中文摘要：

以中国科学院红壤生态试验站发育于第四纪红黏土的植稻红壤为研究对象，研究了长期种植水稻和施用无机肥对土壤8．变形杆菌纲中氨氧化细菌多样性和硝化作用的影响。原始红壤改种水稻13年后，氨氧化细菌16SrDNA的DGGE条带数量增加，条带谱与原始红壤的差异较大，相似性为61％，说明种植水稻后土壤氨氧化细菌群落结构发生了变化。PCR-DGGE方法研究结果也显示，长期施用无机氮肥的处理（NP、NPK和NK），DGGE带谱相似性较高，达到73％，硝化率和硝化势均高于未施用氮肥的处理。逐步回归分析显示硝化率和硝化势均随着土壤脲酶活性的提高而显著增加。推测尿素可提高土壤水解氮含量，使土壤脲酶活性提高，促进硝化细菌的生长，进而提高硝化率和硝化势。

英文摘要：

Effects of rice-planting and long-term application of inorganic fertilizers on 13-proteobacteria ammonium oxidizers diversity and nitrification were investigated in a soil derived from quaternary red clay in the Ecological Experimental Station of Red Soil, Chinese Academy of Sciences. The original soil is characterized by low pH and deficiency of available nutrients, particularly phosphorus and nitrogen. After 13 years of rice cultivation, the soil showed increase in number of DGGE bands of ammonium oxidizer 16S rDNA and a DGGE pattern different from that of the original soil with a similarity being only 61%, which illustrated variation in the community structure of the ammonium oxidizers in the soil. Besides, the research findings of the experiment on effect of long-term application of inorganic fertilizers on diversity of ammonium oxidizers in the soil with the PCRDGGE method also showed that the treatments （NP, NPK ＆ NK） in the experiment were quite similar to each other in 16S rDNA DGGE pattern, with a similarity being up to 73 %. Both nitrification rate and nitrification potential were higher in the nitrogen fertilizer treatments than the other treatments. Stepwise regression analysis showed that nitrification rate and nitrification potential were evidently increased with the increase in urease activity. It may be presumed that application of urea increased soil hydrolysable nitrogen content, and hence urease activity and growth of nitrifying bacteria in the soil, which finally led to increase in nitrification rate and nitrification potential.