尿素在砖红壤中的淋失特征Ⅱ——NO_3^-—N的淋失

Leaching Characters of NO-N in Latosol After Applying UreaⅡ. Loss of NO -N by Leaching

通过室内大型土柱模拟试验研究了不同尿素施用量与砖红壤中NO3--N的淋失关系。结果表明,各处理渗漏液中20cm处NO-3-N浓度变化趋势相似;60cm处渗漏液中各处理NO-3-N最高浓度值均显著高于对应的20cm处;120cm处渗漏液中各处理NO-3-N浓度在39d前无显著变化,之后迅速上升并且随着施肥量的增加而增大,其最高浓度值与施肥量的关系可用方程y=0.5257x+138.2来表示。从120cm处NO-3-N累计淋失量来看,其累计淋失量与施肥量的关系可以用下式来表示:y=0.478x+204.26;最后对各处理NO3--N累计淋失量Yt(gN)与时间t(d)的关系进行拟合。

The relationship between different quantity of urea fertilizer applied and NO3^--N leaching in latosol was studied by large soil columns containing disturbed soils at laboratory. The results showed that： at the depth of 20 cm layer, the changing tendency of the concentration of NO3^--N in leaching water was similar with different quantity of urea applied. At the depth of 60cm layer, the highest concentration of NO3^--N in leaching water with different treatments was significantly higher than the corresponding ones at the depth of 20 cm layer. In the initial 39 days, the concentration of NO3^--N in leaching water at 120 cm depth layer was not significantly different, then ascended sharply. The more of urea quantity was applied, the higher it grows. The relationship between the highest concentration of NO3^--N and fertilizer quantity applied can be shown in the regression equation у=0.525 7х＋138.2; According to the leaching amount accumulated at the depth of 120 cm layer, the relationship between the leaching amount of NO3^--N accumulated and fertilizer quantity applied can be expressed as regression equation у=0.478х＋204.26. Finally, using equation to model the relationship between the accumulation leaching amounts of NO3^--N and times.