减少氮流失的田间地表控制排水措施研究

针对南方丘陵地区地表排水方式，通过设计和使用自动开启闸门、土工布沙袋和捆扎秸秆作为排水口控制措施，控制降雨初期氮浓度较高的地表水流出农田。通过田间排水试验，研究自动开启闸门、土工布沙袋、捆扎秸秆控制和非控制排水中氮浓度的变化规律，分析了 3种控制排水措施减少农田氮流失的机理和氮浓度随时间的变化。对比非控制排水，3种控制排水措施分别减少了53.2％、44％和39.1％的农田氮流失。以控制排水氮浓度和土壤入渗为目标函数，建立了既减少氮流失又防止涝渍的多目标控制排水模型，探讨了最优的地表控制排水时间。

Effect of drainage controlling devices on nitrogen losses in surface runoff of farmland

The effect of various drainage control devices on nitrogen in surface runoff of farmland is experimentally studied in Jiangsu Province. The controlling devices at the outlet of open channel drainage system include the self-open strobes, fabric sandbags and packed straws. It is found that all these three types of controlling devices significantly affect the water quality of runoff. They reduce the nitrogen concentration losses by keeping the surface water stay in the farmland for a certain period of time. The nitrogen losses will be reduced by 53.2%, 44% and 39.1% when the self-open strobes, fabric sandbags and packed straws are used respectively. For preventing from harmful water-logging due to impertinent long period detention of surface water, a model for optimizing the management of drainage control based on multi-objective optimization method is proposed, in which concentration of nitrogen in water and infiltration are regarded as the objective functions.