水田氮素径流-侧渗-下渗流失特征模拟

基于水氮耦合平衡理论和田间实际观测,开发了一套既简单又综合的水田氮素流失特征模拟模型.模型模拟结果表明：氮转化速率常数经率定后能够准确表征水田尿素氮施入后在径流、侧渗和下渗等途径上的流失速率变化特征;同时由于氮素径流流失受自然环境干扰较大,其模拟准确度较低于下渗和侧渗.对黄斑土水田,在各个途径上单季累积模拟流失通量与田间观测结果较为吻合,误差均在20%以下,其中侧渗和下渗的误差小于10%.因此,可认为模型能对水田氮素多个途径的流失速率及通量进行有效模拟.

Modeling of nitrogen losses via runoff, vertical leach and lateral seepage from urea applied rice field

On the basis of water-nitrogen coupling balance theory and field observation results, a simple but comprehensive model was developed to predict nitrogen losses from a urea applied rice paddy field, considering all the important hydrological pathways such as surface runoff, lateral seepage, and vertical leaching. Predicted results show that the model could accurately reflect the characteristics of nitrogen exports by above three pathways in a urea applied rice field after the identifications of various nitrogen transformation rate constants. The predicting accuracy of nitrogen loss by surface runoff is lower than lateral seepage and vertical leaching because of disturbance of nature rainfall. However, the errors of nitrogen losses between predicted and observed results are all less than 20% in three hydrological pathways, especially in vertical leaching and lateral seepage which are less than 10%.