An Investigation of the Effect of Controlled Drainage Management (in Soil Setting of Rice Husk Envelope) on the Drain Water's Content of Nitrate in Situations Similar to Paddy Rice Fields

On paddy rice fields, as practiced in the case of the use of nutrients or chemical fertilizers is indispensable for high yields. The use of chemical fertilizers in paddy rice fields together with their being leached through either irrigation, or rain water leads to ground water pollution. Optimum design and management of drainage systems including the reuse of controlled drainage water play an important role in reducing slots as well as other contaminants in the drain water. Throughout the present study, the effect of controlled drainage with an application of rice husk envelopes on the quantity of drain water’s nitrate and nitrite (in similar conditions prevailing on paddy rice fields) was investigated. Controlled drainage together with rice husk envelope of 10cm thickness, installed at 40cm of soil depth was scrutinized within the scope of the physical model. The effects of two fertilizer treatments at two levels of 10 and 20 mgr/l as well as drainage management at three levels of: opening the drain to reach saturation, field capacity or 50% saturation, on drain water’s nitrate, nitrite and acidity parameters were investigated. The results revealed that the 50% saturation management together with a concentration of 10 mgr/l of fertilizer presented the most acceptable performance in reducing the drain water’s nitrate (12.08 mgr/l). Also the treatments of field capacity moisture at a concentration of 10 mgr/l of fertilizer and 50% saturation moisture at a concentration of 20 mgr/l of fertilizer respectively led to the highest vas lowest nitrate seepages through the drain water. With a lapse of time, the drain water’s acidity shifted to a normal.