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| Soil N2O emission pathways，microbial mechanisms and targeted regulation in dryland farmland：a review |
| Received:November 15, 2024 |
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| KeyWord:dryland farmland;N2O emission pathways;microbial mechanism;targeted regulation;nitrification inhibitors |
| Author Name | Affiliation | | LI Shiqing | College of Resources and Environmental Science, Gansu Agricultural University, Lanzhou 730070, China | | HE Renyuan | College of Resources and Environmental Science, Gansu Agricultural University, Lanzhou 730070, China | | GAO Na | Carbon Neutrality Research Center, Shijiazhuang University, Shijiazhuang 050035, China | | LUO Zhuzhu | College of Resources and Environmental Science, Gansu Agricultural University, Lanzhou 730070, China |
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| Abstract: |
| Farmland soils are a major source of N2O emissions in terrestrial ecosystems. Dryland soils contribute around 50% of global N2O emissions from farmland. The pattern of N2O emissions in dryland farmland soil is unique, exhibiting a phenomenon known as "wetting or nitrogen application pulse".Based on our long-term research, this review systematically examines the pathways and microbial mechanisms involved in N2O production in dryland farmland soils, discusses potential regulatory pathways for inhibiting N2O production, and evaluates the effectiveness of nitrification inhibitors in reducing N2O emissions from farmland soils and the prospect of the industrial production of nitrogenous fertilizer containing nitrification inhibitors. Specifically, ammonia oxidation pathways that use ammonium（NH4+）as the substrate—such as autotrophic nitrification, denitrification by nitrifying bacteria, nitrification-coupled denitrification—are the primary sources of N2O emissions. The contribution of complete ammonia-oxidizing microorganisms（comammox） to N2O emissions in the autotrophic nitrification should not be overlooked. Inhibiting ammonia oxidation pathways driven by ammonia-oxidizing bacteria, which use NH+4 as the substrate, may represent a key strategy for regulating N2O emissions in dryland farmland.Furthermore, this review discusses future research directions for understanding N2O emissions in dryland farmland. Future studies should integrate multiple methods, such as isotope tracing and molecular biology techniques, and employ multi-scale field experiments that distinguish between rhizosphere and nonrhizosphere emissions. Additionally, research should consider various factors, including different farmland management practices, to comprehensively elucidate the pathways and mechanisms of N2O emissions in dryland soils and to understand the heterogeneity of emissions between the rhizosphere and non-rhizosphere environments. Moreover, future research should focus on identifying suitable nitrification inhibitors for N2O mitigation in dryland soils, developing a theoretical framework for N2O emissions in dryland farmland, and proposing key targeted regulatory pathways for N2O reduction. |
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