The Research Of Reducing Agricutural Nitrate Losses Implementing Controlled Drainage In Ning Xia Yin Nan Irrigating Region

This paper, based on reviewing amount of research results on controlled drainage, designing the experimental methods establishing the field plot experiment in Xi Wei 2 team Yong Ning Wang Yuang town of Ning Xia Yin Nan irrigating region ,the main experimental items are : the changes of water table in groundwater ,the drainage amounts in ditch ,the changes of the nitrate amounts in groundwater, the changes of the ammoniacal nitrogen in groundwater , the changes of the nitrate and ammoniacal nitrogen in ditch. The results are as follows:1. Implementing controlled drainage in Yin Nan irrigating region is feasible , it also can make some saving water resource and environmental benfit.2. The ditch of implementing controlled drainage can reduce outflows average by 34% than implementing no controlled drainage in same situation (the ditch long 296 m , the drainage area 35 a unit area ), the ditch 2 and theditch 3 are two ditches of implementing controlled drainage in this experiment, the drainage volume in turn are 264.43m3 and 433.39m3 in type period , the average a unit area drainage volume are 7.57 m3and 12.38 m3.in all, the drainage volume of a unit area average is 9.98m3 under implementing controlled drainage situation.3. The values of the nitrate concentration of groundwater (different depth) is bigger in May and June . The values of the nitrate concentration keep stable and small situation after July .This situation is similar with the values of the nitrate concentration in the ditch, the reason is that the farmer fertilize much more in May and June , but the farmer can not fertilize after 20 June . So this is why that the value of the nitrate concentration is small in groundwater and ditch after July.4. The value of the groundwater ammoniacal nitrogen is stable and no big changes except several days, generally almost values of the ammoniacal nitrogen are low 2 mg/L. The value of the ammoniacal nitrogen in ditch is low 1 mg/L.5. Under controlled drainage situation , 1 ha rice field, can reduce average 13.53 kg nitrate in all growing period of the rice .