CHANGE IN SOIL MICROTOPOGRAPHY BY TILLAGE WITH A SWEEP

Information on effects of tillage sweep geometry and operation on soil conditions, including soil surface elevation, is needed for effective design, selection, and use of sweeps for row crop cultivation and rid ge construction. The effects of sweep rake angle and of operation spee d and depth on changes in soil microtopography were determined Changes in microtopography due to observed soil aggregate movement were also found A factorial arrangement of pairs of sweeps with three geometries operated at three speeds (5, 7, and 9 km/h) and at two depths (50 and 100 mm) were used to form ridges in a field experiment. Soil shift, o r lateral soil movement, and ridge height were affected by both tool o perating speed and sweep rake angle. Faster speeds and steeper rake an gles created larger ridges. Change in surface height, an indicator of soil loosening, was significantly affected by tool depth and speed, bu t not by sweep rake angle. Deeper operation created a higher soil surf ace. The lateral movement of soil into the ridge was more closely rela ted to vertical movement of soil on the tool than to lateral soil move ment on the tool.