本邦土壌膠質物の研究 第2報 : 土壌膠質物の燐酸含量に就て

抄録

1. The analyses of the total P_2O_5 were made on the so-called susdensoid and emulsoid clays which were obtained from 50 uncultivated residual soils of various geological and petrographical origins. 2. For the determination of P_2O_5 in the suspensoid clay, the Na_2O_2 method was employed. In the case of the emulsoid clay, however, the conc. HCl method was nsed ; because, the latter method gave the same figures as resulted by the Na_2O_2 method. 3. The amount of P_2O_5 obtained, varied with the nature of the soil, ranging from 0.19 to 0.48% in the case of susbensoid clay, and 0.14 to 0.30% in the case of emulsoid clay. The average amounts, and mean and probable deviations are as follows : [table]4. Comparison of the emulsoid clays with the corresponding suspensoid clays shows a fairly marked diminution of total phosphoric acid. 5. Generally speaking, the soil colloids which were derived from the volcanic ashes and metamorphic rocks, show the presence of comparatively large amount of P_2O_5,whereas those of tertiary and mesozoic origins contain its relatively small quantity.