The previous experiment on soil-overturning of rotary tillage was done by using soils mixed with potassium chloride (KC1). This report deals with a soil-overturning experiment which utilizes a method of spraying KC1 solution on the land surface. In this experiment, we measured the electrical conductivity (EC) for clods of each size and discussed the phenomenon of soil-overturning by rotary tillage.
The results were as follows.
(1) The EC values of surface layer, soil layer in which KC1 solution permeated, were the range of 13.7-18.0mS/cm. In the case of an experimental plot, the variation of EC values resulted with the influence of wind.
(2) The thickness of the surface layer was caluculated with EC values of natural and surface soils. It was 3.2-5.6mm thick. In the case of the P2 plot, a signicant difference of the thickness was recognized between the left and right side for spraying direction.
(3) After the investigation on soil displacement of surface layer, we obtained the result which showed deterioration of soil-overturning with the increase of tilling pitch. As this result agrees approximately with the result by a method of soil mixed KC1, the method to use KC1 solution can be also utilized to investigate soil displacement.
(4) From EC value of the clod classfied by size, it becomes clear that generation of the large clod increased around the surface layer before tillage when tilling pitch enlarged. We also confirmed that the large clod increased in upper layer after tillage, according to the increase of tilling pitch. Therefore, the cause on deterioration of soil-over-turning was clarified a little.
