Potential for Soil Carbon Sequestration in the US Great Plain Agricultural Region: Quantifying Management and Climate Driven Changes

Abstract:

The US Great Plain is an important agricultural region that is characterized by strong climatic gradients and land cover land use changes (LCLUC) of varying intensities. While the effects of climate and LCLUC on soil organic carbon (SOC) have been well evaluated in this region, there is limited understanding of the carbon sequestration potential following cropland management practices. In this study, we first modified and calibrated the DAYCENT biogeochemical model to improve the representation of the SOC dynamics. We then performed historical (1895-2005) simulation of SOC changes using spatially explicit datasets on climate, LCLUC and land management practices to estimate the contemporary SOC. Finally, we developed two-climate (increase in global warming by 3.8^oC and 6.0^oC in 2100), two-land cover (increase in cropland area by 23% and 53% in 2100) and four-land management (business as usual; BAU, no-till; NT, cover crop; CC and no-till + cover crop; NTCC) scenarios to quantify the effects of these environmental and management changes on SOC during 2006-2100. The future climate and land cover data are part of the Intergovernmental Panel on Climate Change (IPCC) higher and intermediate warming scenarios with different rates of economic growth and environmental conservation. Our preliminary results show that under BAU management, there is a climate change induced loss of 5.3 tC/ha in croplands and 6.7 tC/ha in grasslands. However, the NTCC was able to offset the climate change induced losses in SOC, resulting in a relative gain of 7.5 tC/ha and 7.8 tC/ha compared to the BAU under higher and intermediate rates of future land cover change; respectively, by the end of 21^st century. Strong regional patterns were found with greater management induced SOC sequestration in areas with projected increase in precipitation. These results have implications for guiding future cropland management and climate change mitigation in the US Great Plains and beyond.