The experiment was conducted at the Purdue University Agronomy Farm during the summer of 1974. Plots with varying amounts of ground cover were established on two different soil types by having seven different plant populations for corn and four different plant populations for soybeans. The two soil types were Russell silt loam and Chalmers silty clay loam. The corn populations were 0, 15, 30, 45, 60, 75, and 90 thousand plants per hectare. The soybean plots were planted with row widths of 25, 50, 75 and 100 centimeters; there were also plots with no soybeans (bare soil). This experiment was a continuation of the 1972 and 1973 Ground Cover Experiments.