Changes in soil microtopography by tillage with a cultivator sweep

An experiment was conducted to determine the effects of sweep rake angle, speed, and operating depth on changes in microtopography. Such information is useful in sweep design and operation for ridge tillage. Parameters describing microtopography changes.are lateral soil shift, ridge height and change in mean surface height. A factorial arrangement of three pairs of sweeps operated at three speeds (5, 7 and 9 km/hr) and two depths (50 and 100 mm) were used to form ridges in five field blocks of varying moisture and soil type. Soil shift and ridge height were affected by both speed and tool geometry (a = .01). Higher speeds moved more soil into the ridges. A modified sweep with rake angle of 44° produced greater soil shift and higher ridges than the commercial sweeps with rake angles of 13.5° and 16° (a = .01). Comparing commercial sweeps, the 16° sweep produced a higher ridge (a = .05) and greater soil shift (a = .10) than did the 13.5° sweep. Change in surface height was significantly affected by tool depth (0£ = .01) and speed (a = .05) but not by tool geometry. Deeper operation created a higher soil surface. The relationship of change in surface height to speed was quadratic (a = .01).