Decomposition of added and native organic carbon from physically separated fractions of diverse soils

Sindhu Jagadamma, J. Megan Steinweg, Melanie A. Mayes, Gangsheng Wang, Wilfred M. Post

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25 Scopus citations

Abstract

There have been increasing efforts to understand the dynamics of organic carbon (OC) associated with measurable fractions of bulk soil. We compared the decomposition of native OC (native C) with that of an added substrate (glucose) on physically separated fractions of a diverse suite of soils. Five soil orders were selected from four contrasting climate zones (Mollisol from temperate, Ultisol and Oxisol from tropics, Andisol from sub-arctic, and Gelisol from arctic region). Soils from the A horizon were fractionated into particulate OC (POC) and mineral-associated OC (MOC) by a size-based method. Fractions were incubated at 20 °C and 50 % water-holding capacity in the dark after the addition of unlabeled d-glucose (0.4 mg C g-1 fraction) and U-14C glucose (296 Bq g-1 fraction). Respiration of glucose 14C indicated 64 to 84 % of added glucose 14C which was respired from POC and 62 to 70 % from MOC within 150 days of incubation, with more than half of the cumulative respiration occurring within 4 days. Native C respiration varied widely across fractions: 12 to 46 % of native C was respired from POC and 3 to 10 % was respired from MOC fractions. This suggested that native C was more stabilized on the MOC than on the POC, but respiration from the added glucose was generally similar for MOC and POC fractions. Our study suggests a fundamental difference between the behavior of freshly added C and native C from MOC and POC fractions of soils.

Original languageEnglish
Pages (from-to)613-621
Number of pages9
JournalBiology and Fertility of Soils
Volume50
Issue number4
DOIs
StatePublished - May 2014

Funding

Acknowledgments This research was funded in part by the Laboratory Directed Research and Development (LDRD) Program of the Oak Ridge National Laboratory (ORNL), and by the U.S. Department of Energy Biological and Environmental Research program. ORNL is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725. We thank Stan Wullschleger, Anna Wagner, Julie Jastrow, Yuri Zinn, Guðrún Gísladóttir and Ann Russell for providing soil samples, and Chad Covert, Daniel Wade and Jana Phillips for help with laboratory analyses. Collection and processing of soil samples from Brazil was supported by CNPq. The Costa Rican soils were collected as part of work supported by US National Science Foundation Grants DEB 0236502 and 0703561.

FundersFunder number
U.S. Department of Energy Biological and Environmental Research program
National Science Foundation0703561, DEB 0236502
U.S. Department of EnergyDE-AC05-00OR22725
Oak Ridge National Laboratory
Laboratory Directed Research and Development
Conselho Nacional de Desenvolvimento Científico e Tecnológico

    Keywords

    • Glucose
    • Mineral-associated organic carbon
    • Native organic carbon
    • Particulate organic carbon
    • Respiration

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