Site-specific field management adaptation is key to ensuring food security under climate change

Rapid climate change and growing population threaten global food security across the globe. Several studies have proposed early planting, increased irrigation, and increased fertilizer applications as climate adaptation strategies, yet none has considered combined and site-specific field management strategies as a comprehensive solution. Here, we analyzed wheat yield responses to climate change and field management adaptation using a mechanistic crop model evaluated against observed global rainfed wheat-yield over ten years at 3,767 sites (r²=0.78). We estimated that spatially heterogeneous adaption strategies had the potential to improve global wheat yields by 90% by 2100 compared to the present day. The yield improvements from combined field adaptation strategies were larger than the sum of improvements from the individual strategies. These synergistic benefits were shown to result from complementary processes regulating nutrient and water uptake, physiological tolerance to heat stress, and internal carbon and nutrient cycling. Early planting with longer-maturing varieties provided the most benefit to future yields. Improved water use efficiency from increased CO₂ led to relatively low benefits of additional irrigation. However, the yield gains from additional increased fertilizer application resulted in substantial nitrogen losses as leachate and N₂O emissions, in contrast to irrigation and planting date management adaptations. We conclude that without constraints on increasing fertilizer rates and advances in plant engineering of nitrogen acquisition, sustainable yield improvements are unlikely to meet growing wheat demand.