Soil Organic Carbon and Nitrogen Feedbacks on Crop Yields under Climate Change

Core Ideas SOC decline, due to increased temperatures, reduces wheat and maize yields globally. CO 2 increase to 540 ppm partially compensates yield losses due to increased temperatures. Accounting for soil feedbacks is critical when evaluating climate change impacts on crop yield. A critical omission from climate change impact studies on crop yield is the interaction between soil organic carbon (SOC), nitrogen (N) availability, and carbon dioxide (CO 2 ). We used a multimodel ensemble to predict the effects of SOC and N under different scenarios of temperatures and CO 2 concentrations on maize ( Zea mays L.) and wheat ( Triticum aestivum L.) yield in eight sites across the world. We found that including feedbacks from SOC and N losses due to increased temperatures would reduce yields by 13% in wheat and 19% in maize for a 3°C rise temperature with no adaptation practices. These losses correspond to an additional 4.5% (+3°C) when compared to crop yield reductions attributed to temperature increase alone. Future CO 2 increase to 540 ppm would partially compensate losses by 80% for both maize and wheat at +3°C, and by 35% for wheat and 20% for maize at +6°C, relative to the baseline CO 2 scenario.