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When we think of the world around us, it’s easy only to imagine the big, physical things such as cars, buildings, and so on. However, we tend to overlook the tiny things we don’t get to see with our own eyes. An excellent example of these little things in our world is Soil Microbes.

Soil microbes are eminent in the soil and work well to foster the growth of plants. These microbes are sometimes referred to as microorganisms.

But what exactly are soil microbes and their roles in nature? You’ll find out the answers to this and more in this piece.

What are Soil Microbes?

In simple terms, soil microbes are defined as tiny microorganisms found in the soil. These tiny microorganisms are responsible for several microscopic functions within the earth. Soil microbes come in different shapes, types, and sizes. Based on this definition, soil microbes include bacteria, fungi, algae, and so on that are found within the soil.

Did you know that soil microbes have a long, significant history tied to that of the earth itself? Yes, these microorganisms have been around forever while gradually influencing ongoing activities within the soil. According to scientific findings, the first soil microbes were discovered about 2 – 4 billion years ago. They were found to have originated in the earth’s oceans.

These microorganisms quickly became popular because of their significance to plant life. Some of them were responsible for fixing nitrogen, while others released oxygen from inside the soil into the atmosphere. Gradually, these simple microbes evolved into more complex microorganisms that affect the fertility and structure of the earth.

While they are microscopic, soil microbes are also quite plentiful in any portion of the soil. For instance, you will find up to 10 million bacteria cells in every gram of soil located around plant roots. This region of the earth around the heart of plants is referred to as the rhizosphere.

The Common Types of Soil Microbes

Soil microbes vary in size, type, and function. This means that we have different soil microbes in any portion of the soil. The type of microbe located anywhere in the ground is dependent on the soil properties around that region. Meanwhile, here are the common types of soil microbes.


Bacteria act as the essential workforce in the soil. Asides from viruses, bacteria are the tiniest soil microbes. These soil organisms are responsible for the final stage of breaking down nutrients and releasing them into the soil. The Food and Agriculture Organisation described bacteria as one of the most valuable life forms in the soil. They are also the most abundant microbes in the ground.


Nematodes exist as microscopic worms that live around plant roots. There are numerous categories of nematodes. While some are harmful, others are beneficial. Furthermore, some nematodes will attack pathogens in the soil and convert them to nutrients for animals.


Similar to bacteria, fungi are found in the region around plant roots. There are different fungi based on the size, color, and shape of their reproductive spores. Their job is to synthesize nutrients and make them widely available and accessible to plants. For instance, Mycorrhizae is a popular fungus responsible for facilitating nutrient and water uptake into plant roots. These nutrients are then converted into amino acids, sugars, etc.


A long time ago, actinomycetes were classified as fungi because of their similar characteristics. However, parasitic actinomycetes will harm plant roots, while others in the soil will serve as living antibiotics and protect them from harm by other microorganisms.


Protozoa are larger than most microbes and are commonly found around bacteria. They are also renowned for predominantly eating bacteria. When bacteria consume nutrients, they are released back into the soil when larger protozoa eat up the bacteria.

The Role of Soil Microbes in Nature

You’ve learned the common type of soil microbes in nature, but what are the roles of different soil microbes in nature? Below are some of the roles of each soil microbes in nature;

Role of Bacteria

Bacteria are plentiful microscopic organisms beneficial for many important purposes, such as nitrogen fixation. Some forms of bacteria help break and weather soil particles. They do this by reacting with minerals within the soil. The composition of the earth is equivalent to the number of bacteria it contains. Therefore, soil with a high mineral composition will have more bacteria. You see, the accumulation of bacteria leads to aggregates that improve the earth’s health.

Role of Nematodes

Nematodes exist as segmented worms that are found in the soil in sparse quantities. These microorganisms function at varying trophic levels of the soil food web. Each nematode can handle a different set of functions in the earth.

These soil microbes help release mineral nutrients into the ground, also called nutrient cycling. The number of nematodes will influence the amount of prey in the soil. At higher soil densities, these microbes will reduce the amount of game found in the ground.

Role of Fungi

When you take a closer look at the soil, it’s clear that fungi are considerably lesser than Bacteria. However, they plan an equally important role in the sustenance of plant life. These microbes serve as a source of food for larger organisms and establish symbiotic relationships with plants and other organisms. The number of fungi in the soil is equivalent to organic matter. This is because most types of fungi rely on organic matter for sustenance.

Role of Actinomycetes

These are unique types of microbes. They exist as a type of bacteria that share similar properties with fungi. You see, these soil microorganisms are results of convergent evolution based on a shared habitat and lifestyle. One of the most renowned characteristics of actinomycetes is releasing antibiotics. Common examples of antibiotics include neomycin, tetracycline, streptomycin, and erythromycin.

