RAINFALL SIMULATION TO EVALUATE INFILTRATION RUNOFF CHARACTERISTICS OF A SHORTGRASS PRAIRIE

A rotating boom rainfall simulator was wed to evaluate the effects on infiltration and runoff of removing cattle from a native shortgrass ra ngeland site in the Central Great Plains. Study sites included three p astures which had been grazed at the same intensities for 53 years. Af ter 1 year there were changes in the initial dry run equilibrium runof f ratio on the area that had been heavily grazed. No changes were evid ent in the final wet-wet equilibrium runoff ratios after 2 years. Thes e results indicate that changes in the infiltration parameters of the surface soil layers occur within 2 years after removal of cattle grazi ng but no changes occurred at the deeper soil depths, which affect lon g-term equilibrium infiltration. We-wet equilibrium runoff ratios decr eased on the light and moderate grazed areas over the 3-year time span .