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

Alternate wetting and drying irrigation (I_AWD) is a promising practice for water conservation and climate mitigation, yet it inadvertently stimulates substantial nitrous oxide (N₂O) emissions. While previous research has largely focused on surface N₂O fluxes, the processes governing N₂O accumulation and emission across the soil profile-surface continuum remain poorly understood.

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 N₂O concentrations (0-50 cm depth, at 10-cm intervals) and concurrent surface fluxes.

The results showed that N₂O 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 N₂O 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 N₂O emissions.

Altogether, 0-20 cm soil profiles are the hotspots for N₂O accumulation in I_AWD paddy fields, and the N₂O accumulated in 10-20 cm soil profile dominates the N₂O emissions. These findings contribute to the adoption of straightforward and targeted N₂O mitigation strategies in I_AWD paddy fields.