Data from: Cover crop root contributions to soil carbon in a no-till corn bioenergy cropping system

Crop residues are potential biofuel feedstocks, but residue removal may
reduce soil carbon (C). The inclusion of a cover crop in a corn bioenergy
system could provide additional biomass, mitigating the negative effects
of residue removal by adding to stable soil C pools. In a no-till
continuous corn bioenergy system in the northern US Corn Belt, we used
13CO2 pulse labeling to trace plant C from a winter rye (Secale cereale)
cover crop into different soil C pools for 2 years following rye cover
crop termination. Corn stover left as residue (30% of total stover)
contributed 66, corn roots 57, rye shoots 61, rye roots 50, and rye
rhizodeposits 25 g C m−2 to soil. Five months following cover crop
termination, belowground cover crop inputs were three times more likely to
remain in soil C pools than were aboveground inputs, and much of the
root-derived C was in mineral-associated soil fractions. After 2 years,
both above- and belowground inputs had declined substantially, indicating
that the majority of both root and shoot inputs are eventually
mineralized. Our results underscore the importance of cover crop roots vs.
shoots and the importance of cover crop rhizodeposition (33% of total
belowground cover crop C inputs) as a source of soil C. However, the
eventual loss of most cover crop C from these soils indicates that cover
crops will likely need to be included every year in rotations to
accumulate soil C.