Bacteria

Bacteria are the most abundant microbes in the soil. There can be billions of bacteria in a single gram of soil. Populations of bacteria can boom or bust in the space of a few days in response to changes in soil moisture, soil temperature or substrate. Some bacteria species are very fragile and may be killed by slight changes in the soil environment. Others are extremely tough, and able to withstand severe conditions. Some bacteria are dependent on specific plant species.

There are several different types of bacteria:

Decomposers, which play a role in the early stages of decomposition.

Nitrogen fixers, which extract nitrogen gas from the air and convert it into forms that plants can use.

Disease suppressors, which release antibiotic substances to suppress particular competitors.

Actinobacteria, which help to slowly break down humates and humic acids in soils.

Aerobes, which need oxygen and dominate in well drained soils.

Anaerobes, which live without air and contribute to disease and rot.