USING CREAMS AND ECONOMIC MODELING TO EVALUATE CONSERVATION PRACTICES - AN APPLICATION

Economic modeling of the impacts of soil loss from agricultural activities traditionally has been based on the Universal Soil Loss Equation (USLE). Most studies have not considered the effects of agricultural production on N, P and pesticides in runoff. This study, involving a representative Pennsylvania [USA] dairy farm, used the CREAMS model (Chemicals, Runoff and Erosion from Agricultural Management Systems) to estimate surface runoff losses of soil, plant nutrients and pesticides. The CREAMS was a continuous simulation model that allowed the user to compare the effectiveness of management practices for reducing these losses in a consistent and comprehensive manner. The usefulness of the CREAMS simulation model was demonstrated for analysis of agricultural cropping activities and their impacts on losses of chemicals and soil in runoff. Linear programming was used to simulate the impacts of farm-level water pollution restrictions on farm income. Nonpoint source pollution was reduced without necessarily reducing farm income. Farm income levels could be maintained by adopting conservation tillage practices or by changing crop rotation. Conservation tillage was the most effective method for maintaining income when water pollution restrictions were imposed. Two yr of corn (Zea mays) followed by 3 yr of alfalfa (Medicago sativa) was a profitable and effective rotation for controlling runoff losses. Continuous corn caused substantial losses of income when restrictions were imposed.