Optimising crop calendars with management practices promotes climate-smart agriculture in wheat-maize rotations of the North China Plain

Optimising crop calendars by adjusting sowing dates and the timing and frequency of key management practices can enhance crop productivity while reducing greenhouse gas (GHG) emissions. However, limited research has explored how farmers dynamically adapt crop calendars and practices in response to climate shifts to support climate-smart agriculture. This study developed a DNDC-based hybrid modelling framework to evaluate adaptive management strategies for supporting climate-smart agriculture under future climate scenarios. We assessed three management levels: fertiliser application rates (level 1); fertiliser rates combined with crop calendar adjustments, including fertiliser timing, frequency, as well as sowing and harvesting dates (level 2) and level 2 plus irrigation and residue retention (level 3). The framework was designed to optimise management under multiple objectives, including increasing crop yield, SOC sequestration, while simultaneously reducing N input and GHG emissions. From 1990 to 2100, the optimised crop calendars were identified: delaying wheat basal fertilisation (+5 d,) while advancing top-dressing (−5 d), postponing wheat sowing (+5 d) and advancing maize sowing (−9 d); advancing both fertilisation events in maize (−9 d, −3 d); aligning irrigation with fertilisation; and adding one irrigation event during the maize bell stage. Compared with historical practices, these adjustments increased annual crop yields and NUE by 4.2 % and 15.8 %, respectively, while reducing net GHG emissions and GHG intensity by 5.1 % and 8.5 %, respectively. The optimised management reduced N inputs, irrigation water and residue retention by 17.2 %, 6.7 % and 20.0 %, respectively. These findings demonstrate that adaptive crop calendars can significantly advance climate-smart agriculture and should be incorporated into climate change impact assessments. • Optimised crop calendars increased yields while reducing N use and GHG emissions. • Incorporating irrigation and residue retention into optimisation further reduced emissions. • Climate-adaptive crop calendars alleviate maize yield losses under warming. • Soil carbon sequestration and lower inputs drive long-term GHG mitigation potential.