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What Are the Functions of Soil Bacteria?

By Devin Dupre-Neary ; Updated September 21, 2017
A handful of soil contains more living organisms than the entire human population on Earth.

Soil bacteria perform number of functions that are a part of the symbiotic relationship they share with other life forms present in the soil. From useful bacteria like the Rhizobium, which keep the soil nitrogen rich, to numerous varieties of saprotrophic bacteria, which decompose organic matter and maintain the flow of matter and energy in an ecosystem, soil bacteria are a fundamental and integral part of the soil biome.

Maintaining the Energy Cycle

Soil bacteria form a major part of the group of organisms generally known as decomposers. These organisms, which also include some types of fungi, decompose all dead organic matter in the soil to basic nutrients, continuously rejuvenating and replenishing the land. Soil bacteria transform plant matter such as dead leaves and branches or fruits that fall off plants into vital nutrients like nitrogen and phosphorous, which in turn are absorbed by the plant roots, forming a continuous energy cycle. These activities of the bacteria aid healthy plant growth.

Cleaning the Soil

Bacteria in the soil break down manmade pollutants in the soil into harmless forms. Decomposing bacteria convert pollutants like pesticides, which otherwise adversely affect the chemical structure, into harmless constituents, thus keeping the soil clean. A clean soil not only promotes healthy growth of plants but also inhibits the absorption of pesticides into the fruits they produce.

Protecting Plants

Not all organisms living in the soil are beneficial for the plants growing in it. Many pathogens, including some types of bacteria, are detrimental to the growth and health of plants. Soil bacteria counteract such activities from other pathogens and bacteria, thus protecting the rooted plants from harm.

Fixing Nitrogen

A certain type of soil bacteria called Rhizobia prosper in the root nodules of leguminous plants. These lend the legumes their ability to fix atmospherically available nitrogen into the soil. Farmers and commercial cultivators use this activity in crop rotation techniques to replenish their land with nitrogenous nutrients by alternating staple crops with leguminous crops. This enables cultivators of crops to grow vigorous produce as well as maintain soil fertility.

Aerating Soil

Many phyto-bacteria also breathe out oxygen, as most plants do. Such species of soil bacteria aerate the soil, allowing the roots to breathe, and provide a lifeline to organisms like earthworms, which are also beneficial in maintaining soil structure and porosity.


About the Author


Based in Northern California, Devin Dupre-Neary has a bachelor's degree in nursing from UC Davis. Rather than move towards a master's or work in a hospital, he chose a different route. In 2009, he wrote professionally, part-time, writing articles on a host of subjects from health issues to gardening.