On Purification Ability of Soil Layr of Paddy Field with Underdrain

本研究的目的是阐明水稻种植季节利用地下排水对稻田土壤层的净化能力。所以，考试的方法是1)场，2)罐，3)列。现场检查是在试验场入口和出口连续测量水量和水质，渗透速率为7mm/天。用1/2000a瓦格纳锅进行盆栽试验的典型结果是：以2 ~ 40mm /d的渗滤速率，1 ~ 10mg /l的灌溉水中，T-N和NH_4^+的去除率为70 ~ 99%。在高污染条件下，水稻植株的效果显著。采用直径为5cm的土柱，改变NH_4^+的密度和渗滤速率，进行柱状检测。23种检查方式的结果也很多样化。但用一个比密度-渗流修正孔隙体积方程可以解释所有的结果。有大孔的土柱比无大孔的土柱吸收氮量少。通过三种类型的实验，阐明了土层对污染水体具有净化作用。为了保证其效果，必须对土壤和水进行管理。

The purpose of this study is to clarify purification ability of soil layr of paddy field using underdrain during rice planting season. So, the method of examination is 1) Field, 2) Pot and 3) Column.Field examination is the continuous measurement of water volume and quality at the inlet and outlet of the test field with percolation rate of 7mm/day. The quality was analyzed at NO_3^-, NH_4^+, COD, Fe Mn, etc.The typical result of pot examination with 1/2000a Wagner pot is that 70-99% of T-N and NH_4^+ was removed from irrigation water of 1-10 mg/l at the percolation rate of 2-40 mm/d. And the effect of rice plant was eminent at high contamination.Column examination was executed with soil column of 5cm diameter, changing density of NH_4^+ and percolation rate. The results of 23 patterns of examination were also diversified. But one equation of specific density with percolation modified pore volume can explain all of the results.Soil column with macropore can absorb less nitrogen than that without macropore.From three types of experiments, it was clarified that soil layr can purify contaminated water. To ensure its effect properly, soil and water management is necessary.