泥炭地稲作に関する研究(第1報) : 泥炭地水田に於ける水稲の生育相並びに養分吸収の特異性

抄録

In Japan, as a whole, peat lands are mostly used as paddy field for rice culture. It is also the same in Hokkaido so long as the climatic conditions permit the growth of rice plant as in the case of Ishikari district. The yield of rice from that type of land is high if the weather is favourable, while it is very low in the cold year compared with the yield of ordinary mineral soils. In order to make clear the reason, writers undertook to make a comparison of the metabolism of rice plants grown in peat soil with those grown in mineral soils, as well as to study the edaphological characteristics of peat soil. The following conclusions were reached : 1) After flowering poriod when the demand of rice plant for nitrogen becomes low, the decomposition of peat occurs and liberates soluble nitrogen. In the case of a cold year, that period is delayed until later causing a disturbance in the normal metabolism of rice plant as occurs also in case of delayed top-dressing of ammonia. 2) Peat soils in Ishikari district are low in potassium content, and, moreover, that content decreases markedly at the flowering stage of rice plant. So, rice plant becomes deficient in potassium just when the plant needs it remarkablly. 3) The volume weight of peat soil is very low. Especially it becomes low in paddy field condition, because methan-gas is produced as the result of decomposition of peat. So, the rice plants contact comparatively small amounts of nutrients in the soil surrounding their root.