The nation's concern about soil erosion has focused on tillage practices used to produce row crops. Because of this concern, legislation now requires grain producers to adopt soil conservation practices if they want to participate in many government programs. The 1985 Farm Bill's conservation provisions classify soils into different erodibility categories. Soils designated as "highly erodible" must have an approved conservation plan if the producer wants to plant crops on them as part of a government program's acreage base.
On what basis is a soil determined to be highly erodible? Experience and common sense point out that several factors such as rainfall intensity, soil properties, slope, crop and tillage system affect soil erodibility. After many years of research aimed at quantifying the combined effect of these factors, an equation was developed to help predict soil erosion losses. The Universal Soil Loss Equation (USLE), developed at the National Runoff and Soil Loss Data Center, incorporates environmental and topographic factors affecting soil erosion. It predicts how much erosion a given site will have in terms of tons/acre/year.
Ditsch, David C. and Murdock, Lloyd, "Soil Erodibility: How Is It Determined and Used?" (1987). Agriculture and Natural Resources Publications. Paper 31.