ABSTRACT
Microbial communities play an important role in nutrient cycling by the process of mineralization and decomposition of organic waste material, which are released into the soil as nutrients that are essential for plant growth. These communities can influence nutrient availability under the processes of solubilisation, chelation, and oxidation/reduction. In addition, soil microorganisms may affect nutrient uptake and plant growth by the release of growth stimulating or inhibiting substances that influence root physiology and root architecture in the rhizosphere zone. Microorganisms decompose organic matter, detoxify the toxic substance, fixing the nitrogen, transformation of nitrogen, phosphorous, potassium and other secondary and micro nutrients are the major biochemical activities performed by microbes in soil. This chapter explains most important factors that can influence the population dynamics of microbial communities. Agriculturally important microorganisms consist of phenomenal diversity which includes plant growth promoting N-fi Cyanobacteria, Rhizobacteria, Mycorrhiza, plant disease suppressive benefi bacteria, stress tolerance entophytes, and bio-degrading microbes.
