Method for Simultaneous Measurement of Radioactive and Inactive CO(2) Evolved from Soil Samples During Incubation with Labeled Substrates.

An apparatus is described which allows the simultaneous, continuous, and highly sensitive analysis of inactive and radioactive CO(2) evolved from C-supplemented soils or other materials. The apparatus consists of a control unit, a commercially available conductometric CO(2) analyzer, and fraction collector. A number of model experiments were conducted to demonstrate the potentials of the apparatus. These included analysis of the time course of priming action, when C-glucose was added to soil, separation of CO(2) respiration peaks caused by simultaneous degradation of radioactive and inactive soil supplements, and study of the effects of a fungicide, Benomyl, on degradation of C-labeled glucose. In the last experiment, partial degradation of the fungicide could also be followed.