Optimization of water and nitrogen measures for maize-soybean intercropping under climate change conditions based on the APSIM model in the Guanzhong plain, China

Climate change will significantly impact grain production in the Guanzhong Plain. Maize-soybean intercropping is a stable and efficient cropping system, and optimizing water and nitrogen (N) management strategies for this system under future climate is crucial for sustainable agriculture. We calibrated the Agricultural Production Systems Simulator (APSIM) model for maize-soybean intercropping under the Guanzhong Plain climate conditions and used the calibrated APSIM model to optimize the water and N strategy of maize-soybean intercropping for high productivity and efficiency under climate change. The APSIM model was calibrated by the data from two growing seasons field experiments. Historical meteorological data from 11 sites was used to evaluate the simulations of 25 Global Climate Models (GCMs) from the Coupled Model Inter-comparison Project phase 6 (CMIP6). The calibrated model was then used to select optimal water and N strategies from 416 setting strategies under future climate scenarios. No irrigation was needed in wet years. In normal years, supplemental irrigation of 50 mm during the maize three-leaf stage (soybean seedling stage) under the Shared Socio-economic Pathways2–4.5 (SSP245) scenario and 30 mm under the Shared Socio-economic Pathways5–8.5 (SSP585) scenario could ensure high yield and water use efficiency (WUE) in the intercropping system. In dry years, under the SSP245 scenario, supplementary irrigation of 70 mm during the maize three-leaf (soybean seedling stage) and tasseling stages (soybean podding stage), and for the SSP585 scenario, supplementary irrigation of 50 mm during the same stages could ensure high productivity and WUE. The optimal N application strategy in dry and normal years under the SSP245 scenario was a basal application of 100 kgN ha −1 for maize and soybean and a topdressing of 80 kgN ha −1 for maize, while in wet years, a basal application of 120 kgN ha −1 and a topdressing of 80 kgN ha −1 was optimal. Under the SSP585 scenario, the optimal N application strategy in dry and normal years was a base application of 100 kgN ha −1 for maize and soybean and a topdressing of 140 kgN ha −1 for maize, and in wet years, a basal application of 120 kgN ha −1 and topdressing of 140 kgN ha −1 was optimal. This study validates APSIM model for the Guanzhong Plain and provides precise water and N management guidelines for maize-soybean intercropping, ensuring food security and efficient resource utilization in future climate conditions. • The most suitable GCM for Guanzhong Plain from CMIP6 was selected for analysis. • The future climate change in the Guanzhong Plain was clearly identified. • The supplemental irrigation amount of the maize-soybean intercropping system was optimized. • The N application of the maize-soybean intercropping system was optimized.