残膜量对膜孔灌土壤水氮运移特性的影响

为探究土壤残膜量对膜孔灌肥液入渗土壤水氮运移特性的影响,通过室内土箱模拟试验设置0,90,180,360,720 kg/hm~2的5个残膜量水平,分析不同残膜量下膜孔灌肥液入渗累积入渗量、湿润锋运移距离、湿润体特征和水氮分布规律。结果表明:残膜对膜孔灌肥液入渗具有阻渗作用,残膜土累积入渗量较无残膜土减少10.63%～30.77%,Kostiakov模型对残膜土单位膜孔面积累积入渗量与入渗时间有较好地拟合效果;入渗前30 min,不同残膜量的垂直湿润锋运移距离差异不显著,随着入渗时间推进,残膜量与湿润锋运移距离、湿润体体积呈负相关关系。入渗结束时,含残膜土湿润体体积减小18.09%～41.96%。垂直湿润锋距离、湿润体体积与入渗时间均呈显著的幂函数关系,R~2均0.98;除膜孔中心处,相同位置含残膜的土壤含水率低于无残膜,30%高含水率区域减小。湿润体内同一深度土壤NO_3~--N和NH_4~+-N含量随残膜量增加而减小,减小幅度为4.20%～16.27%。研究结果可为残膜土下膜孔灌技术提供理论参考。

Effects of Residual Plastic Film on Characteristics of Water and Nitrogen Transport Under Film Hole Irrigation

In order to explore the influence of the amount of soil residual plastic film on the water and nitrogen transport characteristics of the infiltration of film hole irrigation, five residual plastic film levels were set up through an indoor simulation test, which were 0, 90, 180, 360 and 720 kg/hm², respectively. The cumulative infiltration volume, the wetting front migration distance, the characteristics of the wetted body, the distribution of water and nitrogen were studied. The results showed that the residual plastic film had a negative effect on the infiltration of film hole fertilizer solution, and the cumulative infiltration of the residual plastic film soil reduced by 10.63%~30.77% compared with the without residual plastic film soil. The Kostiakov model matched well with the cumulative infiltration per unit pore area of the residual plastic film soil and the infiltration time. Concretely, the vertical wetting front migration distance of different soil residual plastic film amount did not change significantly for initial 30 min, while, the amount of residual plastic film was negatively correlated with the wetting front migration distance and the wetted body volume with time. When the infiltration was completed, the wetted body volume decreased by 18.09%~41.96%. The vertical wetting front migration distance and wetted body volume had significant power function relationship with infiltration time with R²>0.98; the soil water content with residual plastic film at the same position was lower than that without residual plastic film except for the center of the film hole, and the area with high water content of 30% decreased. The content of NO₃^--N and NH₄⁺-N in the soil at the same depth in the wetted body decreased with increasing residual plastic film, and the range was 4.20%~16.27%. The research can provide theoretical reference for the application of film hole irrigation technology in residual plastic film area.