Modeling maize productivity and N2O emissions under surface and subsurface drip fertigation in current and future climates

Drip fertigation is a pivotal technology for conserving water in arid and semi-arid regions across the world. Recent field studies have shown that drip fertigation may also mitigate emissions of the powerful greenhouse gas nitrous oxide (N2O). However, existing process-based models have not been evaluated for simulating N2O emissions under drip fertigation systems, limiting our capacity to predict the environmental performance of these irrigation technologies under future climatic conditions. Here, we assessed the performance of the Canadian version of the DeNitrification-DeComposition model (DNDCv.CAN) in simulating N2O emissions from drip-fertigated maize systems. The model was calibrated and validated using a comprehensive two-year dataset from a field experiment in Spain that included subsurface and surface drip irrigation with four nitrogen (N) fertigation treatments: ammonium sulfate (AS), AS with nitrification inhibitor DMPP (AS_DMPP), calcium nitrate (CN), and a control without N (N0). The calibrated model adequately simulated crop yield (RMSE < 1.84 Mg ha−1), grain N content (RMSE < 18 kg N ha−1) and cumulative N2O emissions (RMSE < 0.06 kg N ha−1) across all treatments, with R2 values of 0.3–0.7 and d-index above 0.6. The model also generally captured the observed treatment responses to N fertilizer management and irrigation placement, including the occurrence of peak N2O emissions. Compared to the baseline (1981–2010), projections using DNDCv.CAN by 2100 under SSP2–4.5, SSP3–7.0, and SSP5–8.5, indicated that both surface and subsurface drip fertigation will likely experience yield reductions (-56.2% ~ −14.6%) and increased N2O emissions (27.2% ~ 52.7%). Within these future scenarios, subsurface drip irrigation produced similar yields while reducing N2O emissions compared with surface drip systems. Among all treatments, the combination of AS_DMPP or CN fertilizers with subsurface drip irrigation performed best, achieving lower emissions without compromising yields. Increasing heat stress emerged as the primary driver of future yield losses and elevated N2O emissions due to higher residual soil N. Adaptation strategies, such as earlier sowing paired with longer‑season, higher‑yielding cultivars, may help sustain productivity but could also increase N2O emissions, highlighting important trade‑offs that must be considered when designing and implementing climate‑resilient management practices.