SOIL, 7, 347–362, 2021 https://doi.org/10.5194/soil-7-347-2021 © Author(s) 2021. This work is distributed under SOIL the Creative Commons Attribution 4.0 License. Geogenic organic carbon in terrestrial sediments and its contribution to total soil carbon Fabian Kalks1, Gabriel Noren2, Carsten W. Mueller3,4, Mirjam Helfrich1, Janet Rethemeyer2, and Axel Don1 1Thünen Institute of Climate-Smart Agriculture, Bundesallee 65, 38116 Braunschweig, Germany 2Institute of Geology and Mineralogy, University of Cologne, Institute of Geology and Mineralogy, Zülpicher Str. 49b, 50674 Cologne, Germany 3Chair of Soil Science, School of Life Sciences, Technical University of Munich, Emil-Ramann-Strasse 2, 85354 Freising-Weihenstephan, Germany 4Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, 1350 Copenhagen K, Denmark Correspondence: Fabian Kalks (
[email protected]) Received: 19 May 2020 – Discussion started: 5 June 2020 Revised: 18 May 2021 – Accepted: 27 May 2021 – Published: 6 July 2021 Abstract. Geogenic organic carbon (GOC) from sedimentary rocks is an overlooked fraction in soils that has not yet been quantified but influences the composition, age, and stability of total organic carbon (OC) in soils. In this context, GOC is the OC in bedrock deposited during sedimentation. The contribution of GOC to total soil OC may vary, depending on the type of bedrock. However, no studies have been carried out to investigate the contribution of GOC derived from different terrestrial sedimentary rocks to soil OC contents. In order to fill this knowledge gap, 10 m long sediment cores from three sites recovered from Pleistocene loess, Miocene sand, and Triassic Red Sandstone were analysed at 1 m depth intervals, and the amount of GOC was calculated based on 14C measurements.