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Abstract：
Synthetic inhibitors and organic amendment have been proposed for mitigating greenhouse gas N2O emissions. However, their combined effect on the N2O emissions and ammonia-oxidizer (ammonia-oxidizing bacteria and archaea, AOB and AOA) communities remains unclear in calcareous soils under climate warming. We conducted two incubation experiments (25 and 35 °C) to examine how N2O emissions and AOA and AOB communities responded to organic amendment (urea plus cattle manure, UCM), and in combination with urease (N-(n-butyl) thiophosphoric triamide, NBPT) and nitrification inhibitor (nitrapyrin). The treatments of UCM + nitrapyrin and UCM + nitrapyrin + NBPT significantly lowered total N2O emissions by average 64.5 and 71.05% at 25 and 35 °C, respectively, compared with UCM treatment. AOB gene abundance and α-diversity (Chao1 and Shannon indices) were significantly increased by the application of urea and manure (P < 0.05). However, relative to UCM treatment, nitrapyrin addition treatments decreased AOB gene abundance and Chao 1 index by average 115.4 and 30.4% at 25 and 35 °C, respectively. PCA analysis showed that UCM or UCM plus nitrapyrin notably shifted AOB structure at both temperatures. However, fertilization had little effects on AOA community (P > 0.05). Potential nitrification rate (PNR) was greatly decreased by nitrapyrin addition, and PNR significantly positively correlated with AOB gene abundance (P = 0.0179 at 25 °C and P = 0.0029 at 35 °C) rather than AOA (P > 0.05). Structural equation model analysis showed that temperature directly increased AOA abundance but decrease AOB abundance, while fertilization indirectly influenced AOB community by altering soil NH4+, pH and SOC. In conclusion, the combined application of organic amendment, NBPT and nitrapyrin significantly lowered N2O emissions via reducing AOB community in calcareous soil even at high temperature. Our findings provide a solid theoretical basis in mitigating N2O emissions from calcareous soil under climate warming.
摘要：
已经提出了合成抑制剂和有机改良剂来减轻温室气体N2O的排放。然而,它们对N2O排放和氨氧化剂(氨氧化细菌和古细菌，在气候变暖的情况下，钙质土壤中的AOB和AOA）群落仍不清楚。我们进行了两个孵化实验（25和35°C），以检查N2O排放以及AOA和AOB社区对有机改良剂（尿素加牛粪，UCM),并与脲酶（N-（正丁基）硫代磷酰三胺，NBPT)和硝化抑制剂(硝普林)。在25和35°C下，UCM三氯甲基吡啶和UCM三氯甲基吡啶NBPT的处理显着降低了总N2O排放平均64.5和71.05％，分别,与UCM治疗相比。施用尿素和粪肥显著提高了AOB基因丰度和α-多样性(Chao1和Shannon指数)(P<0.05)。然而,相对于UCM治疗，在25和35°C下，硝普林添加处理使AOB基因丰度和Chao1指数平均降低了115.4％和30.4％，分别。PCA分析表明，在两个温度下，UCM或UCM加硝普林都显着改变了AOB结构。然而,施肥对AOA群落影响不大(P>0.05)。潜在的硝化速率（PNR）是通过添加硝普林，大大降低，PNR与AOB基因丰度呈显著正相关(25°C时P=0.0179,35°C时P=0.0029),而非AOA(P>0.05)。结构方程模型分析表明，温度直接增加AOA丰度，但降低AOB丰度，而施肥通过改变土壤NH4+间接影响AOB群落，pH和SOC。总之,有机修正案的联合应用，即使在高温下，NBPT和硝普林也可以通过减少石灰性土壤中的AOB群落来显着降低N2O的排放。我们的发现为减轻气候变暖下钙质土壤中N2O的排放提供了坚实的理论基础。
