Recent progress in microbial production and consumption of nitrous oxide in agricultural soils

Agricultural soil is a significant source of nitrous oxide (N2O), a long-lived greenhouse gas. Several microbial processes in the nitrogen cycle generate N2O but the only known sink for N2O in the biosphere is the reduction of N2O to N-2 catalyzed by N2O reductase (NosZ). In this review, we summarized the latest knowledge on (i) key microbial pathways regulating N2O production and consumption processes in agricultural soils, including nitrification and denitrification and (ii) emerging strategies for microbial-mediated mitigation of N2O emissions from agricultural soils, including the use of nitrification and denitrification inhibitors, and the direct use of microorganisms to enhance NosZ activity. We focused on the screening and application strategies for microorganisms that can mitigate N2O emissions. We summarized two ecological mechanisms of microbial inoculation mitigation of N2O emissions from agricultural soils. One mechanism involved employing N2O-reducing microorganisms containing nosZ gene to directly mitigate N2O emissions from agricultural soils. The other mechanism utilized plant growth-promoting rhizobacteria to alter the community composition, abundance and activity of the N2O-producing or -reducing microorganisms and indirectly mitigate N2O emissions from agricultural soils. Additionally, we discussed the potential challenges affecting microbial inoculation technology, and explored its application prospects for reducing N2O emissions from agricultural soils. By providing a comprehensive overview of these topics, we aimed to effectively design and apply microbial-mediated mitigation technologies to better manage and mitigate N2O emissions from agricultural soils, ultimately contributing to global climate change mitigation efforts.