Tolerable Erosion Levels | Minnesota NRCS

"T" value, soil loss tolerance, assigned to each soil map unit, is the average annual erosion rate (tons/acre/year) that can occur and still permit a high level of crop productivity to be sustained economically and indefinitely.
	Estimated average annual sheet and rill erosion in relation to "T" value on cultivated cropland has declined from 1982 values. In 1982 12.7% of the total cultivated cropland was eroding at an annual rate above the tolerable level ("T"). In 1997 acres of cultivated cropland eroding above the tolerable level decreased to 9.4% of the total.
	In 1997 the 1,845,500 acres of cultivated cropland that may be eroding above the tolerable level (9.4% of the cultivated cropland acres) accounted for 45% of the Universal Soil Loss Equation (USLE) estimated annual soil loss.
	Estimated average annual wind erosion in relation to "T" value on cultivated cropland is essentially at the same level as in 1982 despite slight increases in the interim. Over 42% of the 1997 total cultivated cropland has an estimated wind erosion rate above the tolerable level.
	The 42% of the cultivated cropland acres that have the potential for wind erosion above the tolerable level (8,309,300 acres) account for a startling 82% of the Wind Erosion Equation (WEQ) estimated annual soil loss.

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