Using the erosion-productivity impact calculator (EPIC) model to estimate the impact of soil erosion for the 1985 RCA appraisal

Abstract

ABSTRACT: The U.S. Department of Agriculture developed a sophisticated physical process model to summate the soil-climate-plant-management processes in agricultural production and to estimate the impact of soil erosion on resource productivity and fertilizer requirements for the 1985 Resources Conservation Act appraisal. Estimates from this model, the erosion productivity impact calculator (EPIC), show that if cropping patterns and the mix of management, tillage, and conservation practices inventoried in the 1982 National Resources Innovatory are continued for 100 years, sheet and rill erosion and wind erosion will exceed the erosion tolerance (T) on 127 million acres and 64 million acres, respectively. This rate of soil loss will reduce productivity in the 100th year by an estimated 2.3 percent—the equivalent to taking 7.4 million acres of cropland out of production. Annual fertility requirements are estimated to increase by 798, 672, and 10,920 million pounds of nitrogen, phosphate, and lime, respectively. The present value of this 100-year national loss is about $22 billion.