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TYPES OF SOIL EROSION
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Soil erosion is caused by wind and water.
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Wind erosion: the soil is detached, transported, and deposited by wind.
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Sheet erosion:
the removal of a fairly uniform layer of soil from the land surface by the action of rainfall and surface runoff.
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Rill erosion:
the formation of numerous small waste channels, which are only a few inches deep.
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Gully erosion:
an advanced state of rill erosion in which water accumulates in channels and washes away soil to depths ranging from 1 or 2 feet to as much as 75 to 100 feet.
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Streambed erosion: the widening of streams due to water flow and soil loss.
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Sources: Nancy Blanpied, editor, Farm Policy: The Politics of Soil,
Surpluses, and Subsidies [Washington, D.C.: Congressional Quarterly, Inc., 1984],28; NRCS, Texas Summary Report 1992 National Resources Inventory [Washington,
D.C., 1997].
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Soil erosion levels vary among types of soil. Some erosion is caused by
nature and is therefore inevitable, but erosion is also the result of human actions. The amount of soil erosion that most cropland can tolerate without reducing production is termed
by the USDA the "T" factor. In Texas, the "T" factor for most cropland is about five tons of soil per acre per year. That is, cropland can lose five tons per acre per year for an
indefinite period of time without sacrificing productivity. The objective of conservation abatement programs
and practices is to bring erosion levels down to or below this "T" factor.
- Of the approximately 30 million acres of cropland in Texas, the National Resources Conservation Service
estimated that over 36 percent was highly erodible and that 68 percent could benefit from some form of conservation treatment or abatement programs.*
- Texas leads the nation in the number of tons of eroded cropland soil,with an average of approximately 326
million tons of cropland soil lost annually (approximately 13 tons per acre),*
- Water erosion is the primary concern for the central and eastern parts of Texas. Wind erosion is the primary
concern in far west Texas and the Plains region. Both wind and water erosion are concerns in the Rolling Plains and in the southern parts of the state
- From 1986 to 1996, Texas producers, under the Conservation Reserve Program, received approximately $164
million in rental fees and approximately $100 million in cost sharing in return for taking 3.9 million acres out of production and converting that acreage to grass, legumes, and trees.
- Texas had more land in the CRP program than any other state from 1986 until 1996. (This is expected due to
the large amount of agricultural land in Texas)
- More than 80 percent of the CRP acreage in Texas, as well as 60 percent of the participating farmers, are in the
High Plains and Rolling Plains regions.
- As of August 2002, Texas again led the nation in the amount of acreage in the Conservation Reserve
Program---4,037,445 acres in the CRP.
- Of the 30.1 percent of the Texas rivers and streams that have been assessed and classified as impaired,
agriculture sources have been identified as causing ten percent of known sources of pollution.
- Of the 38.2 percent of the Texas lakes/reservoirs that have been assessed and classified as impaired, non-point
source runoff from irrigated crops have been identified as causing 14 percent of the known sources of pollution.*
- Both agricultural nitrates and pesticides have been found in groundwater in Texas.
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HIGHLY ERODIBLE CROPLAND IN TEXAS BY WATERSHED
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The USDA Natural Resource Conservation Service
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