PM—Power and Machinery: A Three-stage Soil Layer Mixing Plough for the Improvement of Meadow Soil, Part 2: Soil Bin Experiments

Abstract The objective of this work was to develop a special machine, a three-stage soil layer mixing plough which would achieve longer sustainability of drainage for the improvement of meadow soil. In this paper, the results are presented from soil bin experiments with the three-stage soil layer mixing plough, that were conducted in Japan with the half-scale model ploughs. An optimum plough shape of the second plough body was determined, based on the mechanical properties of the soils presented in Part 1 of this paper. The results showed that the operating depth of the second plough body is small but the operating width is large and the plough body should transfer the tilled soil to the preceding furrow over a large distance of the full furrow width. The bulldozer blade type of plough body was much superior to the mouldboard plough type version. When the working depth of the second plough body is 50 mm, the radius of curvature should be 200 mm, the plough height 300 mm and the throwing angle 60°. When the approach angle was more than 45°, the transferred soil masses reached a constant value and, hence, the minimum approach angle at which the soil starts slide horizontally was experimentally around 45°. When the cutting angle was more than 30°, the draught increased steeply and was unsuitable for practical use. Hence, in this model second plough body, the optimum cutting angle should be 30°, even though the suction here is slightly negative.