牛场肥水灌溉对土壤氨氧化微生物的影响

以不同牛场肥水灌溉制度下河北省徐水县梁家营长期定位施肥试验田为研究对象,通过构建氨氧化细菌和氨氧化古菌的amoA 基因克隆文库,利用T-RFLP方法研究了5种施肥处理(CK:不施肥;CF:300 kg N·hm^-2,120 kg P₂O·hm^-2,75 kg K₂O·hm^-2;T4:105 kg N·hm^-2,39 kg P₂O₅·hm^-2;T5:210 kg N·hm^-2,78 kg P₂O₅·hm^-2; T11:317 kg N·hm^-2,117 kg P₂O₅·hm^-2)下土壤中氨氧化细菌及氨氧化古菌的多样性及其群落结构演变。氨氧化细菌T-RFLP结果显示,T5 处理土壤中氨氧化细菌的 Shannon-Wiener指数(H')和 Pielou指数(E)均最高, T11处理最低,表明T5处理增加了土壤中氨氧化细菌的多样性和丰富度,T11处理一定程度上降低了氨氧化细菌的多样性和丰富度。基于amoA基因建立的系统进化树显示,土壤中氨氧化细菌主要属于Nitrosospira 和Nitrosomanas。氨氧化古菌T-RFLP结果显示,T11处理氨氧化古菌Shannon-Wiener指数(H')、Simpson 指数(Ds)和Pielou指数(E)均最高,表明T11处理增加了土壤中氨氧化古菌的多样性和丰富度。氨氧化古菌的系统发育树显示大部分氨氧化古菌amoA序列与 Cluster S 聚为一类,且占主导地位,少数序列为Unclassified-Archaea(未分类古菌)。最大优势菌与来自中国荷斯坦奶牛瘤胃样品的氨氧化古菌Clone属于同种,推测牛场肥水灌溉增加了土壤的氨氧化古菌的群落多样性。

Effects of Cattle Farm Effluent Irrigation on Community Structure and Abundance of Ammonia-Oxidizing Bacteria in Soil

Ammonia-oxidizing bacteria(AOB) and ammonia-oxidizing archaea(AOA) play important roles in the biogeochemical cycle of N element, which is closely related to soil quality, greenhouse gas emissions and NO₃^- leaching. Therefore, diversity and composition of soil AOB and AOA are valuable indicators for soil quality monitoring. In this study, the effects of five fertilization treatments, including control without fertilizers(CK), conventional fertilization(CF 300 kg N·hm^-2) and three irrigation treatments with cattle farm effluent(T4 105 kg N·hm^-2, T5 210 kg N·hm^-2 and T11 317 kg N·hm^-2), on the diversity and composition of AOA and AOB were determined through terminal restriction fragment length polymorphism(T-RFLP) of aomA gene(encoding ammonia monooxygenase). Results showed that the diversity indices, Shannon-Wiener(H') and Pielou(E), of AOB were the highest in the T5 treatment, while they were the lowest in the T11 treatment. Phylogenetic tree analysis indicated that the AOB in the soil mainly belonged to Nitrosospira and Nitrosomanas. However, the indices of Shannon-Wiener(H'), Simpson(Ds) and Pielou(E) of AOA were the highest in the T11 treatment, but the lowest in the CF treatment. AOA aomA gene sequences showed that most sequences of AOA were clustered with Cluster S. The dominant AOB was similar to one species from the rumen of China Holstein cow, which was a clue of community evolution in cattle effluent irrigated farmland. The present results indicate that cattle effluent irrigation could affect the diversity and abundance of soil AOA.