Soil organic carbon dynamics in a long-term no-tillage and cover crop system in the Southeast United States

Climate-smart agriculture management practices such as no-tillage (NT) and cover crops offer multiple benefits (e.g., increased soil carbon stocks) and mitigate the short- and long-term effects of climate change on crop production. Integrating agroecosystem modeling and field experiment observations of NT and cover crops, we first examined the synergistic effect of NT-cover crops on soil carbon dynamics during the past five decades. Field observations and simulation results show that with cover crops NT leads to greater carbon gains in the topsoil than conventional tillage (CT). Model attribution analysis further suggest that: 1) soil carbon sequestration was highly correlated to biomass carbon inputs from both winter rye cover crop and the maize cropping system; 2) elevated CO2 and warming effects were the main contributors to benefiting soil carbon gains through promoting cover crop growth. The model projections show that soil organic carbon would increase with NT-cover crops management in high-emissions scenarios during 2019-2099, largely due to enhanced cover crop biomass production. Our study indicates that cover crops are of vital importance for soil carbon sequestration, and a combination of NT and cover crops would be an effective management strategy for climate change mitigation.