Our knowledge of the abundance and distribution of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) has substantially expanded over the past decade, but their relative contributions to soil nitrification remain debated, particularly at a global scale. Nitrification inhibitor 1-octyne is the only available selective inhibitor that can exclusively inhibit AOB but not AOA activity, making it a powerful tool to differentiate the functional importance of AOB vs AOA in nitrification. Here, we conducted a meta-analysis of laboratory incubation studies with 1-octyne as the nitrification inhibitor to display a panoramic view of the relative contribution of AOB in soil nitrification across various terrestrial ecosystems. The most pronounced reduction of nitrification rates by 1-octyne was found in cropland (71.4%), followed by grassland (59.6%), forestland (53.2%) and wetland (44.0%), indicating a more dominant role of AOB over AOA in upland soils than in wetland soils. The response ratio of soil nitrification rates with 1-octyne addition to that without 1-octyne addition was negatively correlated to soil pH in upland soils, suggesting that a greater proportion of nitrification was inhibited by 1-octyne with higher soil pH. However, the reduction of nitrification rate by 1-octyne was estimated to be 59.5% in acidic soils (pH ≤ 6.5), indicating a major role of AOB in acidic soil nitrification. The proportion of nitrification rate reduced by 1-octyne was greater in soils incubated in slurry and with nitrogen additions than in microcosm and without nitrogen additions, and this should be taken into consideration during the incubation experiments. Altogether, this meta-analysis provides evidence for an equally or more important role of AOB in nitrification from global acidic soils, advancing our understanding of the microbial nitrification process, which is fundamental to the sustainable management of nitrogen in soils.

在过去十年中，我们对氨氧化古菌 (AOA) 和氨氧化细菌 (AOB) 的丰度和分布的了解已经大大扩展，但它们对土壤硝化作用的相对贡献仍然存在争议，尤其是在全球范围内。硝化抑制剂 1-辛炔是唯一可以专门抑制 AOB 而不能抑制 AOA 活性的选择性抑制剂，使其成为区分 AOB 与 AOA 在硝化中的功能重要性的有力工具。在这里，我们用 1-辛炔作为硝化抑制剂对实验室孵化研究进行了荟萃分析，以展示 AOB 在各种陆地生态系统土壤硝化中的相对贡献的全景图。在农田中发现 1-辛炔对硝化率的降低最显着 (71.4%)，其次是草地 (59.6%)、林地 (53.2%) 和湿地 (44.0%)，表明 AOB 比 AOA 在旱地土壤中的主导作用比在湿地土壤中更显着。添加1-辛炔与未添加1-辛炔的土壤硝化速率的响应比与旱地土壤的土壤pH呈负相关，表明较高比例的1-辛炔抑制硝化作用的比例较高。然而，在酸性土壤 (pH ≤ 6.5) 中，1-辛炔对硝化率的降低估计为 59.5%，表明 AOB 在酸性土壤硝化中起主要作用。1-辛炔降低硝化率的比例在泥浆和氮添加的土壤中比在微观和不添加氮的土壤中更大，这应该在孵化实验中考虑。总而言之，