CROP PRODUCTION, SOIL EROSION, AND THE ENVIRONMENT IN THE MAUMEE RIVER BASIN: A MODELLING APPROACH

Sediment from agricultural cropland has widespread economic, physical, and chemical impact affecting many social and economic groups. It is estimated that sediment causes pollutant damage costs of at least {dollar}1 billion annually.; The focus of this study was on estimating some sediment damage costs, determining the economic impact of soil management practices, and examining the impact on farm income of policy options to reduce soil erosion.; In particular, the impact on drainage ditch dredging and water treatment costs of soil loss from crop production was estimated. The impact on farm income of reduced tillage practices, restricting soil erosion to soil loss tolerance levels (T-values) and beyond, and imposing soil loss tax was analysed. The study was applied to the Maumee River Basin in Northwestern Ohio, probably the most intensively cultivated part of the State.; Statistical estimation procedures were used to determine the soil loss damage costs. A Cobb-Douglas sediment production function was used to determine the relationship between soil erosion from cropland and sediment deposition in drainage ditches. The Universal Soil Loss Equation (USLE) was used to calculate soil loss. Similarly, a Cobb-Douglas cost function was applied to test the relationship between soil erosion from cropland and municipal water treatment cost.; A linear programming model was used to determine the impact on farm income of reduced tillage practices, soil loss restrictions, and soil loss taxes. Some 2.6 million acres, five major crops (corn, soybean, wheat, oats and hay), three tillage practices (conventional, minimum, and no tillage), and five soil management groups were modeled into the mathematical model.; Results indicate that soil loss rates determined using the USLE are significantly related to sediment deposits in drainage ditches. Furthermore, soil loss from cropland was found to increase significantly the cost of municipal water treatment. Reduced tillage practices increased farm income by about four percent while restricting soil loss to T-values had very little effect on income. In fact, soil loss can be restricted up to 0.4T without any substantial loss in farm income. Imposing a soil loss tax equivalent to the estimated soil loss damage costs ({dollar}5.00 per ton) decreased farm income by about 5.3 percent.