The Role of Microorganisms in Soil Health

When it comes to your soil, there’s a lot happening under the surface. Up to 10,000 things, to be specific! That’s how many species of soil microbes, a term applied to anything from beneficial bacteria to squatting fungi, can live in a single gram of soil.

But what exactly are these thousands of species getting up to? The answer is: a lot. We’ll cover what those microorganisms are, the many roles they play under the surface, how to cultivate more microorganisms in your garden, and the foolproof way to make sure your soil is rich with microorganisms in no time. We’re going deep.

What Are the Microorganisms That Live in Soil?

We couldn’t possibly explain what all 10,000 microorganisms are, but what we can do is sort them into five categories: bacteria, protozoa, actinomycetes, nematodes, and fungi. These microbe types each plays a different role in soil and plant health.


Bacteria may be undetectable to the human eye, but it is an absolute powerhouse for soil health. In fact, the Food and Agriculture Organization (FAO) once said thatbacteria may well be the most valuable of life forms in the soil.” Thats in part because it breaks down nutrients and releases them into a plants roots, and its the core microorganism type that does this job.


Protozoa are larger microbes that aid the process of moving nutrients from bacteria to plants. They are attracted to bacteria and rely on them as food sources. When they consume bacteria, the nutrients are then released into the soil. Without protozoa, bacteria microorganisms just wont be as efficient.


Not all microorganisms are just good, and actinomycetes are a bit of a wild card. They were once categorized as fungi because they establish a similar symbiotic relationship with the soil. But some actinomycetes are predators and could harm plants. Other actinomycetes can be beneficial to plants. As long as your soil is rich in microorganisms, the beneficial actinomycetes outweigh the predators.


Nematodes are similarly neither all predatory and neither all beneficial. They look like microscopic worms that live around or inside the plant. To enrich the soil, the good nematodes actually eat the pathogenic ones and secrete those nutrients directly to plant roots.


Fungi typically have a bad reputation, because its often seen as soil squatter that doesnt give back. But this is entirely untrue! Fungi work at the roots to make nutrients available to plants, and can even move nutrients between plants to promote their health.

What Is the Role of Microorganisms in Soil Health?

The role of microorganisms in soil health depends on the microorganisms themselves. Some decompose organic matter, while others fix nitrogen levels, while even others suppress pathogens to prevent disease. More roles include making phosphorus more readily available for consumption, suppressing pests, alleviating plant stress, and better-decomposing nutrients into the soil.

If it sounds like a lot, thats because it is. But lets take a cue from microorganisms, and break this further down.

Microorganisms-Rich Soil Means Healthier Humans

Are you growing food in that soil? As The Atlantic reports, the world of nutrition is just beginning to understand how microbiota in the soil is linked to the health of our diet. So what exactly do these microorganisms do for our health? As The Washington Post reports, Soil microbes help regulate our emotions and immune response. And they also play a key role in determining the nutrient content of our food.”

Microorganisms: Break It Down

You can think of these little creatures as organic, super-stable, and automatic fertilizer for your plants. Thats because microorganisms break down organic matter in the soil and release nutrients for plants to absorb.

Success for Soil Structure

By living and moving within the soil, microorganisms aggregate soil particles, creating pockets through which water and air can more easily move. This is essential for soil structure, which with the help of microorganism, betters over time. Soil with a strong structure is more resilient to erosion and drought because its able to retain more water and nutrients.

More Microorganisms Means Better Resilience

In addition to aiding structure, microorganisms maintain a balance of the soils ecosystem. Remember that some of these creatures eat each other, such as protozoa feeding on bacteria? Theres a whole food chain happening undetected under your soil, and it is essential for getting the right nutrients to your plants. Plus, supporting a diverse group of microorganisms in your soil means a healthier balance between creatures that are beneficial and predatory to your plants.

The First Step to Building Microorganisms: No Chemical Fertilizer!

Weve established that microorganisms are essential to the health of your soil. But one common practice is a sure killer of these important creatures: the use of chemical fertilizer.

As The Atlantic reports, Just as we have unwittingly destroyed vital microbes in the human gut through overuse of antibiotics and highly processed foods, we have recklessly devastated soil microbiota essential to plant health through overuse of certain chemical fertilizers, fungicides, herbicides, pesticides…”

Chemical fertilizers are often toxic to microorganisms because of their synthetic additives, as well as their increased potential for over fertilization.

Organic matter and organic farming practices, on the other hand, promote the growth of microorganisms and improve soil health. Because organic fertilizer doesnt have synthetic additives and adds nutrients to your soil gradually, its much more nourishing to your soils microorganisms.

Supporting Microorganisms Just Got Easier

Ready to consistently cultivate the diversity of microorganisms in your soil—and, by extension, the health of your plants? The easiest method to support these creatures is with automated lawn care, courtesy of the OtO device. By regulating soil moisture and implementing natural solutions in small and gradual applications, this genius device contributes a prolonged, positive effect on your soil. Over time, the OtO device will ensure your soil becomes less reliant on additional nutrient supplements and more resistant to disease.

Molasses in our fertilizer to feed microbes.

While you cant watch the diverse world of microorganisms working in your soil, seeing is still believing: just look for lush, vibrant, and healthy plants.

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