Quantitative constraints on soil organic matter (SOM) dynamics are essential for comprehensive understanding of the terrestrial carbon cycle. Deep soil carbon is of particular interest, as it represents large stocks and its turnover times remain highly uncertain. In this study, SOM dynamics in both the top and deep soil across a climatic (average temperature ~1-9 °C) gradient are determined using time-series (~20 years) 14C data from bulk soil and water-extractable organic carbon (WEOC). Analytical measurements reveal enrichment of bomb-derived radiocarbon in the deep soil layers on the bulk level during the last two decades. The WEOC pool is strongly enriched in bomb-derived carbon, indicating that it is a dynamic pool. Turnover time estimates of both the bulk and WEOC pool show that the latter cycles up to a magnitude faster than the former. The presence of bomb-derived carbon in the deep soil, as well as the rapidly turning WEOC pool across the climatic gradient implies that there likely is a dynamic component of carbon in the deep soil. Precipitation and bedrock type appear to exert a stronger influence on soil C turnover time and stocks as compared to temperature.

Data_and_code_Van_der_Voort_et_al_2019_BiogeosciencesThis zip file contains all the code and data accompanying the paper: Dynamics of deep soil carbon - insights from 14C time series across a climatic gradient (Van der Voort et al., Biogeosciences, 2019). The data of each figure can be found in the excel file. The MatLab codes referenced in the paper can also be found in the zip file. They are thoroughly commented so that users can easily re-use it.Time_Series_Data_Repo_Folder_Dryad.zip