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Procedure for determining the biodegradation of radiolabeled substrates in a calcareous soil.

Ström, Lena LU ; Godbold, D L and Jones, D L (2001) In Soil Science Society of America Journal 65(2). p.347-351
Abstract
Calcareous soils are frequently typified by a low availability of plant nutrients due to poor solubility of these elements at high pH. Calcicole plants have recently been shown to release organic acids in response to the nutrient deficient conditions prevailing in these soils. It has been speculated, however, that the efficiency of this nutrient mobilization mechanism may be significantly reduced by microbial degradation of the organic acids. In conventional methods, root exudate degradation is typically determined by the addition of 14C-radiolabeled substrates to soil and subsequent tracking of their fate with time by trapping evolved 14CO2 in a strong alkali trap. However, in calcareous soils, 14CO2 and H214CO3 produced by microbial... (More)
Calcareous soils are frequently typified by a low availability of plant nutrients due to poor solubility of these elements at high pH. Calcicole plants have recently been shown to release organic acids in response to the nutrient deficient conditions prevailing in these soils. It has been speculated, however, that the efficiency of this nutrient mobilization mechanism may be significantly reduced by microbial degradation of the organic acids. In conventional methods, root exudate degradation is typically determined by the addition of 14C-radiolabeled substrates to soil and subsequent tracking of their fate with time by trapping evolved 14CO2 in a strong alkali trap. However, in calcareous soils, 14CO2 and H214CO3 produced by microbial decomposition may become trapped as Ca(H14CO3)2. The aim of this study was to develop and validate an experimental procedure for the accurate quantification of 14C-labeled substrate degradation rates in calcareous soils. Conventional methods for determining 14C-labeled substrate decomposition rates in calcareous soils are inaccurate due to incomplete recovery of 14CO2. Up to 49% of the 14CO2 produced during microbial degradation of 14C-labeled organic acids (malate, oxalate, citrate) was trapped as carbonate in this calcareous soil (pH 7.58). For an acid soil (pH 4.32) no detectable amount of 14CO2 was trapped. We describe a simple, accurate, and reliable method, which includes a postincubation HCl addition, for the accurate determination of 14CO2-evolution and substrate degradation in calcareous soils. (Less)
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author
organization
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type
Contribution to journal
publication status
published
subject
in
Soil Science Society of America Journal
volume
65
issue
2
pages
347 - 351
publisher
Soil Science Society of Americ
external identifiers
  • scopus:0035034947
ISSN
0361-5995
language
English
LU publication?
yes
id
5e3f45fd-0303-4ad2-b4b5-2678e5829205 (old id 620243)
date added to LUP
2007-12-17 13:36:24
date last changed
2017-01-01 07:50:26
@article{5e3f45fd-0303-4ad2-b4b5-2678e5829205,
  abstract     = {Calcareous soils are frequently typified by a low availability of plant nutrients due to poor solubility of these elements at high pH. Calcicole plants have recently been shown to release organic acids in response to the nutrient deficient conditions prevailing in these soils. It has been speculated, however, that the efficiency of this nutrient mobilization mechanism may be significantly reduced by microbial degradation of the organic acids. In conventional methods, root exudate degradation is typically determined by the addition of 14C-radiolabeled substrates to soil and subsequent tracking of their fate with time by trapping evolved 14CO2 in a strong alkali trap. However, in calcareous soils, 14CO2 and H214CO3 produced by microbial decomposition may become trapped as Ca(H14CO3)2. The aim of this study was to develop and validate an experimental procedure for the accurate quantification of 14C-labeled substrate degradation rates in calcareous soils. Conventional methods for determining 14C-labeled substrate decomposition rates in calcareous soils are inaccurate due to incomplete recovery of 14CO2. Up to 49% of the 14CO2 produced during microbial degradation of 14C-labeled organic acids (malate, oxalate, citrate) was trapped as carbonate in this calcareous soil (pH 7.58). For an acid soil (pH 4.32) no detectable amount of 14CO2 was trapped. We describe a simple, accurate, and reliable method, which includes a postincubation HCl addition, for the accurate determination of 14CO2-evolution and substrate degradation in calcareous soils.},
  author       = {Ström, Lena and Godbold, D L and Jones, D L},
  issn         = {0361-5995},
  language     = {eng},
  number       = {2},
  pages        = {347--351},
  publisher    = {Soil Science Society of Americ},
  series       = {Soil Science Society of America Journal},
  title        = {Procedure for determining the biodegradation of radiolabeled substrates in a calcareous soil.},
  volume       = {65},
  year         = {2001},
}