The effect of moldboard plow on tillage erosion along a hillslope

Tillage erosion is considered one of the mast important processes of land d egradation in hilly cultivated areas. Extensive cultivation of hilly areas have largely degraded roil in the Past decades due to the erosion caused by use of heavy powerful tillage implements. In order to evaluate the effect of moldboard plow on tillage erosion, a study was conducted along an intens ively cultivated hillslope (slope gradient from 6-22%) with rainfed crops. Two tillage experiments were carried out, one with the tillage implement mo ving perpendicular and the other parallel to the contour lines. The soil di splacement by tillage was measured by using tracers (numbered aluminum cyli nders of 1 cm(3) volume) that were inserted into the soil at various depths at selected slope positions to give a range of slope gradients. Thirty str ips were prepared and 1200 tracers were inserted into the soil for each exp eriment. The location of each tracer was precisely recorded using a theodol ite before and after the tillage operation. Soil displacement was analyzed for three plow depths (20 cm, 30 cm, and 40 cm) and for two directions of t illage operation in each experiment. The effect of long term moldboard plow ing on tillage erosion in the study hillslope was examined by using past an d present detailed soil survey data, existing water erosion data, and empir ical relationship data derived from this study. Downslope displacement of s oil during tillage increased with increased plow depth and slope gradient. In steep hillslope positions (22% slope gradient), a maximum soil displacem ent of 97 cm was measured after plowing the soil downslope at the depth of 40 cm and perpendicular to the contour lines. After plowing the soil along contour lines, under the same soil conditions, and management practices, so il displacement was reduced to 69 cm. A 50% reduction in plow depth reduced soil displacement by more than 75%. The upslope reversion of furrow with t he tractor moving parallel or perpendicular to the contour lines significan tly reduced soil displacement, from 2-33 cm. The comparison of two tillage experiments showed that contour farming significantly decreased tillage ero sion. The analysis of detailed soil survey data, water erosion data, and ti llage erosion data demonstrated that tillage erosion was the most important process transporting soil from the upper convex to the lower concave parts of the study hillslope.