PLANT RESIDUE IMPACT ON RAINFALL INTERCEPTION

Rainfall interception by different amounts of corn (Zea mays), soybean (Glycine max L.), and winter wheat (Triticum aestivum L.) residue was studied under simulated rainfall. Given the same amount of residue ma ss, winter wheat residue intercepts significantly more rainfall than c orn and soybean residue. Statistically, corn and soybean residues inte rcept the same amount of rainfall. Age of the residues had no impact o n the amount of rainfall intercepted by the residues. Mathematical rel ationships were derived for estimating rainfall interception rates for different types and amounts of residue. The findings were incorporate d into the Water Erosion Prediction Project (WEPP) computer model to i mprove soil water balance predictions. The model was tested using a 50 -year simulation of the impact of rainfall interception by plant resid ues on the soil water balance of a no-till farm under corn-soybean rot ation near Champaign, Illinois. The results of WEPP model simulations indicate that rainfall interception by crop residues reduces the avera ge annual storm runoff by 13% and average daily root zone soil water c ontent by 9% on a midwest farm under corn-soybean rotation.