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Evolution of the δ13C signature related to total carbon contents and carbon decomposition rate constants in a soil profile under grassland

Authors

  • Frederik Accoe,

    Corresponding author
    1. Department of Applied Analytical and Physical Chemistry, Faculty of Agricultural and Applied Biological Sciences, Ghent University, Belgium
    2. Department of Soil Management and Soil Care, Faculty of Agricultural and Applied Biological Sciences, Ghent University, Belgium
    • Department of Applied Analytical and Physical Chemistry, Faculty of Agricultural and Applied Biological Sciences, Ghent University, Coupure Links 653, 9000 Gent, Belgium.
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  • Pascal Boeckx,

    1. Department of Applied Analytical and Physical Chemistry, Faculty of Agricultural and Applied Biological Sciences, Ghent University, Belgium
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  • Oswald Van Cleemput,

    1. Department of Applied Analytical and Physical Chemistry, Faculty of Agricultural and Applied Biological Sciences, Ghent University, Belgium
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  • Georges Hofman,

    1. Department of Soil Management and Soil Care, Faculty of Agricultural and Applied Biological Sciences, Ghent University, Belgium
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  • Ying Zhang,

    1. Institute of Applied Ecology, Chinese Academy of Science, Shenyang, China
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  • Rong hua Li,

    1. Institute of Applied Ecology, Chinese Academy of Science, Shenyang, China
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  • Chen Guanxiong

    1. Institute of Applied Ecology, Chinese Academy of Science, Shenyang, China
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  • Presented at SIMSUG 2002, Belfast, UK.

Abstract

Evolution of the total carbon (C) content and the 13C enrichment (δ13C signature) of soil organic matter (SOM) with increasing depth in a soil profile under permanent grassland (C3 vegetation) were investigated. The relationship between the total C content and the δ13C signature at different depths in the upper 30 cm of the soil profile could be well fitted by the Rayleigh equation (y = −29.8 − 2.3x, R2 = 0.95, p < 0.001), describing the enrichment in 13C as resulting from isotopic fractionation associated with C mineralization (isotope enrichment factor ε = −2.3‰). Potential C dynamics of SOM in four depth intervals of the profile (0–10, 10–20, 20–30 and 30–40 cm depth) were investigated through an incubation study. The C decomposition rate constants decreased with increasing sampling depth from 0.0479 yr−1 (0–10 cm sampling depth) to 0.0256 yr−1 (30–40 cm sampling depth) and were highly correlated (y = 0.02 + 0.13x, R2 = 0.93, p < 0.05) with the corresponding Δδ13C values (average change of the δ13C signature per depth increment). These results suggest that changes of the δ13C signature of SOM in undisturbed soil profiles under continuous C3 vegetation may serve as an indicator of the variation of SOM quality with increasing depth. Copyright © 2002 John Wiley & Sons, Ltd.

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