Microcalorimetric Observations of Microbial Activity in Normal and Acidified Soils

Abstract

Microcalorimetric studies of microbial activity were made on normal soil and soils where pH had been lowered ca. 2 units by the addition of dilute sulphuric acid. Sandy field soils were used in all experiments. Cellulose or glucose was added in some series to stimulate microbial activity. For non-amended soil samples the decrease in pH had no significant influence on the microbial activity as judged by the recorded heat effects. In samples which were supplied with extra energy substrate, the heat effects obtained from the controls were significantly larger than those from acidified samples.