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

此外，我们在不施化肥的稻田上进行的草覆盖试验结果表明，与普通化肥覆盖的产量相同。然而，这需要比普通人力更多的人力。我们试图建立一种利用覆草原理的新的利用方法，即利用稻田灌溉水中覆草提取液提供养分，将干草堆积在稻田角落的一个地方，浸泡在温水中分解，然后将提取液与灌溉水混合供应到稻田中。以提取液为原料，配以试验田。芦苇提取液水稻产量为501g/lt；m^2；芦草覆盖小区产量为362g/lt；m^2。与这些小区相比，施氮量相同的化肥小区芦苇浸提液施氮量为416g/lt；m2；gt；每公斤干重中每种牧草的浸提液营养元素含量分别为9-17g氮，约2g磷，14-35g钾，约3g钙和7-16g二氧化硅，但由于土壤的吸收和反硝化作用，这些量只能回收总浸出量的三分之一。值得注意的是，沉水草浸提液似乎促进了水稻对二氧化硅的吸收。吸附的量大于给药量清楚地证明了这一点；提取的溶液可能是土壤中含有的可释放的二氧化硅。

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.