Feasible crop reallocation under stage-specific climate stress in China

Crop reallocation is commonly proposed as a climate-adaptation strategy; however, its system-level effects remain uncertain when crop phenological sensitivity, existing crop shares, and production safeguards are considered together. This study evaluates feasible reallocation of maize, rice, soybean, and wheat across China under climate stress at different crop growth stages. Province-level production and crop-area data were combined with phenological-stage indicators of drought, heat, and compound stress. Crop-specific fixed-effects regressions linked compound climate stress to expected productivity, which was then incorporated into a linear optimization model that reallocates provincial crop shares subject to historical crop-share bounds, province-specific switching limits, total cropped-area constraints, and crop-specific production floors. Across the 0.5×, 1.0×, and 2.0× switching-flexibility scenarios, climate-stress-adjusted national staple production increased by 0.96%, 1.69%, and 2.95%, respectively. Only the maize climate-response coefficient was statistically significant at the 5% level; however, setting the non-significant coefficients for rice, soybean, and wheat to zero produced nearly identical national gains and crop-allocation patterns. Rice accounted for the largest positive production adjustment, whereas soybean remained at its 95% production floor across all flexibility scenarios and wheat reached its production floor under the 2.0× scenario. Production responses also varied substantially among provinces, indicating that the benefits of constrained crop reallocation are spatially heterogeneous. These results show that feasible crop reallocation can provide a measurable but bounded increase in climate-stress-adjusted production within the land-allocation, switching, and production requirements represented in the model. The framework provides a spatially explicit approach for evaluating crop-reallocation options under stage-specific climate stress and defined agricultural constraints.