土壌コロイドの構造に関する研究(第3報) : 水田土壌について

抄録

In this paper, the sedimentation volume and the colloidal state of water-logged paddy soils were investigated. It was welltimed to measure the sedimentation volume 2 hours (5 hours in special case) after shakig the plugged glass tube. The coagulation degree of water-logged paddy soils were measured by the apparatus showed in Fig. 1. Fe^<II> ions, formed in the reductive layer, decreased the negative charge of soil colloids as the bivalent positive ions. So in the cases of normal paddy soils, which contained a large amount of free iron, the soil colloids in reductive layer were in the jelly state, and soils were brought to be coagulated solidly. On the other hand, in the cases of aged paddy soils, which contained a small amount of free iron, the soil colloids were in the sol state, and the soils were not to be coagulated as the former due to the action of H_2S.