不同作物对坡耕地地表径流及氮素流失的影响

Effect of Crop Kinds on Runoff and Nitrogen Losses of Slope Farmland

为了揭示坡耕地种植作物后径流和氮素流失间的差异,采用径流小区法对坡耕地种植玉米、莜麦和土豆3种作物后坡面径流、地面作物状况、氮素流失量及其关系进行了研究。结果表明:2014年7—9月6场侵蚀性降雨平均降雨量为31.49mm,径流量(Q)为Q_(莜麦-总)>Q_(土豆-总)>Q_(玉米-总),且与降雨量成线性关系;作物种类对径流中氮素浓度有显著影响,各形态氮浓度均值范围分别为:NO_3^-—N含量10.33~11.83mg/L,TN含量27.48~31.28mg/L,NH_4^+—N含量0.72~0.92mg/L,NO_2^-—N含量0.35~0.49mg/L;6次侵蚀性降雨全氮流失量(TNL)为TNL_(莜麦)>TNL_(土豆)>TNL_(玉米),均值分别为147.01,139.45,125.63mg;硝态氮流失量(NL_硝)占TNL的33.33%~43.14%,NL_硝和TNL与径流量之间存在线性关系;7—9月份,农作物进入生殖生长阶段,作物覆盖度变化较小,与降雨量和氮素流失量之间没有显著关系,不是影响坡面径流和养分流失的主要影响因素。

In order to reveal the differences of runoff and nitrogen loss in slope farmland,the runoff plots were used to study the slope runoff,crop condition,amounts of nitrogen loss and their relationship on the slope farmland which were planted with corn,naked oats and potato.The results showed that：The mean for6 erosive rainfalls from July to September in 2014 was 31.49 mm.Runoff（Q）followed the order of Qnaked oats-T〉 Qpotato-T〉 Q（corn-T）,presenting a linear relationship with rainfall amount.Crop species had a significant impact on the concentration of nitrogen in runoff.The average values of various forms of nitrogen concentrations were described respectively as：NO3^--N（10.33-11.83mg/L）,TN（27.48-31.28mg/L）,NH4~＋-N（0.72-0.92mg/L）,and NO2^--N（0.35-0.49mg/L）.The total nitrogen loss（TNL）of 6erosive rainfalls under different crop species followed the order of TNLnaked oats〉TNLpotato〉TNLcorn,and the mean values were respectively 147.01 mg,139.45 mg and 125.63 mg.Nitrogen loss of NO3^--N occupied by 33.33%to 43.14% of TNL,and nitrogen loss of NO3^-- N and TNL respectively had a linear relationship with runoff amount.Crop began the reproductive growth from July to September,with a tiny change of crop coverage.Crop coverage had no significant relationship with runoff and nitrogen loss,and was not the main factor that affected the runoff and nutrient loss.