Ammonia-oxidizing bacteria (AOB) and archaea (AOA) are very important in regulating the process of soil nitrification. However, little is known how responses of AOB and AOA communities to yak excreta application in wetland soils. We investigated AOB and AOA community composition using excreta application treatments to examine how nitrification response to yak excreta application by regulating the ammonia-oxidizing microorganism communities in meadow marsh soil (MMS) and marsh soil (MS). The microcosm experiments of excreta application were established in MMS and MS. The microcosms were subject to dung application (DA), urine application (UA) and control (CK). Molecular methods were applied to determine the compositions of AOA and AOB. Chao, ACE, Shannon and Simpson indices were applied to measure species richness and diversity. Potential nitrification rate (PNR) was higher in MMS than in MS. DA significantly increased PNR in MMS, whereas DA decreased PNR in MS. The urease activity was lower in MMS than in MS, whereas catalase activity was opposite. DA increased urease and catalase activities significantly in MMS and MS. Excreta application decreased the alpha diversity of AOB in MMS whereas the trend was opposite in MS, and it was higher in MMS than in MS. The canonical correspondence analysis (CCA) demonstrated that the urease and catalase activities were the important factors to change the AOB community structure in MS. Structural equation modelling (SEM) showed PNR was indirectly influenced by total phosphorus (TP) through mediation of the ACE index and Simpson index of AOB. Yak excreta application can alter soil environmental conditions resulted in changes in AOB community composition. However, the response of AOA to yak excreta application was much weaker than that of AOB in both MMS and MS.

氨氧化细菌（AOB）和古细菌（AOA）在调节土壤硝化过程中非常重要。然而，AOB 和 AOA 群落对牦牛排泄物在湿地土壤中的应用的反应知之甚少。我们使用排泄物应用处理研究了 AOB 和 AOA 群落组成，以通过调节草甸沼泽土壤 (MMS) 和沼泽土壤 (MS) 中的氨氧化微生物群落来研究硝化作用对牦牛排泄物应用的反应。在MMS和MS中建立了排泄物应用的微观实验。微观世界受到粪便施用（DA）、尿液施用（UA）和对照（CK）的影响。应用分子方法测定AOA和AOB的组成。Chao、ACE、Shannon 和 Simpson 指数用于衡量物种丰富度和多样性。MMS 中的潜在硝化率 (PNR) 高于 MS。DA 显着增加 MMS 中的 PNR，而 DA 降低 MS 中的 PNR。MMS中脲酶活性低于MS，而过氧化氢酶活性相反。DA 显着增加 MMS 和 MS 中的脲酶和过氧化氢酶活性。排泄物的应用降低了MMS中AOB的α多样性，而MS中的趋势相反，MMS中高于MS。典型对应分析（CCA）表明脲酶和过氧化氢酶活性是改变 MS 中 AOB 群落结构的重要因素。结构方程模型 (SEM) 显示 PNR 通过 AOB 的 ACE 指数和辛普森指数的中介而受到总磷 (TP) 的间接影响。牦牛排泄物的施用可以改变土壤环境条件，导致AOB群落组成发生变化。然而，在 MMS 和 MS 中，AOA 对牦牛排泄物的响应比 AOB 弱得多。