Effect of Freezing of Soil on Denitrification

Abstract

A MAJOR difficulty in investigations of biological processes in soils is the preservation of the biological activity from the time of collection of the soil sample in the field until commencement of the laboratory investigation. Freezing of soil samples could feasibly be the means of preserving this biological activity since microbial growth ceases and enzymatic actions are retarded at low temperatures. Gasser¹ has suggested that the nitrifying activity in freshly sampled soil can be retained in this way. Since then, other workers have shown that when soils frozen at temperatures of −78° C and −190° C are thawed and incubated, increased nitrogen mineralization and aerobic respiration result^2,3.