Annual Cycles of Carbon Dioxide Level in Soil Air
1983
Buyanovsky, G. A. | Wagner, G. H.
The CO₂ concentration of the gaseous phase of a silt loam soil (Udollic Ochraqualf) was studied under cultivation of wheat (Triticum aestivum), corn (Zea mays L.), and soybeans (Glycine max L. Merr.) over a 2-year period. Disposable chromatographic tubes for direct field measurements of CO₂ in soil air were used. Dynamics of CO₂ in the soil air were observed to be conditioned by both biological and abiotic factors. Under wheat, periods of highest CO₂ concentration (6–8%) corresponded to times of intensive decomposition of plant residue within the soil profile. Under corn and soybeans, highest CO₂ concentrations were related to the periods of intensive plant growth. Soil moisture and soil temperature combined, were found to be responsible for just > 50% of CO₂ fluctuations. The influence of water tension on CO₂ in the soil atmosphere was more significant (r² = 0.83) if data were restricted to that where temperature was 20 ± 2°C, and in transformations of the two parameters were used. The ln-to-ln dependence was linear within the limits from field capacity to wilting point. Under conditions of optimum soil water content, ln of CO₂ concentration increased linearly with ln of soil temperature within the limits of 10 to 20°C.
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