Impacts of Productivity Loss on Crop Production and Management in a Dynamic Economic Model

Abstract

This article finds the optimal choice of tillage method and crop rotation for farmers who correctly anticipate the yield-decreasing effects of soil erosion. Expected increases in crop prices lead to farming practices that are more conservation oriented. Higher relative prices for hay also lead to more soil conservation. A linear programming model of soil loss is presented for a watershed in Tama County, Iowa. Key words: linear programming, soils. A major consequence of more intensive ag-ricultural production has been increased soil erosion from cropland. Soil loss rates that ex-ceed the rates of soil genesis will inevitably reduce soil productivity in the long run. Both the popular press and scientific publications contain expressions of concern that cropland erosion will threaten our ability to meet long-run demands for food at reasonable prices. Given the current state of knowledge, crop-land erosion rates in the major crop-producing regions exceed the rates of topsoil genesis. Eventually, these positive net erosion rates will reduce the productivity of the cropland resource. Although this statement may point to a potential cropland crisis, four important qualifications need to be introduced. First, the empirical relationship between loss of topsoil and topsoil productivity is not well estab-lished. Second, information on soil genesis is even more scarce, but rates up to five tons per acre per year are frequently used (Cook)