Soil Bacteria's Role in Soil Conditioning

Bacteria are the unsung heroes of gardening. Without bacteria, gardeners would not have the rich, loamy soil in which plants grow without bounds. Bacteria are single-celled organisms that chemically digest organic matter in soils into smaller nutrient components in forms available to plants. There are hundreds of thousands of different kinds of bacteria, and many types of bacteria can digest hundreds of different forms of organic matter into humus. The bacteria are able to do this because they can produce many different types of enzymes to digest different compounds. Bacteria in Soil vs. Bacteria in Compost
Each type of bacteria works best under certain conditions. In a cool compost pile, or in garden soil, bacteria that thrive in cool conditions will form the bulk of the bacterial population. In hot compost, other bacteria that can survive the high temperatures dominate. When considering a bacterial soil conditioner, keep in mind the way in which you plan to use the conditioner. Understand the bacteria you are adding, if you are adding bacteria as soil conditioners, so that you add the right kind of bacteria. Once conditions change drastically, bacteria that cannot function in those conditions will perish. (Bacteria are not very mobile, unless they have water to float along in or wind to carry them.) The upside of bacterial immobility is that they will stay and multiply in place as long as conditions are favorable.

Bacteria for Soil Structure Improvement

Using a bacterial soil conditioning program not only helps with nutrient availability, it also helps to improve soil structure. Soils with poor structure benefit as bacteria breaks down soil compounds and the soil re-aggregates. Spaces for air and water will open up, and the structure of the soil will become more uniform.

Add Beneficial Bacteria for Oxygenation

Well structured soils provide plants with necessary oxygen in the root zone. Plants use carbon dioxide for photosynthesis, but they use oxygen for respiration, which is the process whereby plants break down stored sugars and starches to use as energy for growth. They get their oxygen by absorbing it in the root zone. Soils with good structure have plenty of spaces for oxygen. Soils without structure or organic matter generally do not have enough oxygen. When the plant cannot successfully undergo respiration, it cannot grow well.

Not all Bacteria is Good Bacteria

There are beneficial bacteria and there are bacteria that spread diseases. For bacteria to aid in soil conditioning, they need to be beneficial. Not just any bacteria will do. You can’t really open your refrigerator, grab something old and throw it in the garden! You need the type of bacteria that will function well in your soil, in your climate, to decompose organic matter. Good bacteria does something other than break down organic matter. Good bacteria in soil is instrumental in keeping harmful fungi and viruses at bay. Be careful about your source for garden bacteria. Many will sing the praises of compost tea for adding bacteria to your soil, but these teas can also add pathogens that will harm your plants. If adding bacteria to your soil, it is best to go with a reputable source that can provide beneficial bacteria that will produce results.


Casey Coke is a Marketing Manager for Natural Environmental Systems, LLC. The company is a global supplier of humic acid and other organic soil conditioners