<p>The microbial biomass of soil is defined as the part of the organic matter in the soil that constitutes living organisms smaller than the 5-10 mm^3.It is generally expressed in the milligrams of carbon per kilogram of soil or micrograms of carbons per gram of dry weight of soil. Typical biomass carbon ranges from 1 to 5% of soil organic matter. Biomass literally means “mass of living material” and can be expressed in units of weight (grams) or units of energy (calories or joules). Biomass is an important ecological parameter as it represents the quantity of energy being stored in a particular segment of biological community. </p> Measurement of biomass is used to determine standing crop of a population and transfer of energy between trophic levels within an ecosystem. A measure of the total microbial biomass in soil is often required when studying productivity or fertility of soils. Sometimes the biomass of specific parts of the microbiota is required-for example fungal biomass versus bacterial biomass.