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Title: MEASUREMENT OF SOIL RESPIRATION IN SITU: CHAMBER TECHNIQUES.

Author
item ROCHETTE, PHILIPPE - AG/AG FOOD CANADA
item HUCHINSON, GORDON - ARS RETIRED

Submitted to: American Society of Agronomy Monograph Series
Publication Type: Popular Publication
Publication Acceptance Date: 3/1/2004
Publication Date: 8/8/2005
Citation: Rochette, P., Huchinson, G.L. 2005. Measurement of soil respiration in situ: chamber techniques. American Society of Agronomy Monograph Series No. 47. IN Micrometeorology in Agricultural Systems. pp. 247-286.

Interpretive Summary: Chambers are not exempt from methodological problems. In this book chapter, we review known sources of chamber-induced errors in estimates. Despite the multiplicity and diversity of potential errors, however, we believe their overall impact on chamber-based estimates will be minimal if the information we summarize is used to select the chamber design best suited to the research objective and to establish the optimum protocol to be followed before, during, and after the measurement period.

Technical Abstract: Chamber methods depend exclusively on headspace gas concentration measurements or determining the unused capacity of a known chemical trap, they provide only an indirect measure of the CO2 flux across the soil surface, which is in turn equal to the soil respiration rate only under steady-state conditions. Thus, the challenge when using chamber techniques is to minimize preturbations by the chamber of not only the underlying rates of root and microbial respiration, but also the transport and emission phenomena that determine what fraction of total CO2 production reaches the headspace of the chamber during its period of deployment. The princiapal factors influencing chamber performance include soil and air temperature, CO2 concentration gradients, pressure fluctuations, soil and air moisture, site disturbance, leakage, and air mixing regime.