稻田水肥管理对不同尺度区域农业面源污染排放规律影响分析

Effects of Irrigation and Fertilization in Paddy Field on Discharge of Agricultural Non-point-source Pollution in Different-scale Districts

采用SWAT数学模型来模拟稻田水肥管理制度对不同尺度区域农业面源污染排放规律,可为制订科学的农业面源污染防治技术措施提供依据。通过在江西省赣抚平原灌区选取封闭小流域——芳溪湖小流域,进行不同尺度区域农业面源污染排放规律分析模拟,结果表明:节水灌溉模式间歇灌溉较当地传统淹水灌溉模式对削减氮、磷排放负荷具有明显优势;同时,农业面源污染田间尺度较流域尺度削减作用更大,表明从源头改善田间灌溉模式,将起到更好的减污效果。随着施氮肥量的减少及施肥次数的增加,稻田尺度和流域尺度总氮排放负荷均相应减少,但总磷排放负荷变化均很小;随着施磷肥量的减少,稻田尺度和流域尺度总磷排放负荷均相应减少,但总氮排放负荷变化均很小。

In order to provide the basis for drawing up a scientific prevention technique measure of agricultural non-point- source pollution, this study used SWAT mathematic model to simulate and analyze the effects of different paddy field irrigation and fertilization systems on the discharge law of agricultural non-point-source pollution in different-scale districts in the Fangxi Lake basin, which is located in the Ganfu Plain Irrigation Area of Jiangxi Province. The results showed that the intermittent irrigation, a kind of water-saving irrigation mode, presented obvious advantages in the reduction of nitrogen and phosphorous discharge load as compared with the traditional flooding irrigation mode. In addition, the agricuhural non-point-source pollution reduction effect was better in the field scale than in the basin scale, indicating that the pollution would be decreased more if the field irrigation mode was improved in the source of pollution. When the nitrogen fertilizer application rate decreased and the fertilization times in- creased, the discharge load of total nitrogen decreased in both the field scale and the basin scale, but the change in discharge load of total phosphorous was very small. When the phosphorous fertilizer application rate decreased, the discharge load of total phos- phorous decreased at two different scales, but the change in discharge load of total nitrogen was very small.