Abstract
In previous paper, I had theoretically introduced the sod plow surface of minimum soil resistance, by assuming the soil had been plasticity and using the calculus of variation. The results of the studies had been as follow; the plow surface had been expressed by the path of furrow slice, and the minimum resistance path had consisted of logarithmic spiral near the share part and of circle near the wing of moldboard. (Fig. 1)
In this paper, I studied experimentally these theories, comparing the soil resistance of theoretically introduced surfaces (one being assumed soil shearing strength τe=0.1kg/cm2 and the other τe=0.07kg/cm2) with two ordinary plow surfaces introduced by circular path of furrow slice, one being same boundary condition to the former and the other Stephens type (Tab. 1, Fig. 2, 3), in some soil conditions (Tab. 2). The experimental results with the analysis of variance, showed that differences of the resistances due to plow shapes were significant in plastic soil and deep tillage depth, and the resistance reduction ratios of the theoretical plow to the plow of circular furrow slice path were between 28.4-10.1% and coincided with numerical analysis of theories.
