Investigations on “Sickness” in Soil: I. Sewage “Sickness”

Abstract

The experiments of Russell and Hutchinson¹ have shown that the micro-organic population of ordinary soils is not working at a maximum efficiency; there exists a biological factor, provisionally identified with the soil protozoa, detrimental to bacteria and limiting their numbers and activities. It follows that any change in the conditions of the soil that is more favourable to the harmful organisms than to the bacteria will disturb the normal equilibrium between these two sets of organisms and lead to a relative reduction in bacterial numbers and activity. We shall therefore expect to find that causes not in themselves harmful to bacteria may bring about a reduction of bacteria through favouring the development of the detrimental factor.