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This article in SSSAJ

  1. Vol. 68 No. 2, p. 514-518
     
    Received: May 26, 2003


    * Corresponding author(s): mart0166@umn.edu
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doi:10.2136/sssaj2004.5140

A CARBON DIOXIDE FLUX GENERATOR FOR TESTING INFRARED GAS ANALYZER-BASED SOIL RESPIRATION SYSTEMS

  1. Jonathan G. Martin *a,
  2. Paul V. Bolstada and
  3. John M. Normanb
  1. a Dep. of Forest Resources, 115 Green Hall, Univ. of Minnesota, 1530 Cleveland Ave. N., St. Paul, MN 55108
    b Dep. of Soil Science, Univ. of Wisconsin-Madison, 1525 Observatory Dr., Madison, WI 53706

Abstract

An artificial flux generation device was developed to test the accuracy of a closed-dynamic soil respiration system (LICOR 6400). The device consisted of an enclosed reservoir with a porous top; the reservoir contained a volume of CO2 enriched air, which was monitored by an infrared gas analyzer (IRGA). When the internal CO2 concentration within the reservoir was elevated, diffusion rates through the porous medium were measured by recording changes in CO2 concentration within the reservoir. This diffusion-based artificial flux mimics natural soil respiration, and allows an independent verification of the accuracy of soil respiration measurement systems. We tested a LI-COR 6400 portable photosynthesis system fitted with a 6400-09 soil CO2 flux chamber. On average, this system overestimated high flux rates by 2 to 4% and underestimated low flux rates by 4 to 20% over five independent trials. Soil respiration appeared to be sensitive to boundary layer mixing, and ambient CO2 concentrations.

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Copyright © 2004. Soil Science SocietySoil Science Society of America