FATE AND ACTIVITY OF MICROORGANISMS INTRODUCED INTO SOIL

Introduced microorganisms are potentially powerful agents for manipula tion of processes and/or components in soil. Fields of application inc lude enhancement of crop growth, protection of crops against plant-pat hogenic organisms, stimulation of biodegradation of xenobiotic compoun ds (bioaugmentation), and improvement of soil structure. Inoculation o f soils has already been applied for decades, but it has often yielded inconsistent ar disappointing results. This is caused mainly by a com monly observed rapid decline in inoculant population activity followin g introduction into soil, i.e., a decline of the numbers of inoculant cells and/or a decline of the (average) activity per cell. in this rev iew, we discuss the available information on the effects of key factor s that determine the fare and activity of microorganisms introduced in to soil, with emphasis on bacteria. The factors addressed include the physiological status of the inoculant cells, the biotic and abiotic in teractions in soil, soil properties, and substrate availability. Final ly, we address the possibilities available to effectively manipulate t he fate and activity of introduced microorganisms in relation to the m ain areas of their application.