Studies on the exchangeable manganese in soils

1. It was studied on the relations between the amounts of exchangeable manganese in soils and concentrations of salt solutions, temperature and time of treatments, the kinds of salts used for extraction and the air drying of samples. According to the results of the studies the determination of the exchangeable manganese in soils was performed as follows: fresh soil samples corresponding to 100 gm. of dry matter were shaken for an hour with 250 cc neutral normal potassium chloride solutions at room temperature and extracted manganeses were determined colorimetrically with periodite method. 2. In the amounts of the exchangeable manganese, soils from the rice field was more than upland field generally and G horizon was more than other horizons. I found no relation between the amount of the exchangeable manganese and the kind of parent material, pH values of soils or total manganese content. 3. The amount of extracted manganese increased with lowering the pH values of extracted solution. But its solubility curves were various figure. 4. The amounts of the exchangeable manganese increased rem a rkably when soils were stood in water lodged conditions.1. 置換性マンガンの定量法について, 浸出液の濃度, 処理温度, 処理時間, 塩類の種類, 土壌の風乾処理の影響等について吟味を行い, 次の定量法を採用した. 土壌乾物100gmに相当する新鮮土に中性の規定塩化カリ溶液250ccを加え室温にて1時間振盪し, その濾液についてマンガンを過沃度酸カリ法により定量する. 2. 置換性マンガンは水田に於いては畑地よりも, またG層に於いては他の層位よりも概してその含量が多い. しかしこの含量と母岩地質系統, pH, Eh, 全マンガン等との相関関係は認められない. 3. 浸出液のpHを低下すればマンガンの溶出量を増加する. その溶解度曲線の形は土壌の種類によつて著しく異なる. 4. 土壌を湛水処理すれば置換性マンガンを著しく増加する