日本土壌肥料学雑誌

To a highly acidic mineral soil of tertiary origin added CaCO_3 in ascending rates of amount and cultivated above named four crops. 1) The wheat grows best on the soil which contains good supply of lime and react neutral or slightly basic. 2) The buckwheat grows best on the soil with moderate supply of lime and react weakly acidic or neutral. But it has fairly good adaptation for the wide range of soil reaction. 3) Though the rye grows best on the soil of weak acidic reaction with moderate supply of exchangeable lime, it can thrive on the soil of very wide range of reaction from highly acidic to basic without much retarding its yield. 4) Though the oat grows best on the soil of weak basic reaction with good supply of lime, it can grow on the fairly strong acid soil with moderate supply of exchangeable lime.

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1) When the constituents of the rice plant which was cultured in the water Solution was analysed, generally the plants, cultured in the Solution with silicic acid, had the more following ingredients in ears than the plant, cultured in the Solution without silicic acid : - ash, silicic acid, phosphoric acid, sulphuric acid, potash, ferric oxide, and magnesia 2) In the water culture, we should add silicic acid from 0.6 to 3mg. in the 1 litre culture Solution in order to raise rice completely. 3) There was intimate relation between the quantities of manuring of phosphoric acid and silicic acid which might be useful for the growing of rice and barley plants. 4) The growth of the barley plants which were cultured in the water solution without silicic acid, were worse than that of the plants which grew in the Solution with silicic acid. Note. 1. The culture solution of this experiment was follows : [table] Note 2. Water solution was exchanged every 1 to 5 days. Note 3. The volume of the celluloid pot was about 1 litre.

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In the previous paper, a method for collecting the soil samples under the natural state was described in detail. This Paper deals with the results obtained in the laboratory by using the soil samples collected by the said procedure, regarding the influence of temperature on the microorganisms as well as the rate of temperature change in the monolith itself after placed in the incubator and also the change of pH values. Five soil samples in all, two from unmanured and one from manured rice-field, and two from dry-farm, were taken and placed in an incubator at 28℃. The results are summarised as follows : 1.) It required 26-31 hours to reach 28℃ from 5℃-14℃ which were the original temperature. 2.) The pH values of rice-field soils became somewhat smaller while no change was observed with the dry-farm soils. 3.) The maximum number of bacteria was reached after 84 hours of incubation in the case of rice-field soils while it took only 60 hours with the dry-farm soils. However no marked difference was noted among the samples as to the ratio of increase. 4.) The change of fungous number showed the similar tendency as the bacteria.

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The fertilizer ratio, which is understand as the ratio existing between the percentage of nitrogen, phosphorus and potash in a fertilizer is a most important factor in manuring practice, as it determines the efficiency of the fertilizer used. The growth of plant being affected by the condition of soil and climate, the fertilizer ratio suitable for a plant is not the same everywhere the plant is cultivated. The determining factors of this ratio of a fertilizer seem, therefore, to be the following : 1) Kind of crop. 2) Climatic conditions. 3) Soil character. It is, then, desi able to find a fundamental relation of these factors to the fertilizer ratio in the form of an equation, as we have not heretofore known anything about the deduction of such an equation. As the first step of an investigation the writers intended to study the relation of temperature to that ratio in the fertilizer given to wheat plant. And the result obtained was published in This Journal Vol IX No. 3 (1935). The Present report, as the second, embodies the result dealed with the rice Plant. Calculating out the ratios of P_2O_5 and K_2O to N respectively from the amounts of the ingredients in a manure generally used by farmers, in 261 districts in Japan from north to south, an examination was made of their relation to the annual mean temperature and also the accumulated temperature thronghout the growth period in each district. The following equation in the case of P_2O_5 to N was found to denote clearly the relation existing between the ratio and temperature. [numerical formula] where Tm : mean annual temperature Ts : accumulated temperature throughout the growth period. This indicates that the ratio of P_2O_5 to N is high at the districts of low temperature, decreasing linearly as the temperature increases regardless of the annual temperature or the accumulated temperature. In the case of K_2O to N, the following equation was obtained : [numerical formula] This represents also that the same tendency of temperatucr relation to the ratio as in the case of P_2O_5 to N can be seen even in the case of K_2O to N.

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