ABSTRACT
The soil ecosystem, which harbours a vast, complex and interactive community of soil organisms, is considered as an open system in a steady state. A system is said to be in a steady state when, irrespective of time, the production and consumption of each component, including different microorganisms, are equally balanced. A condition wherein a mature ecosystem resists to change and returns to a steady state if disturbed is termed as homeostasis. Most environments have been reported to differ greatly in microbial species (Slater and Bull, 1978; Bull, 1980). If environmental condi tions are altered due to factors such as change in nutrition, invasion through introduction of new microbial species, additions of xenobiotics like pesti cides, etc., dramatic changes occur in microbial populations. Similarly, a dramatic increase in the population of one species in an ecosystem is pos sible under some specific conditions like the addition of carbon and energy substrates into a system like soil (Alexander, 1971,1977). This abrupt in crease in populations is known as ecological upset or ecological explosion. Marsh (1980) has described the different components responsible for the stability in any given community.
