THE EFFECT OF SOIL-MOISTURE ON SOIL MICROBIAL ACTIVITY STUDIED BY MICROCALORIMETRY

Microcalorimetry has been used to study the effect of moisture on soil microbial activity. Different moisture regimes produce changes on hea t flow rate-time curves recorded for soil samples, affecting also cert ain parameters, such as the total heat evolution Q(tot), the microbial growth rate constant mu and growth yield Y, which are calculated by t he microcalorimetric method. A positive correlation was found between the percentage humidity, the total heat evolution and the microbial gr owth rate constant. The values of these parameters decrease with the d ryness of the soil. Field capacity moisture appears to be the optimum moisture level for soil microbial activity.