Author(s)

Natalya Smirnova, Michael Scott Demyan, Frank Rasche, Georg Cadisch, Torsten Müller

Institute of Crop Science (340i), University of Hohenheim, Stuttgart, Germany.
Institute of Plant Production and Agroecology in the Tropics and Subtropics (380a), University of Hohenheim, Stuttgart, Germany.

Measurements of carbon dioxide (CO₂)-evolution from soils are important in evaluating biomass and activity of soil microorganisms, as well as decomposition of soil organic matter. The Respicond VI is a fully computerized system allowing continuous measurement of CO₂ evolution in short- and long-term soil incubation experiments in up to 96 incubation vessels. The measurement of CO₂ evolution is based on the absorption of CO₂ by an electrolyte (KOH solution) producing a change in the cell conductance measured using two electrodes. In this study, the Respicond VI was recalibrated yielding 174.5 mg CO₂ as constant A expressing the theoretical maximum amount of CO₂ absorbed in 10 ml 0.5 M KOH. This value of A corresponds to 34.9 mg CO₂ ml^-1 1 M KOH. The constant A does neither depend on the investigated incubation temperatures (5°C - 25°C) nor on the concentrations of the KOH solutions (0.5, 0.1, 0.05 M KOH). To eliminate any influence of changing incubation temperatures, either induced by uncertainties in temperature control or as a part of the experimental setup, on the conductance of KOH solution, a correction procedure was developed using a factor calculated from changing conductance of KOH solutions in incubation vessels without soil.

Respirometer, Soil Respiration, Carbon Dioxide, Incubation

Smirnova, N. , Demyan, M. , Rasche, F. , Cadisch, G. and Müller, T. (2014) Calibration of CO₂ Trapping in Alkaline Solutions during Soil Incubation at Varying Temperatures Using a Respicond VI. Open Journal of Soil Science, 4, 161-167. doi: 10.4236/ojss.2014.45019.