Old soil carbon is more temperature sensitive than the young in an agricultural field

Pekka Vanhala, Kristiina Karhu, Mikko Tuomi, Eloni Sonninen, Högne Jungner, Hannu Fritze, Jari Liski

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72 Citations (Scopus)


Changes in the carbon stock of soil in response to climate change would significantly affect the atmospheric carbon dioxide concentration and consequently climate. The isotopes of carbon provide a means to study the temperature sensitivities of different soil carbon fractions. Where C3 vegetation has changed for C4, soil organic matter (SOM) from the different origins have different 13C/12C ratios. Relying on this feature, we took soil samples from a control field and a field where ordinary grain (C3) vegetation was replaced by maize (C4), 5 years ago. We measured the respiration rate and the 13C/12C ratio of the CO2 produced by the samples at different temperatures. Based on these measurements, we quantified that Q10 was 3.4-3.6 for the total CO2 production while it was 2.4-2.9 at 20 °C for the maize-derived young carbon and 3.6 for the older C3-derived carbon. Our results suggest that climatic warming will accelerate especially the decomposition of the large pool of old soil carbon in these fields.

Original languageEnglish
Pages (from-to)2967-2970
Number of pages4
JournalSoil Biology and Biochemistry
Issue number11
Early online date26 Jun 2007
Publication statusPublished - 1 Nov 2007


  • Carbon dioxide
  • Carbon isotopes
  • Mineralization
  • Temperature sensitivity


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