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Using the concentration-dependence of respiration arising from glucose addition to estimate in situ concentrations of labile carbon in grassland soil

Rousk, Johannes LU ; Hill, Paul W. and Jones, Davey L. (2014) In Soil Biology & Biochemistry 77. p.81-88
Abstract
In this study, we first determined the low molecular weight dissolved organic carbon (LMW DOC) concentration-dependent kinetics of soil respiration in a temperate grassland soil sampled on successive occasions. We then used the established relationship to estimate in situ LMW DOC concentrations from basal respiration measurements. C-14-labelled glucose was used as a model substrate and was added to soil over a wide range of concentrations (0.05-4000 mu g C g(-1) DW soil; equivalent to ca. 2.5 mu M-200 mM glucose-C). The time-dependent loss of C-14-glucose to (CO2)-C-14 was similar to previous assessments. The Michaelis-Menten parameter V-max varied between 17 (September 2010) and 42 (October 2010) mu g CO2-C g(-1) h(-1) (corresponding to... (More)
In this study, we first determined the low molecular weight dissolved organic carbon (LMW DOC) concentration-dependent kinetics of soil respiration in a temperate grassland soil sampled on successive occasions. We then used the established relationship to estimate in situ LMW DOC concentrations from basal respiration measurements. C-14-labelled glucose was used as a model substrate and was added to soil over a wide range of concentrations (0.05-4000 mu g C g(-1) DW soil; equivalent to ca. 2.5 mu M-200 mM glucose-C). The time-dependent loss of C-14-glucose to (CO2)-C-14 was similar to previous assessments. The Michaelis-Menten parameter V-max varied between 17 (September 2010) and 42 (October 2010) mu g CO2-C g(-1) h(-1) (corresponding to 1.4-3.5 mu mol CO2 g(-1) h(-1)), while K-m varied between 893 (September 2010) and 1990 (October 2010) mu g glucose-C g(-1) (41-92 mM glucose), thus within the span previously reported for soils, albeit in the higher end of the range. However, the estimates were 6 orders-of-magnitude greater than those found in previous studies in natural waters. A possible methodological reason for this difference was an induced multiphasic concentration dependence, biasing K-m and V-max with high concentrations of LMW DOC. By combining the established concentration dependences with measurements of basal respiration, we estimated in situ concentrations of LMW DOC of 131 (October 2010), 112 January 2011) and 270 (September 2010) mu g LMW DOC g(-1), far exceeding the total DOC concentration in the soil (17-20 mu g DOC g(-1) soil), thus invalidating our approach. We propose a way forward, and suggest that although current estimates of LMW DOC cycling need revision, there is evidence for a rapidly cycling pool of LMW DOC, possibly turning over >30 times per day, that warrants further attention. (C) 2014 Elsevier Ltd. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Microbial decomposer community, Soil organic matter degradation, Michaelis-Menten kinetics, Substrate loading rates, Carbon sequestration
in
Soil Biology & Biochemistry
volume
77
pages
81 - 88
publisher
Elsevier
external identifiers
  • wos:000341556600009
  • scopus:84903893939
ISSN
0038-0717
DOI
10.1016/j.soilbio.2014.06.015
project
MICCS - Molecular Interactions Controlling soil Carbon Sequestration
Microbial carbon-use efficiency
Interaction between fungi and bacteria in soil
language
English
LU publication?
yes
id
f25a19ca-5d5c-41a7-b700-32fcf9343650 (old id 4713131)
date added to LUP
2014-11-06 13:45:32
date last changed
2017-02-05 03:46:51
@article{f25a19ca-5d5c-41a7-b700-32fcf9343650,
  abstract     = {In this study, we first determined the low molecular weight dissolved organic carbon (LMW DOC) concentration-dependent kinetics of soil respiration in a temperate grassland soil sampled on successive occasions. We then used the established relationship to estimate in situ LMW DOC concentrations from basal respiration measurements. C-14-labelled glucose was used as a model substrate and was added to soil over a wide range of concentrations (0.05-4000 mu g C g(-1) DW soil; equivalent to ca. 2.5 mu M-200 mM glucose-C). The time-dependent loss of C-14-glucose to (CO2)-C-14 was similar to previous assessments. The Michaelis-Menten parameter V-max varied between 17 (September 2010) and 42 (October 2010) mu g CO2-C g(-1) h(-1) (corresponding to 1.4-3.5 mu mol CO2 g(-1) h(-1)), while K-m varied between 893 (September 2010) and 1990 (October 2010) mu g glucose-C g(-1) (41-92 mM glucose), thus within the span previously reported for soils, albeit in the higher end of the range. However, the estimates were 6 orders-of-magnitude greater than those found in previous studies in natural waters. A possible methodological reason for this difference was an induced multiphasic concentration dependence, biasing K-m and V-max with high concentrations of LMW DOC. By combining the established concentration dependences with measurements of basal respiration, we estimated in situ concentrations of LMW DOC of 131 (October 2010), 112 January 2011) and 270 (September 2010) mu g LMW DOC g(-1), far exceeding the total DOC concentration in the soil (17-20 mu g DOC g(-1) soil), thus invalidating our approach. We propose a way forward, and suggest that although current estimates of LMW DOC cycling need revision, there is evidence for a rapidly cycling pool of LMW DOC, possibly turning over >30 times per day, that warrants further attention. (C) 2014 Elsevier Ltd. All rights reserved.},
  author       = {Rousk, Johannes and Hill, Paul W. and Jones, Davey L.},
  issn         = {0038-0717},
  keyword      = {Microbial decomposer community,Soil organic matter degradation,Michaelis-Menten kinetics,Substrate loading rates,Carbon sequestration},
  language     = {eng},
  pages        = {81--88},
  publisher    = {Elsevier},
  series       = {Soil Biology & Biochemistry},
  title        = {Using the concentration-dependence of respiration arising from glucose addition to estimate in situ concentrations of labile carbon in grassland soil},
  url          = {http://dx.doi.org/10.1016/j.soilbio.2014.06.015},
  volume       = {77},
  year         = {2014},
}