COMPARATIVE-STUDY OF THE MICROBIAL ACTIVITY IN DIFFERENT SOILS BY THEMICROCALORIMETRIC METHOD

Microcalorimetry was applied to the study of the microbial activity of four soils with different percentages of organic matter. The qualitat ive study of the heat flow rate-time curves, recorded from soil sample s amended with glucose, showed remarkable differences in the soil micr obial activity. In order to show results in a more quantitative way, t he total heat evolution, Q(tot), the total heat evolution of soil samp les amended with glucose, Q(tot(glc)), and the values of peak time and microbial growth rate constant, mu, were calculated from the heat flo w rate-time curves recorded from all samples. Values of peak time incr eased with decreased microbial density and a positive correlation betw een total heat evolution, Q(tot), and percentage of organic matter, wa s found. Microcalorimetry appears as a suitable technique to carry out both qualitative and quantitative comparative studies of microbial ac tivity in soils. (C) 1997 Elsevier Science B.V.