中文摘要：

【目的】研究腐植酸（HA）对土壤氨氧化古菌（AOA）的影响,进而探讨HA对土壤氮循环的作用。【方法】采用末端标记限制性多态性分析（T-RFLP）和实时定量PCR技术,研究了两种腐植酸（原生腐植酸-cHA和降解后的腐植酸-bHA）与尿素一同施加于土壤中的氨氧化古菌（AOA）和古菌的群落结构及数量的变化。【结果】只加尿素的处理AOA数量明显增加,其群落结构也发生明显变化,而加入尿素和两种腐植酸（HA）的处理土壤中,AOA数量增加得到明显的抑制,且典范对应分析（canonical correspondence analysis,CCA）表明尿素是影响AOA群落结构的最大因素,而HA可以缓冲尿素对AOA群落结构的影响,从而可以稳定AOA的群落结构。只加入尿素的处理还导致了古菌数量降低,而两种HA均抑制古菌数量的降低,表明HA可以缓冲尿素对古菌的影响。CCA分析表明时间是影响古菌群落结构的最重要因素,将时间作为共变量的部分典范对应分析（partial canonical correspondence analysis,pCCA）表明除时间外古菌的群落结构对cHA也比较敏感。【结论】这些结果表明HA通过抑制AOA数量而调控其与植物竞争氨来减少氨的损失,从而提高尿素利用率。

英文摘要：

[Objective]To illuminate the impact of humic acid （HA） on soil ammonia oxidizing archaea and then reveal the effect of HA on soil nitrogen cycle. [Methods]Two humic acids （cHA and bHA） were added into the soil amended with urea. Community changes of ammonia oxidizing archaea （ AOA ） and total archaea were studied with terminal restricted fragment length polymorphism （T-RFLP） and real time PCR in the microcosm experiment. [Results]We found that the AOA population size increased significantly and AOA community changed greatly in the urea only treatment. However,HA could inhibit the increase of AOA population,moreover,HA could buffer the change in AOA community showed by canonical correspondence analysis （ CCA） result. On the other hand,the total archaeal population decreased significantly in the urea only treatment,but stabilized in the urea with HA treatments,which indicated HA could eliminate the toxicity of urea to total archaea. CCA results showed that incubation time was the most important factor for the total archaeal community,and partial CCA （ pCCA,when time as a covariable） result demonstrated that cHA was the most important environmental variable for total archaeal community. [Conclusion]These results showed that HA diminished ammonia loss by inhibiting the increase of AOA competing with plant for ammonia,thus HA can increase the urea efficiency.