Cultivar and Soil Effects on Growing Season and Production-Scaled N2O Emissions from Prairie Potato Systems

Agricultural soils are a significant source of nitrous oxide (N2O), a potent greenhouse gas. Potatoes, with their low nitrogen use efficiency (NUE) and high nitrogen (N) demand, present a high risk of N2O emissions. Investigating factors influencing N2O production, including crop cultivar and soil environment, is needed to reduce emissions from Prairie potato production. This two-year study in Saskatchewan monitored N2O emissions from three potato cultivars (Clearwater Russet, Dark Red Norland, and Sangre) on two sites (clay loam and sandy loam), and evaluated the effect of soil micro-topography by measuring emissions from hill and furrow positions. Daily N2O flux, cumulative growing season emissions, yield-scaled, and tuber N-scaled emissions were quantified. Cumulative growing season emissions ranged from 164-848 g N2O N ha-1, aligning with other Prairie research but lower than more humid regions, likely due to lower precipitation on the Prairies. Although cultivars produced similar cumulative emissions, production-based analyses revealed Dark Red Norland and Sangre had 35-67% lower yield-scaled N2O than Clearwater Russet. Emissions were higher from hills than furrows at three of four site-years, suggesting variability in N2O production processes, likely related to substrate availability and moisture. This study highlights the complexity of soil and environmental interactions – encompassing differences in soil micro-topography, growing seasons, and soil characteristics – in driving N2O emissions. Significant negative relationships were found between NUE (tuber NUpE) and N2O emissions, demonstrating that selecting cultivars for agronomic performance (high yield and high NUE) may be a practical strategy to reduce production-based N2O emissions from potato production.