APPLICATION OF THE WARBURG RESPIROMETER IN STUDYING RESPIRATORY ACTIVITY IN SOIL

An investigation was made into the feasibility of using the Warburg respirometer to study microbial respiration daily in soil for periods of 1 or more weeks, at levels of temperature and moisture normally occurring in the field. Problems arising from such prolonged continuous operation of the respirometers were overcome; and the method, applied to remoistened air-dried soil, yielded data closely fitting a straight line when log rate of oxygen uptake was plotted against log time (i.e. a parabolic function). The introduction of chemical inhibitors or heat treatment disturbed this linear relationship initially, though it reappeared in many instances, and its reappearance seemed to indicate the resumption of normal microbial activity. Since the parabolic function has no recognizable physiological significance in this application, an hypothesis assuming the simultaneous utilization of substrates of different availability is proposed and discussed.