Summary
This systematic review and meta-analysis synthesised evidence from 14 controlled experiments examining how prior drought conditions prime soils to emit larger quantities of N₂O when rewetted. The authors found that the magnitude of drought-to-wet transition and final soil WFPS were significant predictors of emissions 'hot moments', with exponential increases under anaerobic conditions, though they emphasise that microbial substrate bioavailability—rather than substrate concentration alone—likely drives the mechanism. The authors identify substantial gaps in understanding how microbial community structure and gene expression respond to antecedent dry-wet cycles, and recommend development of drought-impact curves linking emission magnitude to drought duration.
UK applicability
The findings are relevant to UK agriculture given projected increases in summer drought and precipitation variability under climate change, particularly for rainfed and grassland systems. However, the review is based on controlled laboratory experiments and includes temperate and Mediterranean climates; field validation under UK pedoclimatic conditions and integration with farm management practices would strengthen applicability.
Key measures
Nitrous oxide (N₂O) emissions (likely in μg N₂O-N per unit soil per unit time); water-filled pore space (WFPS); antecedent soil moisture conditions; substrate availability; fertiliser quantity and type
Outcomes reported
The study quantified how antecedent soil moisture conditions influence N₂O emissions during rewetting events through meta-analysis of 14 controlled experiments. It identified soil water-filled pore space (WFPS), drought intensity, substrate availability, and fertiliser application as key predictive variables for emissions magnitude.
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