Role of Protozoa

Protozoa are described as one of the first microorganisms capable of sexual reproduction. They are a significant step above copy by spore mechanism. These soil microbes are important because they mineralize nutrients within the soil. Their activities make mineral nutrients, such as phosphorus, nitrogen, and so on, readily available to plants and other soil microorganisms.

Where Do Soil Microbes Come From?

There are millions of individual species of microbes found in any portion of the soil. Even though they are invisible to the eye, these microorganisms influence the structure and fertility of the earth. But where do these microbes come from?

Soil Microbes exist as one of the main types of organic content found in soil particles. You can find them in any soil in different parts of the world. They are living organisms that occur naturally. However, they can be introduced manually by adding compost and natural fertilizers.

How Do You Identify Microbes In Soil?

Without any doubt, soil microbes play a significant role in determining soil properties, including the functioning of below-ground soil processes. However, we must know how to identify them to understand how they affect the earth and plants around them. Identifying soil microbes deals with the study of the following parameters;

  • Morphology – This is done by studying the shape and structure of soil microbes. For instance, bacteria often have a spherical, spiral, or rod shape.
  • Internal microbe composition
  • DNA structure
  • Molecular characteristics – the types of genes they contain and the type of molecules that are produced.

For some time now, unique biochemical and molecular techniques have been adopted to identify the microorganisms present in the soil. Furthermore, these techniques are used to classify and categorize different microbes in any given quantity of soil.

Essential techniques used in identifying and revealing details of microbial activities in the soil include; stable isotope probing, fluorescence in situ hybridization, microarray, terminal-restriction fragment length polymorphism, DNA fingerprinting, and random amplified polymorphic DNA.

Many of these modern and innovative techniques teach us about different general and individual characteristics of soil microbes.

How to Measure Microbes in the Soil

To measure the quantities of microbes in the soil can be pretty daunting if you don’t know how to do it. Well, to do this is not farfetched.

You start by measuring the amount of carbon, nitrogen, sulfur, and phosphorus in the soil. You can even use methods like:

  • ATP or Enzyme activity:This is done by measuring the amount of ATP or determining the type of enzyme in the soil. Generally, the higher the ATP, the greater the number of microbes in the soil.
  • Fumigation-extraction method:In this method, two soil samples are involved. The first soil sample is untreated, while the other is fumigated to alienate its microbes. During alienation, elements like nitrogen, sulfur, carbon, and phosphorus are released. So, the higher the amount of these elements released, the greater the number of microbes in the soil.

While it’s a great idea to measure the microbe content of soil particles, we have found it quite difficult to achieve effectively. This is due to the limited knowledge about most of these soil microbes.

How to Study Soil microbes under Microscope?

When using a microscope, you can study different properties of soil microbes in a larger dimension. You can use different microscopes to study soil microbes, but the most used one is the light microscope. The light microscopes resolution is around 0.2 μm or 200 nm. With this resolution, light microscopes are ineffective in viewing smaller microbes.

To use a microscope to study soil microbes, follow the procedure below:

  • First, get the soil sample that you wish to study.
  • Create an extraction solution and add it to the sample.
  • Next, drop the mixture on the slide and count the visible microorganisms.
  • Depending on what you are trying to identify, you may use special dyes to distinguish individual microbes from one another.

However, you may spot different types of soil microbes based on their physical characteristics. That is their structure, shape, size, and lots more.

Can you See Soil Microbes without a Microscope?

Since soil microbes are too tiny for the eye to see, then how can you see soil microbes without a microscope? Microbiologist has uncovered new techniques for identifying soil microbes even without a microscope. This modern technique includes:

  • Polymerase Chain Reaction (PCR)
  • Microarray
  • ELISA-based methods
  • Fatty acids profiling
  • Metabolic/chemo profiling

These techniques are carried out in different ways. Some of these techniques involve hybridization of microbes DNA, profiling microbe’s immunology, and using mass spectrometry.

What Happens If Soil Microbes Are Destroyed?

Like other living matter, soil microbes can be destroyed or killed under certain conditions. It’s crucial to note that soil microbes can be wasted due to excessive heat and changes in prevalent soil conditions at any particular period.

When these soil microbes get killed, they reduce fertility in the soil and accumulate mineral matter. Depending on the extent of damage of these microbes, the ground may lose its fertility completely.


It’s now clear that the soil ecosystem will fail to thrive without soil microbes. Soil microbes are essential not only to the soil but also to humans. Without soil microbes, plants may not produce the food we eat, and even the ecosystem will not be balanced.

Despite technological advancements and innovation, only little is known about the existence of soil microbes.

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