Soil Microbes / Microbial Biomass < 5% soil mass

• The microbial biomass of soil is defined as the part of the organic matter in the soil that constitutes living microorganisms smaller than the 5-10 um3

• The microbial biomass decompose plant and animal residues and soil organic matter to release carbon dioxide and plant available nutrients.

• The microbial biomass can be a measure of soil health and farming practise changes

Soil microbes can be divided into 4 groups:

Archae

A group of single celled micro-organisms that are similar to, but evolutionarily distinct from bacteria.

Bacteria

• Tiny one-celled organisms A teaspoon of soil generally contains between 100 million -> 1 billion.

• Typically, bacteria thrive on more simple carbon sources – “green materials”, molasses, sugar, fruit juice, milk, fish emulsion.

Fungi

• Microscopic plant-like cells that grow in long threadlike structures (hyphae) that make a mass called mycelium. 

• Four major groups of soil fungus: Zygomycota, Ascomycota, Basidiomycota, and Deuteromycota.

• Fungi require more complex carbons – cellulose, lignins, “brown materials” such as humates, woodchip, fish oils.

Protozoa

A group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic tissues and debris.