Quantifying charcoal degradation and negative priming of soil organic matter with a radiocarbon-dead tracer

Tilston, E. L., Ascough, P. L. , Garnett, M. H. and Bird, M. I. (2016) Quantifying charcoal degradation and negative priming of soil organic matter with a radiocarbon-dead tracer. Radiocarbon, 58(4), pp. 905-919. (doi: 10.1017/RDC.2016.45)

Abstract

Converting biomass to charcoal produces physical and chemical changes greatly increasing environmental recalcitrance, leading to great interest in the potential of this carbon form as a long-term sequestration strategy for climate change mitigation. Uncertainty remains, however, over the timescale of charcoal’s environmental stability, with estimates varying from decadal to millennial scales. Uncertainty also remains over charcoal’s effect on other aspects of carbon biogeochemical cycling and allied nutrient cycles such as nitrogen. Radiocarbon is a powerful tool to investigate charcoal mineralization due to its sensitivity; here we report the results of a study using 14C-dead charcoal (pMC=0.137±0.002) in organic-rich soil (pMC=99.76±0.46), assessing charcoal degradation over 55 days of incubation. Using this method, we discriminated between decomposition of indigenous soil organic matter (SOM) and charcoal by microorganisms. SOM was the major source of carbon respired from the soil, but there was also a contribution from charcoal carbon mineralization. This contribution was 2.1 and 1.1% on days 27 and 55, respectively. We also observed a negative priming effect due to charcoal additions to soil, where SOM mineralization was repressed by up to 14.1%, presumably arising from physico-chemical interactions between soil and charcoal.

• Item Type: Articles
• Additional Information: Support for 14C measurements within this study was provided through the NERC Radiocarbon Facility NRCF010001 (alloc. 1510.1010). Overall financial support was provided by NERC (NE/F017456/1).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Tilston, Dr Emma and Garnett, Dr Mark and Ascough, Dr Philippa
• Authors: Tilston, E. L., Ascough, P. L., Garnett, M. H., and Bird, M. I.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Radiocarbon
• Publisher: Cambridge University Press
• ISSN: 0033-8222
• ISSN (Online): 1945-5755
• Published Online: 28 July 2016
• Copyright Holders: Copyright © 2016 by the Arizona Board of Regents on behalf of the University of Arizona
• First Published: First published in Radiocarbon 58(4):905-919
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher