稻田控制排水对减少氮磷损失的影响

地面排水是稻田氮磷损失的重要途径。击溅侵蚀、排水沟坡面和沟底冲刷导致农田氮磷进入地表径流。控制排水可减少地面排水量和排水中氮磷浓度,尤其是降低径流中氮磷浓度,从而减少稻田氮磷损失。土壤颗粒沉淀、硝化、反硝化反应以及作物吸收是排水中氮磷浓度降低的主要原因。通过控制涝水在稻田和排水沟中的滞留时间,增加排水沟口溢流堰高度,降低径流水力坡度和挟沙能力是控制排水的主要手段。最后提出了稻田控制排水需要进一步研究的问题。

Effect of Controlled Drainage on Loss of Nitrogen and Phosphorous from Paddy Field

Surface drainage is a very important way that nitrogen(N) and phosphorous(P) lost from paddy field. Splash erosion and loss of topsoil from slope and bottom of farm furrows resulted in the loss of N and P. Controlled Drainage could reduced the amount of surface drainage and concentration of N and P in runoff, especially concentration of N and P in runoff, caused the reduction of loss of N and P from paddy field. Deposition of soil grains, decline of concentration of particulate N and P in water absorption by plants as well as nitrification and denitrification were the major reasons for the reduction of N and P in water both in filed and furrows. Controlled drainage could be conducted by controlling drainage time from field and furrow, increasing elevation of spillway, decreasing hydraulic slope of runoff and sediment-carrying capacity. Issues need to be further investigated were also suggested in the end.