Types of Soil Microbes

Soil microbes are microscopic particles that aide in the decomposition of organic materials. Microbes gain all of their energy from the sun, consuming the fixed carbon from organisms or from chemical reactions. Microbes are important in providing plants with the organic nutrition they need to grow.


The bacteria that are located in our soil are single-celled organisms that are approximately 1 micron in size. A bacterium is useful in the decomposition of organic matter, suppressing diseases in the soil and helping make useful particles small enough for plants to use. Bacteria microbes depend on the moisture in the soil in order to move. According to the United States Department of Agriculture, 1 teaspoon of productive soil contains between 100 million and 1 billion bacteria.

Algae and Fungi

Soil algae are microbes that survives in a layer of water in the soil. When they combine with the fungi in the soil they are called lichen. The algae photosynthesize and are used to feed the fungi, which breaks down and forms a rich fertilizer in the soil. They can usually be found on rotting trees, stumps, mossy logs and decaying soil. They help break the large particles down into usable nutrients.


Viruses in the soil can be devastating to a crop. They eat away at the plant and can destroy the health of garden beds. Insects such as aphids and beetles can spread viruses, along with bacteria and fungi. Viruses in the soil can contaminate our drinking water and can cause disease such as hepatitis in humans. They can infect the soil for a long time, which can destroy future crops.


Protozoa are single-celled organisms that are bigger than the bacteria in the soil. They like to live near the roots of plants and eat bacteria, other protozoa, fungi and organic materials in the soil. They consume nutrients that release nitrogen into the soil, which is a much-needed nutrient for plants. They also help to regulate the large numbers of bacteria in the soil. According to the United States Department of Agriculture, there are approximately a few thousand to over 1 million protozoa in 1 teaspoon of soil, depending on soil fertility.

Keywords: soil microbes, soil helpers, soil microbe types, composition of soil

About this Author

Melanie Hammontree is a member of the Society for Professional Journalists and has been writing since 2004. Works include publications with "Hall County Crime Examiner," "Player's Press" and "The Gainesville Times." Hammontree has a Master of Business and is working on a Master of Journalism from the University of Tennessee.