Nutrient physiology of rice cultivation by grass mulching without chemical fertilyzers.

此外，我们对不施化肥的水田覆盖草的试验结果表明，与普通化肥耕作的产量相同。然而，这将需要比一般人更多的人力。试图建立一种利用盖草原理的新方法，利用盖草提取液浸没在水田灌溉水中提供养分；将干草料在水田一角一处堆积，用温水浸泡分解，提取后的溶液与灌溉水混合后注入水田。以芦苇（Phragnited communis Trinius）、竹草（Pleiobastus variegatus Makino）和黑麦秸秆（Secale cereale L.）为提取液为原料，进行了试验。芦苇提取液的水稻产量为501 g/ <m^2>，芦苇草覆盖的产量为362 g/ <m^2>。与此相比，施氮量相同的化肥施氮量为416 g/ <m^2>。每kg DW从每种草料中提取的营养元素分别为氮9 ~ 17g、磷约2g、钾14 ~ 35g、钙约3g和二氧化硅7 ~ 16g，但由于土壤在此过程中的吸收和反硝化作用，只能回收总提取营养的三分之一。值得注意的是，从浸没草中提取的溶液似乎促进了水稻对二氧化硅的吸收。吸收量大于给予量清楚地证明了这一点；提取的溶液可能会释放出土壤中含有的有效二氧化硅。

Further our experimental results for grass mulching on paddy fields without chemical fertilyzers have showed the same yields with ordinary caltivation with chemical fertilyzers. However, it was to be necessary more amount of man-power than ordinary one. We attempted to estabilish the new method of utilization of the principle of grass mulching, which supplied nutrients by the extracted solution from mulching grass submerged in irrigated water at paddy fields; dried grass was accumulated on one place in the corner of paddy field in order to decompose by submerged in warm water, after that, the extracted solution was given by mixing with irrigation water into the paddy field.Reed(Phragnited communis Trinius), bamboo grass(Pleiobastus variegatus Makino) and rye straw (Secale cereale L.) were used as materials of the extracted solution, giving to experimental plots. Rice yields were 501 g/ <m^2> with the reed's extracted solution and a plot of grass mulching of the reed yielded 362 g/ <m^2> . Comparing with those plots, chemical fertilyzers plot, giving the same amount of nitrogen to the reed's extracted solution plot, was 416 g/ <m^2> .Amount of extracted nutritional elements from each grass materials per 1 kg DW showed a range 9 - 17g of nitrogen, about 2g of phosphorous, 14 - 35g of potassium, about 3g of calcium and 7 - 16g silica, respectively, however, those amount could recovered only one third amount of total extracted nutrition due to absorption of soil and denitrification in the process.It was remarkable that the extracted solution from submerged grass seemed to be promoted absorption of silica by rice plants. It was clearly proved by the larger amount of absorption than the giving amount; the extracted solution might be released aviable silica contained in the soil.