Japanese Journal of Soil Science and Plant Nutrition

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Soils, different in their chemical constituents, were brought to absorb phosphoric acid and potassium by treating them with M/10 K_2HPO_4 solution. The so composite soil sample, after washed with methyl alcohol until tests with ammonium molybdate gave no precipitate, was taken into the middle chamber or Mattson's Cell and was electrodialyzed for 117 hours; the dialyzate from both chambers anode and cathode were equally renewed 1,4,21,45,69,93,and 117 hours respectively after the beginning of electrodialysis and the so dialyzed amounts of P_2O_5 and K_2O were determined, the former in each acid dialyzate (from anode chamber) after LORENZ method and the latter in each basic dialyzate (from cathode chamber) after cobaltinitrite method. The intensity of removal of absorbed P_2O_5 and K_2O from soils, designated in the ratio of dialyzed amount to that of absorbed, was approximately related to molecular ratios of SiO_2 to Al_2O_3 or Al_2O_3 + Fe_2O_3 of the soils after conc. HCL extraction method; namely, with increasing of the ratios removal of P_2O_5 was inclined to increase and that of K_2O decrease. Absorption of soils is generally considered to be influenced by the concentration and pH of solution besides the physical and chemical constituents of soils. In the case of this experiment also pH of the solution is easily imagined to influence the absorption of soils consequently the removal of P_2O_5 and K_2O from the soils. On the results of determination of pH by test paper method in the middle chamber of cell at the stages of beginning and also of final of electrodialysis, decrease of pH of the solution in the chamber was observed with completion of dialysis and accounted for the fact that the removal of P_2O_5 and K_2O of this experiment was managed under the influence of solution of having a tendency to reduce its pH. As the influence of such a nature as to reduce the pH of solution is expected in the soils of field where the soils have a tendency to become acidic, the results of this experiment will give some of the interpretations on the nature of removal of P_2O_5 and K_2O in the field where the soils have the same tendency.

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In this paper the formation of brown forest soil of limestone origin, distributed on the north of city Genzan (lat. 39°10' N), is dealt with. Notwithstanding the underlying parent rock is limestone, the B-hoizon of soil is acid (pH 4.84) in reaction and extremely poor in exchangeable lime, as a result of heavy washing during the relatively hot and wet summer months. Owing to the deposition of cement dust discharged from adjacent cement factory, the A-horizon was brought to basic (pH 7.63) and calcium saturated state. The silica-alumina ratios of their colloidal clays (<0.001 mmφ) are about 2.6.

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Die Untersuchung des Problems, das schon durch zweimalige Gefassversuche und einmaligen Wasserkulturversuch von Tokuoka und Morooka geforscht worden ist, ist nun wieder durch Wasserkultur erganzt, um besonders den Einfluss des Zinks auf den Ertrag und die Qualitat der Korner aufzufassen. Die Zinkzugabe varierte sich von 0.05 bis 20 v. M. (p.p.m). Die Vegetationszeit dauert 22. IV.-9. IX. 1939. Das Resultat ist folgendes : 1). Die Zinkzugabe von bis lv. M. zeigten einen guten Einfluss auf das Wachstum, den Ertrag und die Qualitat der Korner. Von 5v. M. an ist es schon giftig, 10 v.M. hemmt das Bluhen und 20 v.M. ist recht todlich. 2). Der Zinkgehalt im jeden Pflanzenteilen, wo die giftige Wirkung schon zu bemerken ist, ist folgendes : Wurzel-0.00278%; Stengel-0.0012%; Blatt-0.00076%. 3). Der Kohlenstoffgehalt in Blatt, Stengel und Wurzel variert sich von 39.45% bis 43.79%. Die Beziehung zwischen den Kohlenstoffgehalt und die Zinkzugabe war nicht zu verfolgen. 4). Der Stickstoffgehalt in Blatt, Stengel und Wurzel andert sich etwa in umgekehrter Proportion mit der Zinkzugabe. 5). Das O/N-Verhaltnis ist proportional mit der Zinkzugabe.

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A water culture experiment was made to ascertain the relation between the effects of silica and nitrogen, silica and phosphorus, in the nutrition of rice plant. The result of the experiment can be summarized as follows; (A) In the case of nitrogen and silica. 1. Addition of silica in the culture solution produced great increase in the growth, in the production of grain and straw, in the silica content in the plant. 2. The above effects of silica were observed in all cases of various amount of nitrogen supply, ranging 4 to 70 mg per liter in the nutrient solution, and the greater the amount of nitrogen-supply, the larger were these effects of silica. 3. On the surface of grains grawn in silica-unsupplied plots, numerous brown spots (perhaps a kind of disease) were always observed, and these were greater especially when nitrogen-supply was large, while on the grain in silica-supplied plots the spots were scarcely observed. (B) In the case of phosphorus and silica. 1. The effects of silica described in 1 above were observed in all of cases of various amount of phosphorus-supply, ranging 0 to 50mg per liter, in the nutrient solution, but dislike the case of nitrogen, the increments of yield of grain and straw, decreased with phosphorus supply increased. 2. As to the brown spots, no effect of the amount of phosphorus-supply was observed, 3. In this experiment, it was ascertained that silica plaied the role of phosphorus, even in a very small degree, in the nutrition of rice plant.

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