TILLAGE AND RESIDUE EFFECTS ON INFILTRATION AND SEDIMENT LOSSES ON VERTISOLS

Management effects on water infiltration in vertisols is not well unde rstood. 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 Pell usterts), a self-mulching vertisol. Traffic greatly reduced water infi ltration rates compared to nontracked areas. Soil disturbance resultin g from tillage in nontraffic areas was nor a significant variable in d etermining water infiltration rates. Rather, tillage effects on surfac e residue cover were more important in determining water infiltration rates. Surface residue was effective in controlling erosion from the w ide bed management practices used in these studies. Erosion losses wer e greater than 4 t ha(-1) for the wet runs from both the no-till and t illed beds without adequate residue cover. Surface residue reduced ero sion losses to less than one-tenth that of an unprotected surface.