Hotspots of N2O accumulation in the soil profile of alternate wetting and drying paddy fields

Introduction Alternate wetting and drying irrigation (I AWD ) is a promising practice for water conservation and climate mitigation, yet it inadvertently stimulates substantial nitrous oxide (N 2 O) emissions. While previous research has largely focused on surface N 2 O fluxes, the processes governing N 2 O accumulation and emission across the soil profile–surface continuum remain poorly understood. Methods Here, we present a comprehensive dataset from a lysimeter study on paddy fields under I AWD and continuously flooded irrigation (I CF ), integrating measurements of soil N 2 O concentrations (0–50 cm depth, at 10-cm intervals) and concurrent surface fluxes. Results The results showed that N 2 O predominantly accumulated in 0–20 cm soilprofiles during the tiller fertilizer period (TF) and panicle fertilizer period (PF) regardless of the irrigation regimes. Compared to I CF , I AWD significantly increased the N 2 O concentrations in 0–30 cm soil profiles by 19.6–49.3% and 60.0–79.0% during the TF and PF, respectively. Partial least-squares path model further identified the 10–20 cm layer as the dominant hotspot, exerting the strongest direct control on surface N 2 O emissions. Discussion Altogether, 0–20 cm soil profiles are the hotspots for N 2 O accumulation in I AWD paddy fields, and the N 2 O accumulated in 10-20 cm soil profile dominates the N 2 O emissions. These findings contribute to the adoption of straightforward and targeted N 2 O mitigation strategies in I AWD paddy fields.