黒ボク土における作土層の深さが作物収量と土壌の理化学性に及ぼす影響

抄録

1. The effect of combination of cultivated soil depth and amount of fertilizer on vegetable crops yield and soil The experiments had two levels of fertilizers, standard and 1.5 times the standard, and three levels of cultivated soil depth, 15cm, 25cm and 40cm. 1) The yield of broccoli {Brassica oleracea L.) was larger in the deep cultivated soil plots, but yield was decreased in the 1.5 times fertilizer plot. 2) The yield of Komatsuna (Brassica rapa L.) in the deep cultivated soil plot with the standard fertilizer was greater than 1.5 times fertilizer plot. 3) In the 1.5 times fertilizer plots, leaching of CaO and MgO was high, pH of soil was low, and the EC was high. 4) Available P was lower in the deep cultivated soil regardless of the amount of fertilizers. 6) In cultivated soil depth of 15cm and 25cm, It was suggested that standard fertilization quantity was too many. 2. The effect of combination of cultivated soil depth and a low amount of fertilizer on vegetable crops yield and soil. The experiments had two levels of fertilizers, standard and 0.8 times the standard, and three levels of cultivated soil depth, 15cm, 25cm and 40cm. 1) Cucumber (Cucumis sativus L.) was increased the yield from the 0.8 times level in the shallow cultivated soil plots, but the yield in the deep cultivated soil was higher in the standard fertilizer. 2) The yield of broccoli in the 0.8 times fertilizer plot was larger in the shallow cultivated soil plots, and did not differ much in the deep cultivated soil plot. 3) The EC value did not differ much in the cucumber experiments, but they were clearly higher in the 0.8 times fertilizer plots in broccoli. 4) Available P, pH and the bases tended to be higher in the shallow cultivated soil plots. 5) Available P and the bases were low in the 0.8 times fertilizer plots, but they tend to be accumulated in the standard fertilizer plots.