Unambiguous evidence of old soil carbon in grass biosilica particles

Paul E. Reyerson, Anne Alexandre, Araks Harutyunyan, Remi Corbineau, Hector A.Martinez De La Torre, Franz Badeck, Luigi Cattivelli, Guaciara M. Santos

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


Plant biosilica particles (phytoliths) contain small amounts of carbon called phytC. Based on the assumptions that phytC is of photosynthetic origin and a closed system, claims were recently made that phytoliths from several agriculturally important monocotyledonous species play a significant role in atmospheric CO2 sequestration. However, anomalous phytC radiocarbon (14C) dates suggested contributions from a non-photosynthetic source to phytC. Here we address this non-photosynthetic source hypothesis using comparative isotopic measurements (14C and δ 13C) of phytC, plant tissues, atmospheric CO2, and soil organic matter. State-of-the-art methods assured phytolith purity, while sequential stepwise-combustion revealed complex chemical-thermal decomposability properties of phytC. Although photosynthesis is the main source of carbon in plant tissue, it was found that phytC is partially derived from soil carbon that can be several thousand years old. The fact that phytC is not uniquely constituted of photosynthetic C limits the usefulness of phytC either as a dating tool or as a significant sink of atmospheric CO2. It additionally calls for further experiments to investigate how SOM-derived C is accessible to roots and accumulates in plant biosilica, for a better understanding of the mechanistic processes underlying the silicon biomineralization process in higher plants.

Original languageEnglish (US)
Pages (from-to)1269-1286
Number of pages18
Issue number4
StatePublished - Mar 1 2016

Bibliographical note

Funding Information:
The authors gratefully acknowledge the support of the US National Science Foundation (DEB-1144888 to GMS), the French FIR 2010 (Aix-Marseille Université), ECCOREV 2011, AIR Archéométrie 2011(CNRS) and Labex OT-Med 2013. PER wishes to thank J. A. Mason (University of Wisconsin-Madison) and the National Lacustrine Core Facility (University of Minnesota) for lab space usage. GMS thanks M. J. Ottman, B. Kimball, S. W. Leavitt, E. Pendall, P. Pinter, G. Hendrey, H. L. Cho and R. Rauschkolb for providing the archived Maricopa FACE samples. Financial support provided by the Durum experiment via the "Fondazione in rete per la ricerca agroalimentare" with the AGER program: agroalimentare e ricerca is gratefully acknowledged. We thank J. Southon for help with the

Funding Information:

Funding Information:
C-AMS analyses, and C. Czimczik and M. Lupasco for technical support with the CO2 flux measurements, help in interpreting the data, and suggestions and comments on an early version of this paper. We would like to thank X. Xu for the stable isotope analysis and technical support for CO

Funding Information:

Funding Information:
-air cryogenic extraction, and Q. Lin and the Laboratory for Electron and X-ray Instrumentation (LEXI) at UC Irvine for access to lab space and assistance with X-ray analytical techniques. We also thank S. Fahrni for providing the inorganic fertilizer used in the control planter, and K. Gallagher for her efforts on the estimates of percent carbon of some amendments. A. Alexandre thanks J. Balesdent (CEREGE) for helpful discussion on root absorption of molecular C. The authors also wish to extend their thanks to the Editor Roland Bol and the three anonymous reviewers for the constructive comments.

Publisher Copyright:
© 2016 Author(s).

Copyright 2017 Elsevier B.V., All rights reserved.


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