In seeking the temperature effects on soil respiration, contributions from plant root activities and bulk soil must be considered separately because their responses to the temperature are likely to be different. Various root-exclusion methods have been used in the field to separately measure the carbon dioxides contributed by root activities and bulk soils. Our objective was to use an automated CO2 measurement system coupled with a root-exclusion method to measure soil CO2 concentrations in rooted and root-excluded soils with a high temporal resolution. A 0.75 by 1.25 m area was isolated from a 6 by 9 m corn plot by burying two layers of plastic film sandwiching a layer of aluminum film to a depth 0.9 m. Six CO2 transmitters, TDR, and thermistors were installed at depths of 10 to 60 cm with an interval of 10 cm inside and outside the isolated area, and two more CO2 transmitters near the soil surface. No corn was planted inside the isolated area and outside corn roots could not extended into the isolated area. The measured CO2 concentrations in root-excluded soils were consistently lower than in rooted soil at all measured depths over the growing season. High temporal resolutions of soil CO2, temperature, and moisture over depth permit the computation of CO2 production over depths of both rooted and root-excluded soils. The difference between CO2 productions of rooted and root-excluded soil can be considered as contribution of corn roots.
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