Dynamics of deep soil carbon - insights from C-14 time series across a climatic gradient

Tessa Sophia van der Voort*, Utsav Mannu, Frank Hagedorn, Cameron McIntyre, Lorenz Walthert, Patrick Schleppi, Negar Haghipour, Timothy Ian Eglinton

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

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 similar to 1-9 degrees C) gradient are determined using time-series (similar to 20 years) C-14 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 2 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.

Original languageEnglish
Pages (from-to)3233-3246
Number of pages14
JournalBiogeosciences
Volume16
Issue number16
DOIs
Publication statusPublished - 29-Aug-2019
Externally publishedYes

Keywords

  • DISSOLVED ORGANIC-CARBON
  • FOREST SOILS
  • ATMOSPHERIC RADIOCARBON
  • AGRICULTURAL SOILS
  • MATTER
  • TURNOVER
  • STABILIZATION
  • MECHANISMS
  • NITROGEN
  • SEQUESTRATION

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