模拟降雨条件下不同种植方式的坡地氮素流失特征

Nitrogen Loss of Slope Cropland Under Different Cropping Patterns and Rainfall Simulation Conditions

以花生（PL）、玉米（CL）、玉米和花生套种（TCP）3种种植方式下的坡耕地为研究对象,通过人工模拟降雨方法,研究不同种植方式下坡面的产流产沙过程及氮素流失特征,并以裸地（BL）作为对照。结果表明：PL、CL、TCP和BL的地表径流量大小依次为BL〉CL〉PL〉TCP,雨强为1.20mm/min时,其产流量分别为195.6L,182.1L,23.4L,11.9L,以BL的产流量为基准,TCP,PL和CL分别减少地表径流的比例为94%,88%和7%。不同种植方式下产沙量的排列次序为BL〉CL〉PL〉TCP,其产沙量分别为947g,72g,19g,4g,以BL的产沙量为基准,TCP,PL和CL减少泥沙的比例分别为99.6%,98.0%,92.4%;地表径流中的总氮、硝态氮、铵态氮浓度变化特征表明：除TCP外,PL、CL、BL在产流结束前地表径流中总氮、硝态氮、铵态氮浓度基本达到稳定状态,径流中氮素流失的主要形式为硝态氮,占总氮流失的比例为54%～79%。不同种植方式下的氮素流失量表现为TCP,

In this paper,we selected slope croplands under 3cropping patterns,including peanut monoculture（PL）,corn monoculture（CL）,and corn and peanut intercropping（TCP）,as research objects to explore the runoff and sediment yield,as well as nitrogen loss,on slope cropland under simulated rainfall conditions.The bare land（BL）was selected as control.The results showed that the surface runoff amount on slope cropland under different cropping patterns listed in the order of BL〉CL〉PL〉TCP.When the rainfall intensity was 1.20mm/min,the runoff amount of slope croplands of BL,CL,PL and TCP were 195.6L,182.1L,23.4Land 11.9L,respectively.Compared to BL,TCP,PL and CL reduced runoff amount by 94%,88%and 7%,respectively.The sediment yield under different cropping pattern followed the sequence of BL〉CL〉PL〉TCP.The sediment yields of slope croplands of BL,CL,PL and TCP were 947 g,72g,19 g and 4g,respectively,and compared to BL,TCP,PL and CL reduced sediment yield by 99.6%,98.0%,92.4%,respectively.Concentration variations of total nitrogen,nitrate nitrogen and ammonium nitrogen in surface runoff indicated that the nutrient concentration in surface runoff reached a stable value in slope croplands of PL,CL and BL before the end of runoff yielding.Nitrate nitrogen was the main form of runoff nitrogen loss,which accounted for 54%~79% of total nitrogen loss amount.The total nitrogen loss amount in the sediment（STN）gradually decreased and then tended to be stable during runoff process.The nitrogen loss amount under different cropping patterns followed the order of TCP〈PL〈CL〈BL.Sediment nitrogen losslisted in the order of TCPPL CLBL,which were 4mg,23.4mg,80.5mg and 937.1mg,respectively.In general,nitrate nitrogen in runoff was the main form of nitrogen loss.