施肥方式对干旱半干旱地区土壤氨氧化微生物数量和群落的影响

氨氧化是硝化作用的限速步骤，也是评估土壤氮循环和提高氮肥利用效率的重要指标。以内蒙古农牧业科学院旱作实验站长期定位实验为基础，通过实时荧光定量PCR和末端限制性片段长度多态性分析，研究了5种施肥方式（单施氮肥、单施有机肥、氮磷钾配施、有机无机配施和不施肥）对土壤氨氧化古菌（AOA）和氨氧化细菌（AOB）群落丰度、结构和活性的影响。结果表明：单施氮肥、氮磷钾肥配施以及有机无机肥配施均能显著提高AOB的丰度以及土壤硝化潜势。Nitrosospiria cluster 3a.1是不施肥土壤中主要的AOB种群，而施用氮肥后优势种群转变为Nitrosospiria cluster 3a.2。Nitrosospiria cluster 3b的比例在施用有机肥处理土壤中显著升高。在干旱半干旱地区，土壤pH和含水量是解释AOB群落结构变化的关键环境因子。AOA的丰度在单独施用氮肥处理中显著升高，但不同施肥方式对AOA的群落结构没有显著影响。

Effects of long-term different fertilization regimes on the abundance and community structure of ammonia oxidizers in semi-arid ecosystem

Ammonia oxidation is a rate-limiting step of nitrification and an important index to evaluate nitrogen cycling in soil. Real-time PCR, terminal restriction fragment length polymorphism and clone library analysis were used to investigate the effects of long-term different fertilization regimes on the abundance and community structure of ammonia oxidizers in a long-term localization experiment in the dry farming station of the Inner Mongolia Academy of Agricultural and Animal Husbandry Sciences. Five treatments were compared including chemical nitrogen (N) fertilization, chemical nitrogen, phosphorous and Potassium fertilization (NPK), manure only (O), NPK plus manure (NPK+O), and no fertilizer as control. The results showed that the abundance of ammonia-oxidizing bacteria (AOB) and nitrification potential were significantly increased in N, NPK, and NPK+O treatments. The sequences of AOB in the control soil were mostly affiliated with genus Nitrosospira clusters 3a.1. The soil treated with N increased the abundance of AOB that belonged to Nitrosospira clusters 3a.2. In contrast, the O-treated soil showed more abundant AOB that belonged to Nitrosospira clusters 3b. In the semi-arid ecosystem, the soil pH and soil moisture were identified as the dominant drivers of the AOB community structure. The abundance of ammonia-oxidizing archaea (AOA) was only increased by applying of urea, while different fertilizations did not have significant effect on the AOA community structure.