14C content of specific organic compounds in subsoils
Although over 50% of the global terrestrial organic carbon pool is found in soils below 30 cm depth, the subsoil below the A-horizon is generally not considered in carbon turnover models and has received far less scientific attention than the topsoil. Another reason is that the investigation of subsoil phenomena and processes poses major methodological, instrumental and analytical challenges. Organic carbon concentrations are one to two orders of magnitude lower than in topsoils, fine root and microbial densities decrease by several orders of magnitude with depth. This project will face these challenges with a trans-disciplinary team of soil scientists applying innovative approaches. It will focus on comprehensively characterizing subsoil carbon pools, on analyzing gaseous and liquid carbon fluxes, and on determining the factors controlling subsoil carbon dynamics.
Subproject 3 investigates organic matter transformation from surface to subsoil horizons using lipid biomarkers and 14C analysis.