Nitrogen Loss in the Farmland Surface Runoff under the Natural Rainfall Conditions

In the present study,we studied the characteristics of nitrogen loss in the slope farmland surface runoff under the natural rainfall conditions through the standard runoff plots and micro-plot methods in the Jianshan River Basin in Chengjiang county.The results showed that the quantity and intensity of rainfall were the main factors causing surface runoff.Therefore,some precaution measures should be done in rainy seasons.The maximum nitrogen concentration in surface runoff reached to 30.72mg/L.Nitrate-nitrogen occupied l4%～28%of total nitrogen loss,whereas ammonia-nitrogen accounts only 1%～8%of total nitrogen loss.In conclusion,the accumulative total nitrogen loss in surface runoff was 0.45～1.18kg/hm2,and the loss coefficient was only 0.1%～0.12%.