强降雨下农田径流中溶解态氮磷的输出特征 ——以崂山水库流域为例

在崂山水库流域建立了种植5种代表性作物玉米、大豆、花生、红薯和黄瓜的径流小区,对2009~2010年10次强降雨(大雨或暴雨)产流中溶解态氮磷浓度进行了定位观测,同时记录了降雨基本特征和径流小区各类型作物的种植生长信息.结果显示,5种作物所在径流小区产流中氨氮、硝氮和水溶性磷的事件平均浓度(EMC)均存在较明显的差别,施肥条件和作物类型是造成这种差异的主要原因.玉米、黄瓜所在径流小区产流中溶解态氮磷浓度明显高于其他作物,是由于这两种作物施肥量相对较大,而叶面积指数相对较小.各径流小区的溶解态氮磷流失量与作物叶面积指数存在明显负相关(P<0.05).降雨特征与径流小区溶解态氮磷物质迁移的相关性分析表明,迁移量与次降雨量、小时最大雨强呈现显著正相关(P <0.01).

Characterization of dissolved nitrogen and phosphorus transportation in farmland runoff under heavy rain-take Laoshan Reservoir watershed as example

Runoff plots of five representative crops as corn,soybean,peanut,sweet potato,cucumber were established in watershed of Laoshan Reservoir.Dissolved nitrogen and phosphorus concentrations in the runoff were observed under heavy rain or rainstorm in 2009~2010,and the basic characteristics of rainfall and the information of various types of crops were recorded.The results showed that the event mean concentrations(EMC) of ammonia nitrogen(NH4+-H),nitrate nitrogen(NO3——N) and dissolved phosphorus(DP) were significantly different across the five runoff plots.Crop types and fertilization conditions explained most of the difference.The dissolved nitrogen and phosphorus concentrations in the runoff plots of corn and cucumber were significantly higher than that of other crops,due to the higher amount of fertilization and the smaller leaf area index(LAI) of these two crops.There existed significant negative correlation between dissolved nitrogen and phosphorus losses and crops LAI(P<0.05).The results of correlation analysis between rainfall characteristics and nitrogen and phosphorus transport in the runoff plots showed that the transport load was positively correlated with rainfall and maximum rainfall intensity(P<0.01).