Responses of carbon, nitrogen and phosphorus to two consecutive drying–rewetting cycles in soils

Summary

This controlled laboratory study examined how two successive drying-rewetting cycles affect soil nutrient availability and microbial activity over 14 days, compared to continuously moist conditions maintained at 60% water holding capacity. The first drying period increased extractable ammonium, total oxidized nitrogen, and bicarbonate-extractable phosphorus, whilst rewetting produced elevated CO₂ flux (55.4 µg C g⁻¹ d⁻¹). The authors highlight the need to understand combined carbon, nitrogen, and phosphorus responses to changing soil moisture regimes under future climate scenarios, whilst acknowledging the difficulty of isolating microbial from physical effects of drying-rewetting perturbation.

UK applicability

The findings are directly relevant to UK soil management under projected climate change scenarios involving more frequent and intense drought-rewetting cycles. Understanding these nutrient mobilisation patterns and associated greenhouse gas emissions could inform agricultural practices and soil monitoring protocols in UK farming systems.

Key measures

Extractable ammonium, total oxidized nitrogen, bicarbonate-extractable phosphorus, microbial biomass carbon (MBC), microbial biomass phosphorus (MBP), CO₂ flux (µg C g⁻¹ d⁻¹), N₂O emissions, soil moisture content (% water holding capacity)

Outcomes reported

The study measured short-term responses of extractable carbon, nitrogen, and phosphorus pools, microbial biomass C and P, and CO₂ and N₂O emissions in soils subjected to two consecutive drying-rewetting cycles versus continuously moist conditions over a 14-day incubation period.

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