This dataset contains information of the manuscript entitled "Persistent soil carbon enhanced in Mollisols by well-managed grasslands but not annual grain or dairy forage cropping systems".

Grasslands-derived Mollisols cover a large area globally and are usually under intensive agricultural production, which has liberated large amounts of carbon (C) into the atmosphere. Whether improved management practices such as no-till, diversified crop rotations, legumes and/or manure additions, or re-establishing perennial grasslands and integrating livestock can restore soil C on Mollisols is unclear. In this study, we utilized the Wisconsin Integrated Cropping Systems Trial (WICST), a long-term trial comparing conventional and alternative agricultural systems in the North Central USA, and studied soil C composition and persistence, and their relationships with soil microbial attributes after 29 years of different agricultural management. 

The soil C composition data include particulate organic matter (POM)-C, which is believed to be primarily plant-derived and unprocessed or partially processed by microbes, and mineral-associated organic matter (MAOM)-C, which is believed to be mostly microbial-derived and simple structured. These soil C fractions were obtained by physical fractionation (53 µm). Diffuse reflectance infrared fourier transform spectroscopy (DRIFTS) was used to study the composition of MAOM (Aliphatic C vs. Aromatic C).

Soil microbial attributes studied include soil microbial biomass C (by chloroform fumigation method), microbial C-use efficiency (CUE) (by ¹³C-tracing method), and microbial necromass (amino sugars biomarkers, including glucosamine, muramic acids, galactosamine, and mannosamine). Activities of oxidative enzymes were studied to assess the potential of soil organic matter oxidation under these different management regimes.

These data suggested that on the Mollisols, only perennial pastures that were managed by rotational grazing could enhance soil (0-30 cm) carbon stock and persistence compared to the conventional continuous corn system that had annual tillage. No-till did not increase soil C stock or persistence, while including legumes/manure in crop rotations could enhance microbial C cycling, but could not enhance the stock of persistent MAOM-C.