POWER REQUIREMENT OF A BENTLEG PLOW AND ITS EFFECTS ON SOIL PHYSICAL CONDITIONS

A 30^degree left hand facing bentleg plow (BL) was used to subsoil a moderately compacted clay-loam soil at three different depths (250, 350 and 450 mm) and three rake angles (7.5^degree 15^degree and 22.5^degree). The tractor forward speed was maintained at kM hr^-1 The power requirement and changes in soil physical conditions were measured and compared to those of a moldboard plow (MB) at 250 mm working depth. Draft was significantly affected by both BL characteristics and was minimum at rake angle of 7.5^degree. Draft unit^-1 of width of BL plow was 0.5, 1.0 and 1.4 times that of MB plow at working depths of 250, 350 and 450 mm, respectively. BL plowing decreased the soil bulk density from 1280-1500 to 1000-1350 kg m^-3 for the depth range studied. Increase in cumulative water infiltration up to five times that of before tillage (BT) conditions and two times that of MB plowing was achieved by BL plow. The BL plow left 74% of surface residue undisturbed compared to 16% by MB plow. The cross-sectional area tilled by BL plow was larger compared to MB plowing and increased uniformly in all directions as depth was increased. The specific draft of the BL plow tilling at the depths of 250, 350 and 450 mm were 30, 46 and 40% that of MB plow, respectively. The power requirement for subsoiling with a BL plow was less than that for MB plowing and therefore it was within the capacity of most common tractors in local farms. The low power requirement and great improvement in soil physical conditions would suggest application of the new BL plow in many of the soils suffering from moderate to excessive compaction.