Loss and gain of carbon during char degradation

Bird, Michael I., McBeath, Anna V., Ascough, Philippa L., Levchenko, Vladimir A., Wurster, Christopher M., Munksgaard, Niels C., Smernik, Ronald J., and Williams, Alan (2017) Loss and gain of carbon during char degradation. Soil Biology & Biochemistry, 106. pp. 80-89.

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Abstract

We report results of a study examining controls on the degradation of chars produced at 300, 400 and 500 °C from radiocarbon-free wood, deployed for three years in a humid tropical rainforest soil in north Queensland, Australia. The chars were subjected to four treatments (i) no litter (ii) covered by leaf litter, (iii) covered by limestone chips to alter local pH, and (iv) covered by limestone chips mixed with leaf litter. Radiocarbon, stable isotope and proximate analyses indicate significant ingress of exogenous (environmental) carbon and mineral material, strongly correlated with loss of indigenous (char) carbon from the samples. While indigenous carbon losses over three years were generally <8% for the char produced at 500 °C char under any treatment, chars formed at lower temperatures lost 5–22% of indigenous carbon accompanied by ingress of up to 7.5% modern exogenous carbon. The data provide clear evidence of a direct link between the ingress of exogenous carbon, likely at least partly due to microbial colonization, and the extent of char decomposition. Failure to account for the ingress of exogenous carbon will lead to a significant under-estimate of the rate of char degradation.

Item ID: 46768
Item Type: Article (Refereed Research - C1)
Keywords: biochar, radiocarbon, carbon-isotope, degradation, carbon sequestration
ISSN: 1879-3428
Funders: Australian Research Council (ARC), Australian Institute of Nuclear Science and Engineering (AINSE), National Environmental Research Council (NERC)
Projects and Grants: ARC Federation Fellowship FF0883221, AINSE grant ALNGRA10061 , NERC standard grant number NE/F017456/1
Date Deposited: 09 Jan 2017 22:15
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0503 Soil Sciences > 050301 Carbon Sequestration Science @ 100%
SEO Codes: 96 ENVIRONMENT > 9603 Climate and Climate Change > 960302 Climate Change Mitigation Strategies @ 50%
96 ENVIRONMENT > 9614 Soils > 961403 Forest and Woodlands Soils @ 50%
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