Undervine groundcover substantially increases shallow but not deep soil carbon in a temperate vineyard

Soil carbon may be enhanced in agroecosystems by increasing root density throughout the soil profile. In vineyards and orchards, groundcovers that grow concurrently with the grapevines directly increase shallow root biomass and may induce deeper rooting of the fruit crop. We examined root distributions and soil properties associated with soil carbon in a vineyard that varies in groundcover and rootstock management practices. In comparison to an herbicide control, the grass groundcover substantially increased root biomass inputs in shallow soil zones (<40 cm) and appreciably influenced grapevine root mass distribution throughout the soil profile. Groundcover root growth enhanced soil carbon and nitrogen by nearly 50 % between 0−40 cm depths, but there was no significant influence of groundcover or rootstock on soil parameters at deeper depths (> 40 cm). Collectively, our results suggest that undervine groundcovers can substantially increase shallow soil carbon, but the potential for increases beyond the groundcover root zone remains unclear.