MODELING CORN GRAIN-YIELD IN RELATION TO SOIL-EROSION USING A WATER-BUDGET APPROACH

The effect of long-term soil loss on corn (Zea mays L. ) grain yields in shallow soils of the Northeast is evaluated using a simple computer simulation model. Easily obtainable soil and meteorological data are used as input. The model relates the change in soil productivity to the reduction of available water holding capacity caused by long-term soil loss by erosion. Depth to an impermeable layer, which limits the total available water in the soil profile, is considered a nonrenewable soil property. Renewable soil properties such as surface soil structure and fertility, which can be maintained through optimum managment, are not considered to limit yields. The model is based on the established relationship between relative yields, and the relative transpiration ratio.