SUBSOM - The Forgotten Part of Carbon Cycling: Organic Matter Storage and Turnover in Subsoils
Soils contain the largest carbon (C) pool of the global terrestrial C cycle. More than 50% of the C stocks are stored in deeper soil horizons. The processes of C stabilization in soils and how they are affected by anthropogenic activities are current research topics.
The collaborative research project SUBSOM (DFG-research group), which combines nine sub-projects, investigates the key issues of the C-dynamics in subsoils. This will give a better understanding of the factors controlling C turnover and fluxes in the subsoil. Due to very low C concentrations and high spatial variability of soil properties and processes, the investigations in the subsoil pose major methodological, instrumental and analytical challenges. The SUBSOM project will face these challenges applying innovative approaches such as the use of combined stable and radiocarbon isotope analysis. Within the framework of the SUBSOM project, the Thünen Institute of Climate-Smart Agriculture investigates the CO2 production and the factors influencing the turnover of C in subsoils. The main objectives are:
The study site was established in summer 2013 and it is located in a deciduous forest near to Hannover. On the site three accessible soil observatories were installed in 2 m depth. In each soil observatory CO2-concentration will be measured continuously in five different depths. In addition, gas samples will be taken at the same depths several times a year and these samples will be analysed on radiocarbon and stable C isotopes. In order to get information of vertical dynamics of C in soils 13C-labeled leaf litter will be exposed one on half at all three soil observatories in autumn 2014.
Additionally, laboratory incubation experiments will be carried out in order to investigate the key factors for C turnover in subsoils.
5.2013 - 12.2020
Project funding number: HE 6877/1-1 und DO-1734/4-2
Project status: ongoing