“The soil is not, as many suppose, a dead, inert substance. It is very much alive and dynamic. It teems with bacteria, actinomycetes, fungi, molds, yeasts, protozoa, algae and other minute organisms. This microbial population of the soil is concentrated mainly in the upper four or five inches where the bulk of the organic matter, their food, is to be found.” -J.I. Rodale, Pay Dirt, 1945