Fundamental studies on the action of plowing machine Part I Studies on the mechanical analysis of soils (No 1)

The writer has been pursueing a comparative studies on several methods for making mechanical analysis of soils since last year. The methods criticized in this report are the ASK method, Hydrometer method and Beaker method. The soil used for the experiments was a heavy clay from (Asa, Yamaguti Prefecture. The ASK method, an improved Kopecky method and commonly used in Japan, excels in the simplicity of operation. Once the exact velocity of flow of water through two tubes has been ascertained, the apparatus is able to be left alone. Moreover, the current serves to prevent it from the flocculation of the soil and to hold loosely the aggregates. But there might be discovered several remarkable defects of ASK method in respect of mechanical analysis. It is difficcult to regulate the flow of water through the various tubes and to ascertain whether the velocity in the given tubes is desirable. Serious convection currents are to happen in all the tubes. The grain size accumulation curves were plotted, and obtained by plotting the diameter of soil grain on the logarithmic abcissa and the summation percentage on the ordinater, in order to compare with the differences within the results obtained by these methods.