Summary
This global synthesis of 5438 paired observations, combined with three independent field studies, demonstrates that soil pH exerts primary control over nitrous oxide emission factors through its effect on denitrifier community composition. The research reveals a hump-shaped relationship between pH and EFs, with moderately acidic soils producing the highest emissions by favouring N₂O-producing over N₂O-consuming microorganisms. These findings provide a mechanistic foundation for predicting and mitigating soil N₂O emissions under future nitrogen input scenarios.
UK applicability
The pH–N₂O relationship identified in this global synthesis should apply to UK soils, where many agricultural soils operate in the moderately acidic to neutral range where peak emissions were observed. UK farmers and policy-makers could use these findings to inform liming strategies and nitrogen management decisions aimed at reducing greenhouse gas emissions, though site-specific pH and microbial community characterisation would be needed to optimise local mitigation approaches.
Key measures
Soil pH, N₂O emission factor (EF), N₂O emission fluxes, N₂O/(N₂O + N₂) ratio, denitrification rate, denitrifier community composition
Outcomes reported
The study analysed 5438 paired data points of N₂O emission fluxes and conducted three field studies to determine the relationship between soil pH and nitrous oxide emission factors (EFs), and the underlying mechanisms involving denitrifier microorganism communities.
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