基于DNDC模型的稻田氮素流失及其影响因素研究

稻田氮素流失是导致农业面源污染的主要原因之一。采用测坑定位实验获得的野外观测数据对DNDC模型模拟稻田氮素流失的可行性进行验证,同时重点采用模型的敏感性分析功能对影响稻田氮素流失的关键因素进行分析研究。结果表明:DNDC模型能够准确地模拟不同施肥条件下稻田的氮素流失和水稻产量,施肥和降雨是影响稻田氮素流失的主要因素,与稻田氮素流失呈正比。值得注意的是,在目前施肥水平下有机肥的施用对稻田氮素的渗漏流失无明显贡献。此外,稻田氮素的渗漏流失还与土壤硝态氮的含量呈正比,而与土壤有机碳含量和黏土比例呈反比。根据敏感性分析结果可知,在我国稻田目前的施肥水平下,降低施肥量、采用节水灌溉以及增施有机肥等措施均是减少稻田氮素流失的有效手段。

Modeling N loss from paddy fields and sensitivity analysis with DNDC Model

N loss from paddy fields lead to agricultural non-point source pollution. Observed data from lysimeter study was used for validation of DNDC model, and then sensitivity analysis was conducted with DNDC model to evaluate the impact factors that affect N loss from paddy fields. The results indicated that DNDC model accurately simulated rice yields and N loss from paddy fields under different fertilization methods. Fertilization and precipitation are the major factors that affect N loss from paddy field, and showed positive correlation with N loss. N loss through subsurface leaching negatively correlated with SOC content and soil clay fraction, while positively correlated with soil nitrate content. According to sensitivity analysis, decreasing of fertilization rate, application of water-saving irrigation and organic manure could effectively reduce N loss from paddy fields.