Some observations on the microbial activity in remoistened air-dried soils

Abstract

Comparative studies on the respiration of four air-dried and fresh soils show that in all cases a higher level of metabolic activity is attained in the air-dried soils following remoistening. The degree by which metabolic activity increases in remoistened air-dried soils varies directly with the concentrations of free amino acids and other nitrogenous materials released by the air drying process. No appreciable gas exchange was noted through chemical action alone and it is felt that the increased respiration of air-dried samples over fresh soils is due mainly to biological activity. Quantitative studies of the bacterial flora of air-dried soils indicate a short lag period followed by a phase of logarithmic increase during the early stages following remoistening. These results are discussed in terms of the bacterial population existing after air drying and its relationship to the high respiratory activity observed.