Projecting potential planting dates of global soybean and wheat under future climate change

Adapting agriculture to climate change requires reliable information to guide agronomic decisions. One critical factor is understanding shifts in planting dates, which directly influence crop productivity and resilience to climate change. In this study, we introduced the concept of “potential planting dates” (PPDs) to quantify variations in major crop planting dates based on specific climate and soil conditions. Using the Coupled Model Intercomparison Project Phase 6 (CMIP6) multi-model ensemble under four emission scenarios, we predicted spatial and temporal patterns in PPDs for wheat and soybean crops on a global scale from 2021 to 2100. Our results indicated that PPDs would advance by approximately 0.3, 0.7, 1.3, and 1.9 days per decade for spring wheat; and by 0.2, 0.6, 0.9, 1.3 days per decade for soybean under emission scenarios SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5, respectively. In contrast, PPDs for winter wheat would delay by 0.3, 1.2, 2.5, and 3.2 days per decade under the same scenarios. Overall, advanced PPDs were projected in approximately three-quarters of global spring wheat areas and two-thirds of soybean areas. Air temperature is projected to be a crucial factor affecting PPDs, particularly for spring wheat, where a 1 °C increase would result in an advancement of 4.3-6.3 days across the four scenarios. The global variability in PPDs increased with higher greenhouse gas emissions. These findings provide quantitative insights into projected shifts in PPDs under a changing climate, highlighting the potential for adaptive planting adjustments to mitigate some of its adverse impacts.