氮添加对东祁连山高寒草甸土壤养分及地上生产力的影响

Effects of nitrogen addition on soil nutrients and above-ground productivity in alpine meadow of east Qilian Mountains

摘要:

为探讨氮添加对退化高寒草甸土壤养分和地上生产力的影响，以祁连山东段高寒草甸草原为研究对象，在样地内分别施入 0，10，20，30，40 g/m² 的尿素，测定不同施氮水平下地上生产力和不同土层土壤养分含量。结果表明：随着施氮量增加，地上生产力呈现升高趋势，施氮量在 40 g/m² 下达到最大值 194 g/m² ；但过高的施氮量不能显著增加地上生产力，在施氮量大于 30 g/m² 之后，地上生产力增加不显著；随着施氮量增加，0~20 cm 土层土壤全氮和有机质含量降低，在施氮量 40 g/m² 时最低，相比未施氮分别降低了 19. 95% 和 14. 04%；在 0~20，20~40，40~60 cm 土层，铵态氮含量呈现先升高后降低的趋势，在 20 g/m² 尿素下达到最大值；4 个土层中，硝态氮的含量均呈现升高的趋势，在 30 g/m² 尿素水平下达到最大值；在各个土层中，速效磷含量整体呈现随土层深度增加先升高后降低的趋势，施氮量与土壤全磷，全钾和速效钾之间均没有显著相关性。

Abstract:

In order to explore the effects of nitrogen application on soil nutrients and above -ground productivity of degraded alpine meadow，this study took the alpine meadow in the eastern section of Qilian Mountains as the re- search object，and applied 0，10，20，30，40 g/m² urea to measure above-ground productivity and soil nutrient content in different soil layers under different nitrogen application levels. The results showed that the aboveground productiv- ity increased with the increase of nitrogen application rate，but too low or too high nitrogen application rate did not sig- nificantly increase aboveground productivity. With the increase of nitrogen application rate，the contents of soil total nitrogen and organic matter decreased；however the contents of ammonium nitrogen，nitrate nitrogen and available phosphorus increased significantly. There was no significant correlation between N application rate and soil total P，to- tal K and available K. In this area，the optimal amount of nitrogen application was 30 g/m² .