氮沉降对杉木林土壤有效氮和磷含量的影响

为探究长期氮沉降对土壤有效氮和磷含量的影响，以亚热带杉木人工林为研究对象，研究10 a 氮沉降对杉木人工林土壤有效氮、磷含量的影响，并探讨干、湿季土壤有效氮、磷含量对氮沉降的响应动态。试验分为对照(0 kg?hm－2?a－1)、低氮(60 kg?hm－2?a－1)、中氮(120 kg?hm－2?a－1)、高氮(240 kg?hm－2?a－1)4种处理模拟氮沉降试验，结果表明，随着施氮量的增加，土壤铵态氮、硝态氮和有效氮含量呈上升趋势，并且铵态氮和硝态氮表现出明显的季节动态。土壤pH值和NH＋4－N/NO－3－N值随着施氮量增加而降低，有效磷的含量在中氮处理中最高， N/P值均在一个较高的水平范围。

Impacts of nitrogen deposition on soil available N and P contents in the Chinese fir plantation

In order to examine the effects of long-termed nitrogen deposition on soil available N and P content, the subtropical Chinese fir plantation was taken as a research object, the experiment included four treatments, N0 ( 0 kg?hm-2?a-1 ) , N1 ( 60 kg?hm-2?a-1 ) , N2( 120 kg?hm-2?a-1 ) , N3( 240 kg?hm-2?a-1 ) to investigate the responses of soil available N and P contents to the N deposition in the dry and wet seasons. The results indicated that the contents of soil ammonium nitrogen, nitrate nitrogen and available nitrogen showed obvious seasonal dynamics and were enhanced along with the nitrogen level, while soil pH and NH+4-N/NO3-- N had a decreasing tendency. The content of available P was the highest in the middle nitrogen treatment N2 ( 120 kg?hm-2?a-1 ) . In this experiment, the ratio of N and P was at a high level.