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 management, are not considered to limit yields. The model is based on the established relationship between relative yields and the relative transpiration ratio. A simple water budget estimates actual transpiration on a daily basis and calculates stress as a function of relative transpiration ratio. Yields are predicted from total seasonal stress and accumulated heat units. The model has been run using 16 yr of meteorological data to simulate varying climatic conditions, and correlations between actual and predicted yields on deep to moderately deep soils are good. Soil erosion is simulated by removing increments of soil depth. For each soil depth, the model predicts both mean yield and variance. Mean yield values are used to generate productivity curves that graphically depict the relationship between soil productivity and soil erosion. For medium textured soils in New York State, the model predicts that soil erosion will decrease mean yield and increase variability in annual yields when the depth to a root restricting horizon is <70 cm.