Biochemical properties and biodegradation of dissolved organic matter from soils

Susan R. Bowen, Edward G. Gregorich, David W. Hopkins

Research output: Contribution to journalArticlepeer-review

42 Citations (Scopus)


Various biologically mediated processes are involved in the turnover of dissolved organic matter (DOM) in soil; however, relatively little is known about the dynamics of either the microbial community or the individual classes of organic molecules during the decomposition of DOM. We examined the net loss of DOC, the mineralisation of C to CO2 and the degradation of DOC from six different soils by soil microorganisms. We also quantified the changes in the concentrations of protein, carbohydrate and amino acid C during microbial biodegradation. Over a 70-day incubation period at 20°C, the mineralisation of DOC to CO2 was described by a double exponential model with a labile pool (half-life, 3-8 days) and a stable pool (half-life, 0.4-6 years). However, in nearly all cases, the mass loss of DOC exceeded the C released as CO2 with significant deviations from the double exponential model. Comparison of mass DOC loss, CO2 production and microbial cell counts, determined by epifluorescence microscopy, showed that a proportion of the lost DOC mass could be accounted for by microbial assimilation. Carbohydrate and protein C concentrations fluctuated throughout the incubation with a net change of between 3 to 13 and -30 to 22.4% initial DOC, respectively. No amino acid C was detected during the incubation period (level of detection, 0.01 mg C l-1).

Original languageEnglish
Pages (from-to)733-742
Number of pages10
JournalBiology and Fertility of Soils
Issue number7
Publication statusPrint publication - 20 Jun 2009
Externally publishedYes

Bibliographical note

Funding Information:
Acknowledgements We are grateful to the University of Stirling and the UK Biotechnology and Biological Sciences Research Council for supporting this work.

Copyright 2009 Elsevier B.V., All rights reserved.


  • Decomposition dynamics
  • Dissolved organic carbon
  • Dissolved organic matter
  • DOC
  • DOM
  • Microbial assimilation
  • Microbial decomposition
  • Soil water


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