Importance of microbial soil organic matter processing in dissolved organic carbon production

Ashish Malik (Corresponding Author), Gerd Gleixner*

*Corresponding author for this work

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

Soil dissolved organic carbon (DOC) sources and its seasonal dynamics are poorly known. We aimed to determine the contribution of plant and soil organic matter (SOM) to size classes of DOC in a field experiment with C3 to C4 vegetation change on two soil types through different seasons. Stable isotope ratios of DOC size classes were measured using size exclusion chromatography (SEC) coupled online to liquid chromatography-isotope ratio mass spectrometry (LC-IRMS). SEC resolved DOC into three size classes: very high molecular weight/vHMW (> 10 kDa), high molecular weight/HMW (0.4-10 kDa), and low molecular weight/LMW (< 0.4 kDa). HMW DOC was most abundant in all seasons, soil types, and depths. In contrast, vHMW DOC was only seen postsnowmelt in upper 20 cm and was mainly (87 ± 9%) plant-derived. Through all seasons, HMW and LMW DOC had less than 30% recent plant contribution. Similar size range and source of DOC size classes and soil chloroform fumigation extracts suggest microbial origin of DOC. Thus, microbial SOM recycling is an important process in DOC production. We suggest that DOC molecules get partitioned manifold between soil solution and the mineral matrix (chromatography), thereby getting constantly decomposed, altered, or produced anew by soil microorganisms (reactive transport).

Original languageEnglish
Pages (from-to)139-148
Number of pages10
JournalFEMS Microbiology Ecology
Volume86
Issue number1
DOIs
Publication statusPublished - 1 Oct 2013

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Keywords

  • C
  • C3-C4 vegetation change
  • DOC size classes
  • LC-IRMS
  • Soil microbial biomass

ASJC Scopus subject areas

  • Ecology
  • Applied Microbiology and Biotechnology
  • Microbiology

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