Summary
This meta-analysis synthesised 14 controlled laboratory studies to clarify how prior soil moisture history affects N₂O release during rewetting—a common field phenomenon termed a 'hot moment'. The degree of soil rewetting and post-rewetting WFPS were significant predictors of emission magnitude, with exponential increases once soil became anaerobic. Microbial priming of substrate availability, rather than substrate concentration alone, emerged as the likely causal mechanism, though substantial uncertainty remains regarding how microbial community structure and gene expression respond to drought–wet cycles.
UK applicability
Findings are directly applicable to UK arable and grassland soils, which experience natural drought–rewetting cycles; understanding these dynamics is relevant to predicting seasonal N₂O losses and informing fertiliser management. However, the review notes a gap regarding the relationship between drought duration and subsequent emissions, limiting predictive capacity for variable UK weather patterns.
Key measures
Nitrous oxide (N₂O) emissions (likely in mg N₂O–N per kg soil or similar units); water-filled pore space (WFPS); antecedent moisture conditions; substrate availability; fertiliser quantity and type
Outcomes reported
A meta-analysis of 14 studies (130 data points) examining how antecedent soil moisture conditions influence nitrous oxide emissions during rewetting events. The analysis quantified the effects of water-filled pore space (WFPS), drought severity, substrate availability, and fertiliser type on N₂O emission magnitudes.
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