田块尺度上土壤/地下水中硝态氮动态变化特征及模拟

以青岛市大沽河下游地区冬小麦–夏玉米轮作农田为对象,通过田间试验和室内分析,研究了不同深度土壤和地下水中NO3–-N在一个轮作周期内的动态变化特征,探讨了不同氮肥施用量和灌溉量对土壤-地下水系统中NO3–-N时空分布的影响,并基于土壤水动力学和溶质运移理论对土壤中NO3–-N运移过程进行了数值模拟。模拟结果表明:小麦季施氮(N)量达到380 kg/hm2,玉米季施氮量达到290 kg/hm2时,季末剖面深度130~160 cm土壤NO3–-N含量超过10 mg/kg;由地下水NO3–-N月累计量估算模型得出,NO3–-N在6月和8月向浅部地下水的淋失量最大,分别为7.20、7.67 mg/L。

Dynamic Characteristic and Numerical Simulation of Nitrate Nitrogen in Soil-Groundwater System at Field Scale

During the last two decades,soil nitrate nitrogen leaching and even groundwater contamination due to surfeit use of excessive fertilizer in agricultural production activities has been a central subject people pay close attention to. Taking the farmland of Qingdao Dagu river downstream in which summer corn and winter wheat is planted as an example in this article, we revealed the dynamic characteristics of nitrate nitrogen from soil at different depths and groundwater in the rotation period through field experiment and lab analysis. The impact of fertilization and irrigation on nitrate in soil and ground water was canvassed and numerical simulation of nitrate pollution process in soil and groundwater based on the theory of soil water dynamics and solute transport is carried out. Nitrate content will exceed 10 mg/kg in depth of 160 cm at the end of the season, when the nitrogen rates reach 380 kg/hm2 in wheat season and 290 kg/hm2 in corn season. A monthly cumulative model of nitrate in groundwater is established, Results showed that month cumulant of groundwater nitrate is largest in June and August and the results are 7.20 mg/L and 7.67 mg/L respectively.