暗管控制排水对棉田排水的影响

对几次较大规模降雨产生排水后排水量、排水氮素含量、地下水位等进行观测,结果发现暗管排水使得地表、地下排水量被重新分配,控制水位排水使地表排水量所占比例提高、而总排水量比常规排水减少36.4%～82.7%、地下排水峰值量较常规排水减少7.2%～85.4%。地表、地下排水硝氮质量浓度较低,一般低于4 mg/L;地表排水总氮质量浓度在2.3～11.5 mg/L之间,地下排水总氮质量浓度在0.6～9.1 mg/L之间。要减少氮素流失总量,减少排水量是关键。

Effect of Controlled Pipe Drainage on the Drainage in Cotton Field

A field experiment was conducted in Drainage and Irrigation Station in Yajiao,Jingzhou,Hubei Sihu district during the growth period of cotton in 2008.The study tracked three heavy rains which resulted in drainage and compared the treatments of different drainage water tables.Drainage outflow,nitrogen concentration and water table were observed.Three rainfalls occurred in the rainy season and the precipitations and drain outflow were large.Results showed that surface and subsurface drain outflow were relocated by controlled drainage,and the surface drainage ratio was improved.Total drain outflow was reduced by 36.4%~82.7% through controlled drainage.The nitrogen concentration in the drainage from the cotton field was low and the nitrite nitrogen concentration was lower than 4 mg/L.The key to reduce nitrogen leaching was to reduce drain outflow.