How microbes in the soil, support life above it.

Microbial biomass is the living mass of organisms in the soil. Having the soil in good physical and chemical condition and then feeding the microoganisms with organic residues is essential for keeping large and diverse populations of microbes alive. The microorganisms are responsive to added residues, and when conditions are favorable, biomass increases can reach their maximum within just a few days. Microbial biomass in soil can be quite extensive. Figure 3-23 show the mass of underground life to support life above ground. With a diversified diet (including meat), a typical North American needs approximately one acre of arable land for support. This figure illustrates the mass of a 200-pound person (mass above ground) versus the mass of organisms living below ground for that acre.