暗管控制排水棉田氮素流失规律试验

Experimental study of nitrogen leaching pattern in controlled pipe-drainage cotton field

为了研究不同排水出口埋深条件下田间氮素流失规律,2008年在湖北荆州丫角排灌试验站棉田进行暗管控制排水对照试验。结果发现,控制排水条件下,地表氮素累积流失量较暗管多。暗管排水量随控制排水出口埋深减小而减少,较自由暗管排水减少61.3%～86.9%。暗管排水氮素累积流失量主要受排水量影响。NH4+_N累积流失量随排水出口埋深减小而减少;当出口埋深为30cm时由于浓度增加,NO-3-N、TN累积流失量在两次降雨后较50cm处理和80cm处理增加。暗管排水出口埋深控制在30～50cm之间有利于减少排水量和氮素累积流失量。

In order to study nitrogen leaching patterns in cotton field under different drainage treatments,a field pipe controlled drainage experiment was conducted at Yajiao Drainage and Irrigation Experimental Station,Jingzhou City,Hubei Province,in 2008.Results showed that under controlled drainage,accumulation of nitrogen loss from surface drainage was larger than that from pipe drainage.Pipe drain outflow reduced by 61.3%-86.9% as the depth of the outlet declined.Nitrogen loss of pipe drainage was mainly influenced by drain outflow.Ammonia nitrogen loss reduced with rising of the drainage outlet depth.Due to increment of the nitrogen concentration,nitrate and total nitrogen loss of 30 cm treatment were larger than that of 50 cm and 80 cm treatments.Depth of drainage outlet was suggested to be between 30 cm and 50 cm,which could reduce both drain outflow and nitrogen loss.