灌排调控的稻田排水中氮素浓度变化规律

Variation of nitrogen concentration in drainage water from paddy fields under controlled irrigation and drainage

基于农田排水氮素浓度及湿地进出口断面总氮(TN)、氨态氮(NH4+-N)、硝态氮(NO3--N)浓度的监测,研究了灌溉排水措施以及沟塘湿地对农田排水中氮素浓度变化的影响。结果表明,控制灌溉的水稻全生育期稻田排水中TN、NH4+-N和NO3--N浓度分别较常规灌溉处理低12.08%、20.33%和13.51%;控制排水处理下稻田排水中TN、NH4+-N和NO3--N浓度分别较常规排水处理低2.21%、7.08%和20.92%;湿地出口水体中TN、NH4+-N和NO3--N浓度分别比入口降低了16.8%、14.4%和50.9%,湿地水体中TN、NH4+-N、NO3--N浓度随时间近似服从指数函数衰减趋势。控制灌溉、控制排水及沟渠塘湿地系统的调控措施对农田排水中氮素的净化效果比较显著。

Taking ditch-pond wetland system into account,with two treatments,namely controlled irrigation drainage and conventional shallow-wetting irrigation with no drainage regulation,nitrogen concentrations in drainage water from paddy fields were monitored and the variations of nitrogen concentrations were investigated.The results showed that comparing with conventional shallow-wetting irrigation during the whole growth period of rice,total nitrogen（TN）,NO3-N,NH4 ＋-N concentrations under controlled irrigation were reduced by 12.08%, 20.33% and 13.51%, respectively;comparing with conventional drainage, TN, NH4＋-N and NO3-N concentrations under controlled drainage was reduced by 2.21%, 7.08% and 20.92%, respectively. TN, NH4＋-N and NO3--N concentrations from inlet to outlet of the wetland were lowered by 16.8%, 14.4% and 50.9%, respectively. TN, NHa＋-N, NO3-N concentrations in the wetland attenuated exponentially with time. Overall, the measures of controlled irrigation, controlled drainage and the ditch-pond wetland system are effective in removing nitrogen in drainage water from paddy fields.