Abstract
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.