Studies on the relation between the changes of soil moisture and the crop growth on the field used after the pasture cultivation (Report 2)

Abstract

This experiment was carried out from June to October, 1952, to get the effects on growth and yield of sweet potato. After the uniform cultivation of two years we set up the following plots. I. Soybean...pasture (rye grass plus vetch)...sweet potato II. Soybean...wheat...sweet potato plus soybean III. Soybean...wheat...sweet potato 1) Concerning the soil moisfure, at 5cm of depth from the surface, the plot I proved driest and the difference between early morning and evening was greatest of all the plots, but at 20cm of depth the plot I proved wetter than any other plots and the least amplitude of soil moisture was seen. 2) Soil temperature up to 5cm of depth was highest in the plots III and II, and lowest in the plot I. 3) The take-root ratio of sweet potatoes in the plot I showed 95 % and that of the other plot was 1OO%. 4) The surface growth of sweet potatoes in the earlier stage was worst in the plot I, then came the plot II. But since the first the days of August potatoes began to grow suddenly well in the plot I, and at harvest time, the length of vines, the number of branches and the thickness of vines were superior to those of potatoes grown in any other plots. 5) the water-reserve right after rainfall at l0cm of depth and further beneath was highest in the plot I, then came the plot III. But at 5cm deep the plot I rapidly went dry. 6) At harvest time in vine-leaves quantity the plot I produced most, while concerning the weight of tuberous root, the plot III produced most, then came the plot I, and the plot II turned out least. 7) Concerning the potato shape, the plot I produced remarkably longer ones than any other Plots.