Soil organic carbon sustaining maize yields in China

With a rapidly increasing global population and increasing uncertainty over food security, farmers are facing a dilemma of producing crops with a higher yield on the same (or even less) cultivated areas. More specifically, the mean growth rate of global crop yield must exceed 2.4% per year to feed 10 billion people by 2050s. However, the ongoing climate crisis is preventing farmers from fulfilling this goal. As current farming systems are normally designed to fit into historical climate conditions, climate change-induced changes of meteorological factors are expected to pose significant risks for future farming outputs.

Temperature is commonly reported as a key factor affecting maize yield and any changes beyond the optimal zone are likely to cause detrimental impacts on maize yields. However, less is known about how soil can modulate the region-specific impacts and whether certain soil properties can buffer the adverse impacts of climate warming. In this study, we used the Agricultural Production Systems sIMulator (APSIM) model, to investigate the impacts of multiple soil biological and physical (e.g. soil carbon and soil plant available water) properties on the responses of maize yield to growing season temperature (S_Y,T) between 1961 and 2016 in China’s maize belt. Our objectives were to address the following questions: I) how does maize yield respond to climate warming in different zones of China’s maize belt? II) how do various soil physical, hydraulic, and chemical properties modulate the impacts of climate warming on maize yield? By answering these we provide insights into the development of adaptive strategies for global warming from the perspective of soil interventions.

Results indicated a greatly varied S_Y,T across regions with a large yield decline of 11.2% for each 1 °C warming in the mid-eastern region of the belt but a small increase of 1.5% in the north-eastern region. We found that the variations of soil inherent properties was able to explain around 77% of the spatial variations of S_Y,T. Among the included properties, soil organic carbon content (SOC) contributed most, showing positive impacts on maize yield. We also found that the regions with low S_Y,T were those areas with high SOC content. Our findings highlight the importance of SOC in the mitigation of adverse global warming impacts. SOC is an important indicator of soil quality and soils with higher SOC tend to show better water and nutrient retention, which can then help crops buffer the impacts of increased temperature and even exploit positive effects. To ensure food security for a rapidly increasing population under a changing climate, appropriate farming management practices that improve soil quality (especially SOC) can provide farmers with a natural insurance against climate warming through a gain in yield stability and more resilient production in China’s maize belt.