|
Maintaining adequate supplies of food and fiber to meet the needs of the human population is essential to sustainable development. Crops, forage plants, and trees are our main sources of food and fiber, and excessive soil erosion can have an adverse effect on agricultural productivity and communities (e.g., as occurred during the Dust Bowl of the 1930s). It will become increasingly important to protect the soil from erosion due to the rising food needs of the world’s growing population and the potential impacts of global climate change on agricultural patterns.
While soil erosion occurs naturally on all land, at least 40% of the total soil erosion in the United States results from non-agricultural activities such as construction, logging, and off-road vehicle use, or from natural events such as floods and droughts. Erosion reduces soil productivity and can affect the quality of both air and water resources. A limited amount of soil erosion is tolerable in terms of soil productivity, and this tolerable level of erosion (T) varies with factors such as soil type and the time required for new soil to form.
Soil erosion rates greater than the tolerable level can threaten agricultural productivity. Sheet erosion and rill erosion tend to be a greater problem in the humid East than elsewhere in the country, while wind erosion is a greater problem in the arid and semi-arid West. Estimates of streambank, gully, irrigation-induced, and ephemeral gully erosion are not currently included in standard soil erosion assessments, although such forms of erosion can be substantial in certain situations.
In 1982, erosive forces moved nearly 3.1 billion tons of soil from our Nation’s cropland (1.4 billion tons via wind and 1.7 billion tons via water). In 1992, erosive forces moved nearly 2.1 billion tons of soil from our Nation's cultivated cropland. About 1 billion tons less than were moved in 1982--About 0.9 billion tons from wind erosion and 1.2 billion tons from sheet and rill erosion. Between 1982 and 1992, the number of cultivated cropland acres where sheet and rill erosion and wind erosion were occurring at levels above the tolerable rate (T) declined by 5.5% and 5%, respectively.
Link(s) to be added, when feasible, to data at level of detail suitable
for use at the community level.
|
http://www.sdi.gov/indicators/lc_erosn.htm Last Modified: May 13, 2002 |