中文摘要：

选取盐城市射阳县典型圩区作为苏北平原河网地区的代表性区域，通过2a的野外观测试验研究径流小区尺度（60m2）种植棉花、油菜、玉米和大豆等不同旱作作物农田和田块尺度（10hm2）的地表径流磷素流失特征。结果表明，2009和2010年秋熟作物棉田径流小区地表径流总磷负荷分别为356．60和290．28g·hm-2。2010年玉米和大豆径流小区地表径流总磷负荷分别为169．08和192．20g·hm-2。2010年春熟作物油菜径流小区地表径流总磷负荷为128．74g·hm-2。研究期间共观测到11次田块尺度的降雨产流事件，次降雨事件地表径流总磷负荷平均值为50．66g·hm-2，次降雨事件地表径流总磷的EMC平均值为0．23mg·L-1。田块尺度地表径流总磷负荷平均值和EMC平均值均高于径流小区尺度。降雨、农田耕作管理措施和农田沟渠分布是平原河网区农田地表径流磷素流失的主要影响因子。

英文摘要：

Phosphorus loss from the farmland at the surface runoff plot scale （60 m2） and the field scale （10 hm2） with surface runoff was investigated in a plain river network region typical of North Jiangsu Province through two years of field observation. The fields were cultivated with upland crops, like cotton, rape, maize, and soybean crops, separately. Results show that the total phosphorus load in surface runoff from the plot cultivated with cotton was 356. 60 and 290. 28 g ·hm-2 in 2009 and 2010, respectively, higher than those from the plots cultivated separately with maize, soybean and rapeseed, that is, 169.08, 192. 20 and 128.74 g ·hm-2, respectively, in 2010. During the two years of field observation, a total of 11 field-scaled rain-triggered runoff events were observed. Of the 11 events, the average total phosphorus load in surface runoff was 50. 66 g·hm-2 and the mean concentration of total phosphorus in surface runoff was 0. 23 mg·L-1. They were higher from fields than from plots. Rainfall, farmland cultivation and management practices, irrigation-drainage ditch distribution were the main factors affecting phosphorus loss with surface runoff in the plain river network region.