Early civilizations in Greece, Rome and Israel recognized crops grew better when soil was supplemented with animal blood or manure. Soil fertility is naturally regenerated by the decay and decomposition of dead plants. Soil must provide the vast number of nutrients plants absorb through their roots. Plant physiologists therefore claim man must feed the soil not the plant. Soil is more than mud on my boots; soil is a dynamic living environment of bacteria, fungi, worms and beetles. A handful of dirt contains more bacteria than all the people on earth. Microorganisms feed on the starches in dead plant material falling on the ground in forests and fields. Microorganism metabolism converts dead plant protein into nitrogen-containing molecules that can be absorbed by plant roots so plants can produce new proteins, vitamins and other chemical molecules beneficial to the plant and man. At the same time, soil must contain some non-plant material like clay and sand so a plant can anchor its roots to stand erect.