Role Of Microorganisms In Nutrient Mobilization And Soil Health - A Review

Microorganisms represent the largest and most diverse biotic group in soil, with an estimate of one million to one billion microorganisms per one gram of agricultural top soil. Soil health is defined as the capacity of soil to function as a vital living system, by recognizing that it contains biological elements that are key to ecosystem function within land use boundaries. In the context of agriculture, it may refer to its ability to sustain productivity. Microorganisms possess the ability to give an integrated measure of soil health, an aspect that cannot be obtained with physical/chemical measures and/or analyses of diversity of higher organisms. Microorganisms are key players in the cycling of nitrogen, sulfur and phosphorus, and the decomposition of organic residues. They affect nutrient and carbon cycling on a global scale. Production of extra-cellular polysaccharides and other cellular debris by microorganisms help in maintaining soil structure as well as soil health. Thereby, they also affect water holding capacity, infiltration rate, crusting, erodibility, and susceptibility to compaction. Changes in microbial populations or activity can precede detectable changes in the soil's physical and chemical properties, thereby providing an early sign of soil improvement or an early warning of soil degradation.