Effects of Different Nitrogen Application Levels on Nitrogen Leaching in Tea Garden Soil

To improve strongly-acidified soil quality of tea garden,a laboratory simulation test of column-leach was carried out to investigate the effects of applying different nitrogen rates on the pH,ammonium nitrogen(NH+4-N)and nitrate nitrogen(NO-3-N)of soil leachate.With urea as nitrogen fertilizer,the different applications were respectively treated with N0(0kg·hm-2),N1(150kg·hm-2),N2(300kg·hm-2),N3(450kg·hm-2)and N4(600kg·km-2).The results showed that the pH values of soil leachate were be decreased by 0.08~0.32and0.35~0.81 with different N application rates,resulting in more soil acidification.The leaching amounts of NH+4-N and NO-3-N were increased by increasing rates of nitrogen fertilizer,and 47.66%~71.31%inorganic nitrogen was lost in leaching water.The regression equation between inorganic nitrogen loss(Y)and N application rates(X)was Y = 0.708 X +145.27(R2=0.98).The leaching of NH+4-N and NO-3-N majorly occurred at the first five times,and the leaching amounts of NO-3-N accounted for 73.50%~89.21% of the total leaching inorganic nitrogen.