Winter canola integration improves carbon balance, biomass, and profitability in illinois corn–soybean systems

Context Sustainable intensification in the U.S. Midwest requires cropping strategies that enhance productivity and environmental outcomes without expanding land use. Winter oilseeds, particularly canola, are promising double crops in corn–soybean (CS) systems, yet their system-level (Corn–Canola–Soybean rotation system) impacts on yield, greenhouse gas (GHG) emissions, and profitability remain underexplored in the U.S. Midwest. Objective This study assessed the agroecosystem implications of winter canola integration into CS rotations, focusing on trade-offs among productivity, net ecosystem carbon balance (NECB), GHG intensity, and profitability under alternative nitrogen (N) management strategies. Method Using the process-based DayCent model, we simulated three two-year cycles (2019–2024) comparing conventional CS with corn-canola-soybean (CCS) systems across four N scenarios (0, 84, 140, and 167 kg N ha −1 ). Outputs were analyzed for crop yields, system-level biomass, NECB, GHG emissions, and net returns. Results and Conclusions CCS systems exhibited yield penalties for corn (3–5%) and soybean (11–19%) due to shortened growing seasons, yet system biomass increased by 13–17% with canola inclusion. Higher N demand elevated total GHG emissions in CCS, but system-level GHG intensity remained stable because biomass gains offset emissions proportionally. NECB improved by up to 26.5% under moderate to high N inputs, reflecting stronger carbon retention. Net returns increased by 10–23% relative to CS, driven by canola as an added cash crop. Together, these findings demonstrate that winter canola integration can intensify land use while maintaining emission efficiency and enhancing both carbon outcomes and farm profitability. Significance This study provides the first system-level assessment of winter canola in Midwestern CS rotations using process-based modeling. By linking agronomic management, environmental services, and profitability, it provides actionable insights for sustainable intensification and climate-smart diversification strategies that support U.S. decarbonization goals and Midwestern cropping system transitions toward resilient agricultural systems.