Calorimetric determination of metabolic heat, CO2 rates and the calorespirometric ratio of soil basal metabolism

Characterizing soil metabolism requires measurement of the CO2 production rate or metabolic heat rate. While a single rate provides information on how rapidly substrates are being metabolized, the ratio of metabolic heat rate to CO2 production rate provides information on the nature of the substrates and the biochemical reactions taking place in the soil. Methodology to simultaneously monitor metabolic heat and CO2 production rates of soil basal metabolism by calorimetry is described. Plots of metabolic heat and CO2 rates against time for thirteen soil samples collected along a transect in northern Spain are presented. The ratio of metabolic heat rate to CO2 production rate showed degradation of carbohydrates through aerobic respiration in some of the samples and informed about the nature of the organic matter being degraded in all of them.

Research Highlights
► Heat and CO2 rates are well known indexes of soil basal metabolism.
► A method is provided for easy concomitant determinations of both indexes.
► Heat to CO2 rate ratio can be calculated by this procedure.
► Application to soil provides information about OM degradability.