Soil carbon (C) improves soil health and soil fertility, while also acting as an important reservoir of terrestrial carbon and a potential sink for atmospheric CO2. Shifts in management practices, including the use of cover crops within rotations, has been proposed as a way to increase soil C levels. Still, the specific effects of soil type and cover crop species on soil C accumulation are not known. In this study, we collected 86 studies which compared agricultural production with and without cover cropping, and integrated those data into a soil health database (SoilHealthDB). Using this database, we conducted a meta-analysis to explore interactions between cover crops, soils, and carbon.
Results/Conclusions
Cover crops resulted in significant increases in soil carbon in coarse-textured (increase of 20%) and fine-textured (increase of 21%) soils, but no significant increase was observed for medium-textured soil. Likewise, neither cover crop type nor years of cover crop inclusion were associated with significant differences in soil carbon. A regression analysis revealed that soil carbon was positively correlated with cover crop dry biomass, but negatively correlated with the carbon to nitrogen ratio (C/N) of cover crop biomass. Altogether, cover cropping caused a 9% increase in soil carbon (95% confidence interval of 4% to 15%), indicating that the inclusion of cover crops into agricultural rotations can enhance soil carbon levels while potential increasing agroecosystem resilience.