are key indicators of soil quality;
changes to crop and soil management practices affect soil
What Do the Data Show? From 1982 to 1997,
the acreage of U.S. farmland with the greatest potential for
wind erosion decreased by nearly one-third, to about 63 million
acres, or about 15% of U.S. croplands. The area with the greatest
potential for water erosion also decreased by nearly one-third,
to 89 million acres, or about 22% of U.S. croplands.
Although both water and wind erosion occur throughout the
United States, high levels of water erosion are more common
in the eastern half of the nation, and wind erosion is more
likely in the West.
Discussion Reductions in erosion can result
from changes in management practices; common practices used
to reduce soil erosion are no-till or minimum tillage, installation
of terraces and field wind breaks, and contour farming. In
addition, removal of highly erosion-prone lands from cultivation,
(for example, enrollment in the Conservation Reserve Program)
typically lowers its erosion potential.