Factors influencing the calorespirometric ratios of soil microbial metabolism

Abstract Calorespirometric ratio of metabolism connects the metabolic activity with the nature of the substrate and metabolic pathways being used by cells and microorganisms. Calorespirometric ratios have been determined for many living systems including animals, plants, plant and animal cells, and many different microorganisms, but application to soil is very recent. Calorespirometric ratios for soils are obtained by simultaneous calorimetric measurements of heat and CO 2 rates from biodegradation of soil organic matter. The purpose here is to gain a better understanding of the factors influencing the value of the calorespirometric ratio in soil, i.e. changes in the composition of the soil organic matter, soil moisture, soil particle size, and soil management (e.g. conversion of pasture to forest). Results indicate that calorespirometric ratios are sensitive to moisture, soil size fraction, and the source and age of soil organic matter.