不同暗管布置下棉田排水的硝态氮流失量分析

为了研究不同暗管控制水深、暗管间距和暗管埋深条件下暗管排水中硝态氮流失量的变化规律,将暗管控制水深、暗管间距和暗管埋深的变化范围分别设为30～80cm、8～40m和80～120cm,采用通用旋转组合设计确定试验方案,并利用DRAINMOD模型对不同试验方案下暗管排水中硝态氮的流失量进行数值模拟。模拟结果表明:单一增加暗管出口控制水深或暗管埋深以及单一减小暗管间距都会使暗管排水中硝态氮流失量增加。暗管间距和暗管埋深对暗管排水中硝态氮流失量的影响要比暗管出口控制水深的影响大,当暗管出口控制水深小于40cm时,暗管埋深对其影响大于暗管间距;而当暗管出口控制水深大于70cm时,暗管间距对其影响大于暗管埋深。当暗管埋深不变时,增大暗管间距的同时减小暗管出口控制水深有助于减小暗管排水中的硝态氮流失量。

Analysis of nitrate-nitrogen loss under different underground pipe layout

In order to simulate the law of nitrogen loss under different weir depths, drainage spaces and drainage depths in underground pipes, field experiment was conducted and nitrogen loss was simulated by DRAINMOD 6.0. The ranges for three factors were set to be 30-80 cm, 8-40m, and 80-120 cm respectively, and the values of three experimental parameters in each simulation were determined with the method of General Rotation Design. The results indicated that the amount of nitrogen loss in drainage tended to be larger as the weir depth or the drainage depth increased, or the drainage space decreased alone. The effects of drainage space and drainage depth on nitrogen loss were greater than those of weir depth. The weir depth was less than 40 cm, drainage depth had greater influence on nitrogen loss than drainage space, and there was an opposite result when the weir depth was deeper than 70 cm. If the drainage depth was the same, the effective way to reduce the nitrogen loss in drainage was to expand the drainage space and decrease the weir depth at the same time.