Data from: Soil carbon accumulation differences: allocation of visible plant biomass, carbon and nitrogen in two turfgrasses

Carbon accumulation in turfgrass soils by plant material may be beneficial to CO2 sequestration and soil health, but at high rates can easily lead to declined turfgrass quality (i.e. thatch and mat layer formation). In a field study it was investigated how the fraction of visible plant biomass of turfgrass (sub)species monocultures, with two or three varieties  as monoculture per (sub)species, and its C and  N concentration and CN ratio in this visible plant biomass in thatch, mat and soil layers contributes to C accumulation. In total three Festuca rubra subspecies; Festcua rubra commutata (Frc), Festuca rubra trichophylla (Frt), Festuca rubra rubra (Frr), and three Agrostis species; Agrostis canina (Acn), Agrostis capillaris (Acp), Agrostis stolonifera (As), were studied. The study was conducted on 3 years old turfgrass demonstration fields of two turfgrass seed companies: Festuca rubra subspecies samples were collected at a site of Barenbrug in Wolfheze (52°00´N, 5°46´E), and Agrostis species were sampled at a site of DLF in Moerstraten (51°32´N, 4°20´E), both in the Netherlands. Both sites were built on a sandy soil. 

For every variety, cores of the top 20 cm of the soil including aboveground biomass were taken with a core sampler (diameter 28 mm). The core was immediately divided into 4 distinctive layers, thatch + aboveground biomass, mat, remaining upper 10 cm soil and 10-20 cm soil. Distinction of these layers followed the protocol of Evers et al. (2024). Aboveground biomass was separated from the thatch with scissors. Sediment from thatch, mat, remaining upper 10 cm of soil and 10-20 cm soil was carefully washed out with tap water, after which the remaining below-ground (dead and living) visible plant biomass and aboveground biomass was dried at 65 °C until stable weight and weighed. Total C and N analyses were carried out with a Vario Micro Cube Element Analyzer (Elementar, Langenselbold, Germany), from which C and N concentrations (in % of dry matter of plant biomass) and C to N ratios (CN ratio) were calculated.