深蓄控排条件下稻田土壤水氮变化规律

Variation in Paddy Soil Nitrogen as Impacted by Combination of Deep Rainfall Storage and Controlled Drainage

【目的】阐明不同水分管理模式下土壤水氮素的赋存规律。【方法】在肥东灌溉实验站开展试验,观测L1处理(间歇时间3~4 d,蓄雨深度10 cm)、深蓄控排L2处理(间歇时间6~8 d,蓄雨深度14 cm)和L3处理(间歇时间6~8 d,蓄雨深度18 cm)地下埋深50、70、90、110、150 cm土壤水及稻田排水的氮素变化,分析干湿交替L1处理和深蓄控排L2、L3处理的灌水量、排水量以及水稻产量要素的响应规律。【结果】干湿交替灌溉L1处理和深蓄控排模式L2、L3处理较CK水稻灌溉水量分别降低725、1 703、2 304 m^(3)/hm^(2),雨水利用率分别提高11.8%、19.0%、25.9%,稻田排水次数减少1~3次。NH_(4)^(+)-N、NO_(3)^(-)-N和TN随土层深度增加而降低,深蓄控排L2、L3处理总氮峰值低于CK。L1、L2、L3处理TN污染负荷较CK减少21.3%、26.7%、31.5%。各处理间产量差异不显著。【结论】通过增加蓄雨上限至18 cm,延长间歇时间6~8 d,能够有效地减少灌溉定额,降低稻田排水量,提高雨水利用率,达到水稻节水、减排、控污、稳产的目的。

【Objective】Nitrogen in paddy soil is modulated by both rainfall and drainage,and in this paper we present the results of an experimental studies on its response to controlled drainage and deep rainfall storage.【Method】The experiment was conducted in 2018 in field plots at the Feidong Irrigation Experimental Station.We compared two irrigation methods:alternate dry and wet irrigation (L1),and deep rainfall storage and controlled drainage irrigation (L2 and L3).Business as usual used by local farmers was taken as the control (CK).During the experiment we measured nitrogen changes in soil water and the drainage water at the depths from 50 cm to 150 cm,and analyzed the response of nitrogen dynamics to irrigation amount,drainage amount,as well as rice yield under different water managements.【Result】Compared with CK,L1,L2 and L3 reduced the irrigation water by 725 m^(3)/hm^(2),1 703 m^(3)/hm^(2)and 2 304 m^(3)/hm^(2),and increased the rainwater utilization by 11.8%,19.0%and 25.9%,respectively.In the meantime,they also reduced the irrigation times by 1~3.Soil nitrogen content decreased as the soil depth increased,regardless of treatments.Compared to CK,L2 and L3 reduced the maximum total nitrogen (TN) compared to CK,and L1,L2 and L3 reduced TN pollution load by 21.3%,26.7%,31.5%,while no significant difference in the yield was found between them.【Conclusion】Increasing the upper limit of the rainfall storage and extending the interval,coupled with deep rainfall storage and controlled drainage,can effectively reduce irrigation requirement and drainage times,thereby improving rainwater use efficiency.It also reduced nitrogen pollution and can thus be used as an improved agronomic practice for rice production in paddy field.