Assessing long-term greenhouse gas emissions, crop productivity and sustainability strategies in rotation-based potato systems of Prince Edward Island using the DNDC model

Potato cultivation plays a critical role in global food security, and understanding agricultural management is required to optimize crop yield, improve soil health and regulate greenhouse gas (GHG) emissions. This study calibrated and validated the process-based DNDC model using data from three experimental sites over two years (2023–2024) in Prince Edward Island (PEI), Canada’s smallest province but a major potato producer, to evaluate the long-term (1981–2024) effects of legume rotations (LR) in rainfed potato systems on soil health, crop productivity, and GHG emissions. Irrigation and nitrogen (N) fertilizer application scenarios were also assessed as potential sustainability strategies. The DNDC model accurately captured potato yield, reflecting sensitivity to water availability, and reproduced N 2 O and CO 2 flux patterns, despite some uncertainties. Sensitivity analysis indicated that potato yield was primarily influenced by soil physical properties, while soil properties and microbial activity-controlled N 2 O and CO 2 emissions, highlighting the importance of management practices targeting these factors. Long-term LR system indicates increased soil organic carbon and nitrogen, improving soil health and system resilience. Compared to non-legume rotations (NLR), LR provided a nitrogen credit of about 30 kg N ha −1 , while its global warming potential remained comparable to NLR over the rotation period. These results suggest clear agronomic benefits of LR rotations, but economic assessments over the rotation period are needed to better support farmers and policymakers. Scenarios combining different irrigation levels) no irrigation (IR0), full irrigation (IR100), 75% of full irrigation (IR75), and 50% of full irrigation (IR50)(and nitrogen application rates (full conventional rate (150 kg N ha −1 , N100) and reduced rates of 90% (N90), 85% (N85), and 80% (N80) of the conventional rate) were assessed. Based on the results, supplemental irrigation increased yield, particularly during drought years, but also raised GHG emissions, highlighting a trade-off between productivity and environmental impact. Evaluation using clustering and TOPSIS indicates that IR50N90, IR50N100, and IR75N90 are the most reliable management scenarios, suggesting that nitrogen fertilizer should be maintained near recommended levels, while deficit irrigation can sustain yields and reduce GHG emissions, particularly when combined with precision agriculture techniques.