高位收穫田の化學的研究 : 其の三 大阪府下に於ける高位收穫田の調査並に研究 : 其の四 兵庫縣下に於ける高位收穫田の調査並びに研究(農藝化学)

摘要

The differences between the representative fertile paddy soils and their neighbouring infertile soils in Osaka and Hyogo Prefectures were investigated in the field and laboratory. The results may be summariesed as follows: (1) The average depth of cultivating layers of fertile fields was 17cm., while that of infertile fields was 11.9cm. (2) The compact layers which had been caused by plowing fertile rice fields were not hard so that the roots of rice plants can penetrate more or less, but those of infertile fileds were very hard as if a "hard pan". (3) In most cases, the underground water levels of low yield fields were relatively higher than those of high yield fields. (4) The difference of subsoils between these two soil groups was not distinct, but in low yield fields, there is much heavy clay soil in which the penetration of water is very slow. (5) The drying effects of low yield rice fields have a tendency to be greater than those of high yield fields, while the difference of total nitrogen contents between these two fields was insignificant. (6) The free iron contents are generally more in the subsoils than in the surface soils. In many sandy soils, iron is solved away from the surface soils. But any definite difference between the high yield rice soil and the low yield one can not be recongnized, except the soils of Takawashi and Tannan-mura. (7) It was observed that the "total acidity" of high yield surface soils is relatively lower than that of low yield surface soils, while it was reversed in compact layers caused by plowing and in subsoils. The pH values of the surface soils have the same tendency, that is, greater in high yield fields than in low yield fields. But any defiinite differences were not observed in compact layers caused by plowing and in subsoils. (8) The definite differences between high yield rice fields and law yield ones in ignition loss, base exchange capacity and etc., could not be recognized.