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

Summary

This laboratory study examined how soil carbon, nitrogen, and phosphorus dynamics respond to consecutive drying–rewetting cycles, comparing drying–rewetting treatments with continuously moist controls over 14 days. During the first drying period, drying–rewetting cycles significantly increased extractable ammonium, total oxidised nitrogen, and bicarbonate-extractable phosphorus, whilst rewetting produced a substantial CO₂ flux increase (55.4 µg C g⁻¹ d⁻¹). The findings suggest that whilst drying–rewetting events substantially perturb soil microbial biomass and nutrient availability, disentangling microbial from physical effects remains challenging, and understanding soil responses to changing moisture patterns will be increasingly important under future climate scenarios.

UK applicability

These findings are relevant to UK soil management as drying–rewetting cycles are expected to increase in frequency and intensity under projected climate change. The results may inform predictions of nutrient release and greenhouse gas emissions from UK agricultural and grassland soils under changing rainfall patterns.

Key measures

Extractable ammonium, total oxidised nitrogen, bicarbonate-extractable phosphorus, microbial biomass carbon (MBC), microbial biomass phosphorus (MBP), CO₂ flux (µg C g⁻¹ d⁻¹), N₂O emissions

Outcomes reported

The study measured short-term responses of carbon, nitrogen, and phosphorus concentrations, microbial biomass, and associated CO₂ and N₂O emissions during two consecutive drying–rewetting cycles over 14 days. Results quantified changes in extractable ammonium, total oxidised nitrogen, bicarbonate-extractable phosphorus, and microbial biomass under alternating moisture conditions.

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