Productivity of soils: Assessing long-term changes due to erosion

ABSTRACT: An approach to evaluating the long-term effects of erosion on the productive potential of the U.S. soil resource base is presented. This approach involves the application of a numerical index method for quantifying productivity to soil and land use data bases compiled by the Soil Conservation Service. The relative productive potential of soil was evaluated in terms of the environment it provides for root growth based upon the soil9s available water capacity, resistance to root growth and development, and adequacy of pH to a depth of 100 centimeters (39.4 inches). The productivity of soils in Major Land Resource Area (MLRA) 105 in Minnesota now and after 25, 50, and 100 years of erosion was calculated using erosion rates reported in the 1977 National Resource Inventory. The results indicated that the weighted average reduction in soil productivity was less than 5 percent for soils in this MLRA, with the greatest reduction occurring on soils having slopes that exceed 6 percent.