Mapping nitrous oxide emissions across soil water gradients in agricultural fields

Nitrous oxide (N₂O) emissions in agricultural fields exhibit substantial spatial and temporal variability, driven by complex interactions between soil water dynamics and landscape features. We conducted field experiments at two agricultural field sites (Tokkerup and Taastrup) in Eastern Denmark to quantify N₂O emissions across soil water gradients. At the Tokkerup site, we quantified the effects of soil water drainage by comparing well-drained and poorly-drained areas. We installed manual and automated chambers to capture the spatial and temporal dynamics of N₂O emissions, complemented by continuous monitoring of soil water tables and moisture contents with water wells and soil moisture sensors. At the Taastrup site, we investigated N₂O emissions across a soil-water gradient. Twelve spatial spots were selected along a transect across the water gradient to measure N₂O fluxes using an Aeris MIRA Ultra analyzer equipped with a manual chamber. Soil water wells and sensors were installed across the gradient to capture the dynamics of water table depths and soil moisture across the field gradient throughout the year. Preliminary results reveal that significantly higher N₂O emissions occurred along the periphery of depressions in the field, so these transition areas acted as hot spots of N₂O emissions during the crop-growing period. These findings highlight the critical role of soil water dynamics in shaping the temporal and spatial N₂O emission patterns and emphasize the potential for soil water management as an important part of strategies to mitigate emissions of N₂O.