Persistent soil carbon enhanced in Mollisols by well-managed grasslands but not annual grain or dairy forage cropping systems

Abstract

Significance Soil organic carbon (C) responses to agricultural management are highly uncertain, hindering our ability to assess the C sequestration potential of croplands and develop sound policies to mitigate climate change while enhancing other ecosystem services. Combining experimental evidence from a long-term field experiment and a meta-analysis of published literature, we show that the accrual of mineral-associated soil C in intensively managed Mollisols was only achieved by managing ruminant grazing on perennial grasslands. Although modifying dominant grain-based systems with reduced tillage, diversified rotations, and legumes and manure additions improve soil health metrics—which is critical to soil, nutrient, and water conservation—they are unlikely to enhance persistent forms of soil C in Mollisols to help drawdown atmospheric C and stabilize climate.