三峡库区王家沟小流域不同坡度土壤氮素流失特征研究

Nitrogen Loss Characteristics of Wangjiagou Small Watershed with Different Slopes in the Three Gorges Reservoir Region

采用野外径流小区观测方法,研究了三峡库区王家沟小流域旱坡地不同坡度土壤氮素的流失特征。结果表明:①旱坡地不同坡度小区土壤氮素流失量总体不大,单场降雨侵蚀泥沙氮素流失量最大值为189.06 mg/m2,而在地表径流中仅为28.12 mg/m2,侵蚀泥沙氮素流失量明显高于地表径流氮素流失量,最大差异达到16.8倍,差值随着坡度的增大有减少的趋势;坡度越大,地表径流氮素和侵蚀泥沙氮素的流失量也越大,呈现出小区17°>9°>4°的趋势;铵态氮流失量明显低于硝态氮流失量,4°、9°、17°小区地表径流硝态氮流失量较铵态氮流失量分别高出3.2、3.6、4.0倍,说明硝态氮较铵态氮更易于流失,且随着坡度的增大差异增大。②不同坡度小区地表径流量、侵蚀泥沙流失量与降雨量均存在显著的线性正相关(P<0.05),且随着坡度的增大地表径流量与降雨量的相关系数在增大,侵蚀泥沙流失量表现则相反,这可能与土壤母质、作物生长等情况有关。

The paper studied the characteristics of soil nitrogen loss of arid sloping land with different slopes of Wangjiagou small watershed in the Three Gorges Reservoir area by using the method of field runoff plots observation. The outcomes show that a) the soil nitrogen loss of arid sloping land with different slopes is not great in general. The maximum value of eroded sediment nitrogen loss in one event of rainfall is 189. 06 mg / m2,only 28. 12 mg/m2in surface runoff. The eroded sediment nitrogen loss is obviously higher than that of the surface runoff and the maximum difference is 16. 8 times. There is a trend that the difference is decreased along with the increase of slope. The greater the slope is,the greater the nitrogen loss of surface runoff and eroded sediment will be,showing the trend of 17 ° > 9 ° > 4 °. The ammonium nitrogen loss is obviously lower than that of nitrate nitrogen loss. The nitrate nitrogen loss of surface runoff in 4 °,9 ° and 17 ° plots are 3. 2 times,3. 6 times and 4 times respectively higher than that of the ammonium nitrogen loss,showing that the nitrate nitrogen loss is more easily than that of ammonium nitrogen and the difference is increased along with the increase of slope. b) The surface runoff,eroded sediment loss and rainfall of plots with different slopes all have significant linear positive correlation( P < 0. 05). The correlation coefficient of surface discharge and rainfall is increased along with the increase of slope and the eroded sediment loss is just the opposite,which may be related to the conditions of parent soil material and crop growth.