Both microbial biomass and microbial respiration are considered efficient indicators of soil health. Soil respiration is the measure of the carbon dioxide produced by the microbes in a given weight of soil while microbial biomass is the measure of the mass of microbes- both active and dormant. Microbial biomass (MB) is an excellent predictor of soil health because the size of the microbial population correlates with the available nutrients in the soil.