TILLAGE AND RESIDUE EFFECTS ON INFILTRATION AND SEDIMENT LOSSES ON VERTISOLS

Management effects on water infiltration in vertisols is not well understood. Rainfall simulators and ponded and tension infiltrometers were used to characterize water infiltration rates as affected by traffic, crop residue, and tillage. Management was characterized by controlled traffic, with wide beds with either no-till or annual chisel-tillage on a Houston Black Clay soil (fine montmorillonitic, thermic Udic Pellusterts), a self-mulching vertisol. Traffic greatly reduced water infiltration rates compared to nontracked areas. Soil disturbance resulting from tillage in nontraffic areas was nor a significant variable in determining water infiltration rates. Rather, tillage effects on surface residue cover were more important in determining water infiltration rates. Surface residue was effective in controlling erosion from the wide bed management practices used in these studies. Erosion losses were greater than 4 t ha(-1) for the wet runs from both the no-till and tilled beds without adequate residue cover. Surface residue reduced erosion losses to less than one-tenth that of an unprotected surface.