氮沉降对西藏高山灌丛草甸土壤理化性质的短期影响

氮沉降已经成为全球性的环境问题,为了更好地了解氮沉降对高山灌丛草甸土壤理化学性质的影响,2014年7月,在西藏林芝县布久乡朱曲登村开展人工模拟氮沉降试验,设置4种氮沉降量:对照(CK),0 kg·hm~2·a~(-1);低氮(LN),25 kg·hm~2·a~(-1);中氮(MN),50 kg·hm~2·a~(-1);高氮(HN),150 kg·hm~2·a~(-1)。以NH4NO3作为氮源,每月以溶液方式对草地进行喷施,在模拟氮沉降1年后,采集0~20 cm和20~40 cm土层的土壤,探讨了氮沉降对土壤理化性质的影响。结果表明:不同程度模拟氮沉降对草地有机质、全N、全P、全K、速效N、速效P、速效K、交换性Ca2+、交换性Mg2+的含量以及可溶性有机碳的含量都有显著影响(P0.05)。在相同处理下,有机质、全N、速效N、速效P、速效K、交换性Ca2+和可溶性有机碳含量均随土层的加深而减少,全P和全K含量随土层的加深而增加。总体上,氮处理显著增加了20~40 cm土壤的有机质、N、P、K、交换性Ca2+和可溶性有机碳的含量,对0~20cm土壤的影响较小。

Short-term Effects of Nitrogen Deposition on Soil Physical and Chemical Properties of Alpine Shrub Meadow in Tibet

Nitrogen deposition has become a global environmental problem.In order to better understand the effect of nitrogen deposition on soil physical and chemical properties of alpine shrub meadow, four deposition contents of artificial simulated nitrogen were carried out in July 2014 in Zhuqu Deng village:0 kg ·hm2 · a-1(CK), 25kg· hm2 · a-1(LN), 50kg· hm2 · a-1(MN), and 150kg· hm2 · a-1(HN), respectively.NH4NO3was used as nitrogen source and sprayed every month.After 1 year of simulated nitrogen deposition, the effect of nitrogen deposition on soil physical and chemical properties in 0～20 cm and 20～40 cm soil layer was discussed.The results showed that the simulated nitrogen deposition had a significant effect on the contents of organic matter, total N, total P, total K, available N, available P, available K,exchangeable Ca2+, exchangeable Mg2+ and soluble organic carbon (P ＜0.05).Under the same treatment, the contents of organic matter, total N, available N, available P, available K, exchangeable Ca2+ and soluble organic carbon decreased with the increase of soil depth.Total P and K increased with the increase of soil layer.In general, nitrogen treatment significantly increased the contents of organic matter,N, P, K, exchangeable Ca2+ and soluble organic carbon of 20 ～ 40 cm soil, but had little effect on 0～20 cm soil layer.