Xi Ruijiao, Long Xi-En, Huang Sha, Yao Huaiying
Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, People's Republic of China.
Ningbo Key Laboratory of Urban Environmental Processes and Pollution Control, Ningbo Urban Environment Observation and Research Station-NUEORS, Chinese Academy of Sciences, Ningbo, 315800, People's Republic of China.
AMB Express. 2017 Dec;7(1):129. doi: 10.1186/s13568-017-0426-x. Epub 2017 Jun 21.
Nitrification inhibitors and urease inhibitors, such as nitrapyrin and N-(n-butyl) thiophosphoric triamide (NBPT), can improve the efficiencies of nitrogen fertilizers in cropland. However, their effects on ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) across different soil pH levels are still unclear. In the present work, vegetable soils at four pH levels were tested to determine the impacts of nitrification and urease inhibitors on the nitrification activities, abundances and diversities of ammonia oxidizers at different pHs by real-time PCR, terminal restriction fragment length polymorphism (T-RFLP) and clone sequence analysis. The analyses of the abundance of ammonia oxidizers and net nitrification rate suggested that AOA was the dominate ammonia oxidizer and the key driver of nitrification in acidic soil. The relationships between pH and ammonia oxidizer abundance indicated that soil pH dominantly controlled the abundance of AOA but not that of AOB. The T-RFLP results suggested that soil pH could significantly affect the AOA and AOB community structure. Nitrapyrin decreased the net nitrification rate and inhibited the abundance of bacterial amoA genes in this vegetable soil, but exhibited no effect on that of the archaeal amoA genes. In contrast, NBPT just lagged the hydrolysis of urea and kept low NH-N levels in the soil at the early stage. It exhibited no or slight effects on the abundance and community structure of ammonia oxidizers. These results indicated that soil pH, rather than the application of urea, nitrapyrin and NBPT, was a critical factor influencing the abundance and community structure of AOA and AOB.
硝化抑制剂和脲酶抑制剂，如硝吡啉和N-（正丁基）硫代磷酸三酰胺（NBPT），可以提高农田中氮肥的效率。然而，它们在不同土壤pH水平下对氨氧化古菌（AOA）和氨氧化细菌（AOB）的影响仍不清楚。在本研究中，对四种pH水平的菜园土壤进行了测试，通过实时荧光定量PCR、末端限制性片段长度多态性（T-RFLP）和克隆序列分析，来确定硝化抑制剂和脲酶抑制剂对不同pH值下氨氧化菌的硝化活性、丰度和多样性的影响。对氨氧化菌丰度和净硝化速率的分析表明，AOA是酸性土壤中主要的氨氧化菌和硝化作用的关键驱动因素。pH值与氨氧化菌丰度之间的关系表明，土壤pH主要控制AOA的丰度，而不是AOB的丰度。T-RFLP结果表明，土壤pH能显著影响AOA和AOB的群落结构。硝吡啉降低了该菜园土壤的净硝化速率，并抑制了细菌amoA基因的丰度，但对古菌amoA基因的丰度没有影响。相比之下，NBPT只是延缓了尿素的水解，并在早期使土壤中的NH-N水平保持在较低水平。它对氨氧化菌的丰度和群落结构没有或只有轻微影响。这些结果表明，影响AOA和AOB丰度和群落结构的关键因素是土壤pH，而不是尿素、硝吡啉和NBPT的施用。
