用DrainMOD模型模拟稻田排水与氮素流失

稻田排水伴随的氮素流失是造成当前农业面源污染的主要原因之一。DrainMOD排水模型和DrainMOD-N氮素运移模型是模拟田间尺度下土壤水氮运移的有效工具。该文将模型应用于湿润的水稻种植区，对湖北漳河灌区稻田排水和氮素流失过程进行了模拟。结果显示，水稻全生育期模拟排水总量、硝态氮和铵态氮流失总量与实测值吻合较好，相对误差分别为4.6%、16%和2.8%，但从各生育阶段分开的模拟结果来看，还存在较大的误差。经初步分析，观测资料有限，模型参数率定不充分是主要原因。研究总体表明，DrainMOD模型可以有效地描述稻田排水排氮过程，对提高水肥效率，预防面源污染具有重要意义。

Simulation of drainage process and nitrogen loss in paddy field using DrainMOD

Excessive nitrogen loss in drainage of paddy field is a main contributor of agricultural non-point source pollution (NPS). DrainMOD and DrainMOD-N are well-performed models to simulate farm drainage and nitrogen loss at a field scale. By applying this model in humid rice-growing areas, drainage process and nitrogen loss in experimental areas of Zhanghe Irrigation District, Hubei Province were simulated. Results showed that there was a good agreement between simulated and observed values of total drainage, nitrate nitrogen loss and ammonium nitrogen loss, with the relative errors of 4.6%, 16% and 2.8% (relative error of nitrate nitrogen was a little bigger), respectively. However, in terms of the different growing stages of paddy rice, there was large deviation between simulated and observed values. Preliminary analysis indicated that the parameters used in the model were not calibrated well due to limited observed data. On the whole, DrainMOD model can efficiently describe and predict drainage and nitrogen loss processes in paddy field, which plays an important role in improving efficiency of water and nitrogen use in farmland as well as reducing agricultural pollution.