习惯施肥对菜地氮磷径流流失的影响

对菜地进行连续3年的定位监测试验。结果表明:与不施肥对照相比,菜农习惯施肥处理显著提高降雨径流中的总氮(TN)和硝态氮(NO3--N)流失质量浓度及流失量,3年监测期内总氮(TN)径流流失负荷为321kg/hm2,总磷(TP)流失负荷为134kg/hm2,分别占氮、磷养分投入总量的13.6%和13.2%,氮肥的流失系数约为5.6%。菜地氮素流失以硝态氮(NO3--N)形式为主,磷素流失以颗粒态磷(PP)形式为主。菜地氮、磷养分径流流失与径流量呈显著线性关系,菜地每流失1kg的总磷(TP),可溶性总磷(TDP)、总氮(TN)、硝态氮(NO3--N)、铵态氮(NH4+-N)所需要的径流量分别为77.5,322,52.5,67.5,404m3。

Impacts of Custom Fertilization on N and P Losses by Runoff in Vegetable Fields

A 3-year monitoring experiment located at a vegetable field in Guangzhou,south China was conducted to survey the nitrogen(N) and phosphorus(P) losses by runoff.The results showed that compared with the control(no fertilization),custom fertilization increased significantly the content of total nitrogen(TN) and NO-3-N in the runoff,and the runoff loss quantity of TN,NO-3-N(p<0.05).The loss load of TN was 321 kg/hm2,and that of total phosphorus(TP) was 134 kg/hm2.The runoff losses of TN and TP occupied 13.6% and 13.2% of total application of N and P,respectively,and nitrogen loss coefficient was about 5.6% by runoff during the 3-year experiment.Majority of P and N loss form in runoff was particulate phosphorus(PP) and NO-3-N,respectively.A significant linear correlation was found between N loss(P loss) and surface runoff.When loss quantity of TP,TDP,TN,NO-3-N,NH+4-N in a vegetable plot was 1 kg,that need 77.5,322,52.5,67.5,404 m3 of surface runoff,respectively.