模拟降雨条件下坡度对茶园红壤氮素流失影响

Impacts of Slope on Nitrogen Losses from Red Soil in Tea Garden Under Simulated Rainfall

以新安江流域茶园红壤为研究对象,采用人工模拟降雨方法,研究其在五种不同坡度(0°、5°、10°、15°、20°)下的产流和氮素流失的特征。结果显示,径流以壤中流为主,地表径流中的氮素在流失过程中表现出了很强的初期冲刷效应,壤中流的氮素流失量随着降雨的持续而逐渐增大;在各种坡度下,氮素均以壤中流流失为主;地表径流中总氮、硝态氮、氨氮的流失量y与坡度x的回归方程分别为y=1.03e0.06x-0.88(R2=0.99**)、y=0.37e0.06x-0.36(R2=0.98**)、y=0.002x+0.004(R2=0.94**),壤中流中总氮、硝态氮、氨氮的流失量y与坡度x的回归方程分别为y=-5.65e0.06x+30.49(R2=0.91**)、y=-0.17e0.16x+14.92(R2=0.98*)、y=0.77e-0.18x+0.13(R2=0.92*)。随着坡度的增大,地表径流中氮素的流失呈增大趋势,壤中流中氮素的流失呈下降趋势。

Slope plays important roles in nutrient losses from soils, especially under rainfall. A laboratory simulated rainfall experiment was conducted to investigate the characteristics of runoff and nitrogen losses from red soil in tea garden in Xin＇ anjiang River Basin under five slope gradients of 0°, 5°, 10°, 15° and 20°. Results showed that runoff occurred mainly as interflow. Nitrogen losses in surface runoff had initial flush effect after each raining event, whereas those in the interflow increased with raining time. Under all slope gradients, nitrogen losses were mainly through interflow. For the surface runoff, regression equation for nitrogen losses（y） and slopes（x） was y=1.03e^0.06x-0.88 with Re=0.99＊＊ for total nitrogen, y=0.37e^0.06x-0.36 with R2=0.98＊＊ for NO3--N, and y=0.002x＋0.004 with R2=0.94＊＊ for NH4＋-N. For the interflow, that was y=-5.65e^0.06x＋30.49 with R2=0.91＊＊ for total N, y=-0.17e^0.16x＋ 14.92 with R2=0.98＊ for NO3--N, and y=0.77e^-0.18x＋0.13 with R2= 0.92＊ for NH4＋-N. These equations indicated that with increasing slopes nitrogen losses increased in the surface runoff, but decreased in the interflow.