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Updated: Oct 5, 2025

Assessment of Labile Organic Carbon in Soil Using Sequential Fumigation Incubation Procedures
Published on: October 29, 2016
Volatile and Dissolved Organic Carbon Sources Have Distinct Effects on Microbial Activity, Nitrogen Content, and
Steven G McBride1,2, Ernest D Osburn3,4, Jane M Lucas4,5
1Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, 40546, USA. sgmcbride@uky.edu.
Soil microbes respond differently to carbon sources like dissolved organic carbon and volatile organic compounds, especially under dry conditions. Volatile organic compounds can significantly impact microbial activity and community structure in low-moisture soils.
Area of Science:
- Soil Microbiology
- Biogeochemistry
- Environmental Science
Background:
- Microbial utilization of soil carbon compounds drives biogeochemical cycles and shapes microbial communities.
- Soil carbon substrates include low molecular weight-dissolved organic carbon (LMW-DOC) and volatile organic compounds (VOCs).
- Understanding how different carbon sources affect soil ecosystems under varying moisture is crucial.
Purpose of the Study:
- To compare the effects of LMW-DOC and VOCs on soil chemistry and microbial communities.
- To investigate these effects across a range of soil moisture levels.
Main Methods:
- A microcosm experiment was conducted with five soil moisture levels and five carbon amendment types (control, glucose, oxalate, methanol, α-pinene).
- Microbial activity was assessed via soil respiration.
- Soil organic carbon, total extractable nitrogen, and prokaryotic community composition (via amplicon sequencing) were measured.
Main Results:
- All carbon amendments increased microbial activity; most decreased total extractable nitrogen.
- Specific microbial phyla showed differential responses to carbon amendments (e.g., Proteobacteria increased with glucose and VOCs).
- An interaction between moisture and carbon type was observed: VOCs enhanced microbial activity more than LMW-DOC at low moisture.
Conclusions:
- The type of labile carbon source significantly influences soil microbial diversity and ecosystem functions.
- Volatile organic compounds play a critical role in driving microbial functions and community composition, particularly under low moisture conditions.
- Specific microbial taxa predict soil microbial activity and nitrogen availability.
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