Use of a Process‐Based Model to Predict Nitrous Oxide Emissions From Intensive Crop Production Under a Changing Climate

ABSTRACT In cold temperate regions, nongrowing season (November‐April) nitrous oxide (N 2 O) emissions from croplands can be substantial, particularly during the rapid freeze‐thaw cycles of the late winter‐spring. Despite their potential environmental impact, the extent and underlying climatic triggers of these emissions remain poorly understood. Using the Denitrification and Decomposition (DNDC) model, N 2 O fluxes and climatic triggers of N 2 O emissions were assessed by simulating historical (1990–2019) and 30‐year future (2038–2067) winter and early spring emissions under intensive grain corn production in Southern Quebec. In the historical period, mean winter N 2 O emissions were greatest in warm‐wet years, and increased over the years as the snow‐water equivalent (SWE) declined. Future scenario simulations predict a 10% increase in winter/spring N 2 O emissions, driven by a 1°C rise in winter soil temperature and an 8% increase in water‐filled pore space (WFPS). SWE is also expected to decrease by 1 mm annually. These shifts suggest a substantial increase in future winter N₂O emissions, highlighting the urgency of developing mitigation strategies for agricultural soils.