A three-stage soil layer mixing plough for the improvement of meadow soil,part 2: Soil bin experiments

The objective of this work was to develop a special machine, a three-stage soil layer mixing plough which would achieve longer sustainability of drain age for the improvement of meadow soil. In this paper, the results are pres ented from soil bin experiments with the three-stage soil layer mixing plou gh, that were conducted in Japan with the half-scale model ploughs. An opti mum plough share of the second plough body was determined, based on the mec hanical properties of the soils presented in Part 1 of this paper. The results showed that the operating depth of the second plough body is sm all but the operating width is large and the plough body should transfer th e tilled soil to the preceding furrow over a large distance of the full fur row width. The bulldozer blade type of plough body was much superior to the mouldboard plough type version. When the working depth of the second ploug h body is 50 mm, the radius of curvature should be 200 mm, the plough heigh t 300 mm and the throwing angle 60 degrees. When the approach angle was mor e than 45 degrees, the transferred soil masses reached a constant value and , hence, the minimum approach angle at which the soil starts slide horizont ally was experimentally around 45 degrees. When the cutting angle was more than 30 degrees, the draught increased steeply and was unsuitable for pract ical use. Hence, in this model second plough body, the optimum cutting angl e should be 30 degrees, even though the suction here is slightly negative. (C) 2001 Silsoe Research Institute.