Impacts of Climate Change and Agricultural Practices on Nitrogen Processes, Genes, and Soil Nitrous Oxide Emissions: A Quantitative Review of Meta-Analyses

Summary

This comprehensive quantitative review employed mega-analysis to synthesise findings across multiple meta-analyses examining how climate change and agricultural management practices alter nitrogen-cycling microbial communities and soil nitrous oxide emissions. Key results indicate that global warming increases N₂O emissions by 159.7% through stimulation of nitrification and denitrification, nitrogen fertilisation increases emissions by 153.2%, elevated CO₂ increases them by 40.6%, and microplastics exposure increases them by 140.4%, whilst biochar application reduces emissions by 15.8% through enhanced nosZ expression. The findings elucidate mechanistic pathways by which environmental and management factors regulate microbial N-cycling genes and processes, with implications for agricultural greenhouse gas mitigation.

UK applicability

The findings are relevant to UK agricultural policy and practice regarding nitrogen management and climate change mitigation. The quantified effects of nitrogen fertilisation and biochar application on N₂O emissions are directly applicable to UK farming systems, though the global synthesis may mask regional variation in soil type, climate, and microbial communities that could affect outcomes under UK-specific conditions.

Key measures

Soil nitrification and denitrification rates; relative abundance of amoA (AOB and AOA), narG, nirS, nirK, and nosZ genes; soil N₂O emissions (expressed as percentage change from baseline); soil NH₄⁺-N and NO₃⁻-N contents

Outcomes reported

This mega-analysis (meta-meta-analysis) quantitatively assessed the effects of climatic factors and agricultural practices on nitrogen-cycling microbial genes, processes, and resulting soil N₂O emissions. The study measured changes in nitrification and denitrification rates, abundance of key functional genes (amoA, narG, nirS, nirK, nosZ), and soil N₂O emission levels under various environmental and management scenarios.

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