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A calibration system for soil carbon dioxide efflux measurement chambers: Description and application

Widen, B and Lindroth, Anders LU (2003) In Soil Science Society of America Journal 67(1). p.327-334
Abstract
Comparisons have revealed large discrepancies among the many methods for measuring soil CO2 efflux indicating the need for an absolute calibration of methods. This study presents a calibration system, constructed to imitate an area of soil, and its application to two different chamber systems for the measurement Of Soil CO2 efflux: one open and one closed dynamic. Air rich in CO2 was allowed to diffuse through a layer of sand on top of a box of known volume. By measuring the decrease in CO2 Concentration inside the box, the exact CO2 efflux could be calculated. The CO2 efflux rates measured by the chambers could then be compared with the efflux rates calculated from the box. The error of the closed-chamber system ranged from an... (More)
Comparisons have revealed large discrepancies among the many methods for measuring soil CO2 efflux indicating the need for an absolute calibration of methods. This study presents a calibration system, constructed to imitate an area of soil, and its application to two different chamber systems for the measurement Of Soil CO2 efflux: one open and one closed dynamic. Air rich in CO2 was allowed to diffuse through a layer of sand on top of a box of known volume. By measuring the decrease in CO2 Concentration inside the box, the exact CO2 efflux could be calculated. The CO2 efflux rates measured by the chambers could then be compared with the efflux rates calculated from the box. The error of the closed-chamber system ranged from an underestimate of 19% to an overestimate of 21%. The errors were most likely caused by a combination of underestimated chamber volume, causing an underestimation Of CO2 efflux, and turbulence within the chamber, which increased the flax by disturbing the boundary layer above the surface. The open-chamber system always overestimated the CO2 efflux. Disturbing the boundary layer alone was believed to cause a 17% increase in efflux. Increasing negative pressure difference caused a mass flow of CO2-rich air into the chamber. At a pressure difference of -0.15 Pa, the error was 11 to 40%, depending on air-filled soil volume. Accordingly, soil-water content, a parameter to which soil CO2 efflux is often related, was found to substantially affect the measurements made by both tested systems. These results point to the need of calibrating systems used for measuring soil CO2 efflux is measured against a known flux, to elucidate the limits and applicability of each system. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Soil Science Society of America Journal
volume
67
issue
1
pages
327 - 334
publisher
Soil Science Society of Americ
external identifiers
  • wos:000181886100037
  • scopus:0037241316
ISSN
0361-5995
language
English
LU publication?
yes
id
7825468a-1295-4f2e-a864-f13a9c2ad3c9 (old id 315045)
alternative location
http://soil.scijournals.org/cgi/content/abstract/67/1/327
date added to LUP
2007-09-24 08:35:01
date last changed
2018-05-29 11:16:32
@article{7825468a-1295-4f2e-a864-f13a9c2ad3c9,
  abstract     = {Comparisons have revealed large discrepancies among the many methods for measuring soil CO2 efflux indicating the need for an absolute calibration of methods. This study presents a calibration system, constructed to imitate an area of soil, and its application to two different chamber systems for the measurement Of Soil CO2 efflux: one open and one closed dynamic. Air rich in CO2 was allowed to diffuse through a layer of sand on top of a box of known volume. By measuring the decrease in CO2 Concentration inside the box, the exact CO2 efflux could be calculated. The CO2 efflux rates measured by the chambers could then be compared with the efflux rates calculated from the box. The error of the closed-chamber system ranged from an underestimate of 19% to an overestimate of 21%. The errors were most likely caused by a combination of underestimated chamber volume, causing an underestimation Of CO2 efflux, and turbulence within the chamber, which increased the flax by disturbing the boundary layer above the surface. The open-chamber system always overestimated the CO2 efflux. Disturbing the boundary layer alone was believed to cause a 17% increase in efflux. Increasing negative pressure difference caused a mass flow of CO2-rich air into the chamber. At a pressure difference of -0.15 Pa, the error was 11 to 40%, depending on air-filled soil volume. Accordingly, soil-water content, a parameter to which soil CO2 efflux is often related, was found to substantially affect the measurements made by both tested systems. These results point to the need of calibrating systems used for measuring soil CO2 efflux is measured against a known flux, to elucidate the limits and applicability of each system.},
  author       = {Widen, B and Lindroth, Anders},
  issn         = {0361-5995},
  language     = {eng},
  number       = {1},
  pages        = {327--334},
  publisher    = {Soil Science Society of Americ},
  series       = {Soil Science Society of America Journal},
  title        = {A calibration system for soil carbon dioxide efflux measurement chambers: Description and application},
  volume       = {67},
  year         = {2003},
}