Soil Life:

Often Unnoticed but
Important Organisms

Why Soil Life Is Overlooked but Should Not Be

Did you know that soil is filled with life? But this fact is difficult to realize. Why? Because many soil organisms cannot be seen with the naked eye, since they are microscopic.

Although they may be small, these organisms play a major role in maintaining soil health. Why? Because they naturally promote the fertility and structure of soil.

How Soil Life Promotes Soil Fertility

Soil is fertile when it can provide plants with the nutrients that they need to grow and survive.

A major reason that these nutrients are present in soil is due to the activities of soil life.

Here are a few examples of how soil organisms contribute to soil fertility…

Nitrogen-fixing Bacteria

The bacteria that live in the roots of legumes (alfalfa, clover, lentils, etc.) fix nitrogen. These nitrogen-fixing bacteria transform atmospheric nitrogen into a nutrient, enabling plants to utilize it for growth, protein production and photosynthesis.


The bacteria and fungi that live in topsoil (the uppermost layer of soil) are decomposers.

Decomposers not only promote soil fertility but also purify the environment by:

  • Recycling Nutrients. During the decomposition process, bacteria and fungi recycle nutrients essential for the maintenance of life back into the environment.

    Here’s how this works:

    • Nutrients (food) become available for consumption after plants produce organic nutrients from inorganic nutrients during photosynthesis.
    • These organic nutrients can then be consumed by:

      • Autotrophs—producers that make their own food through photosynthesis such as green plants.
      • Heterotrophs—consumers that cannot produce their own food such as all animals including humans.
    • Ultimately, these organic nutrients produced by photosynthesizers fuel the vitality of nearly all living things, enabling them to grow and live.
    • Living things (humans, other animals and plants) are largely comprised of organic matter.
    • Living things excrete waste and die. Decayed organic matter (from animal waste, dead animals and plants) is called detritus.
    • Decomposers break down detritus into inorganic nutrients that plants can absorb as food.
    • Plants use these nutrients for photosynthesis and the cycle of organic nutrient production that provides life-supporting food for almost all living things begins again.
    This exchange of nutrients between living things enables life to go on. Without photosynthetic plants, we would not be able to consume the organic nutrients that enable us to grow and live.

    However, without the activities of decomposers, plants would not be fed the inorganic nutrients that they need to produce food for themselves and nearly all living organisms through photosynthesis.

    ...You may be wondering how plants provide the food that most living things depend on. Discover how on the soil fertility page.
  • Controlling Waste. When bacteria and fungi breakdown organic matter, they play a major role in waste control. Their work purifies the environment. Without decomposers, the environment would be enveloped with solid waste!

    Learn more about the significance of decomposers on the ecosystem definition page and on the importance of biodiversity page.

  • Developing Humus. I already mentioned that decomposers break down detritus (decayed organic matter) into inorganic plant nutrients. Bacteria and fungi release these inorganic nutrients into water, air and soil so that plants can absorb them.

    When decomposers break down detritus in the soil, it is converted into humus. You know that dark brown material you see in the uppermost layer of soil (topsoil)? That is humus.

    Humus aids soil fertility because it retains nutrients that plants need for survival.

    …but decomposers could not form humus without the help of detritus feeders…

Detritus Feeders

Decomposers break down detritus. However, they cannot decompose detritus until detritus feeders consume detritus first.

Here’s why:

  • Detritus feeders are larger than the microscopic decomposers (bacteria, fungi). They include: termites, slugs, earthworms and other soil organisms.
  • Once detritus feeders have digested detritus, it is broken down so that the smaller decomposer microorganisms can convert detritus into humus.

Therefore, due to their size, detritus feeders are able to contribute to the development of humus by assisting decomposers. This help is crucial, since humus is a natural, organic fertilizer that retains nutrients that plants need for growth and photosynthesis.

How Soil Life Promotes Soil Structure

Now you know that soil organisms promote soil fertility.

Additionally, soil life aids the structure of soil. A healthy soil structure in turn increases soil fertility and prevents soil erosion.

To explain how this connection works, I must return to my discussion about decomposers and detritus feeders…

How Soil Life Helps to Form Soil Structure

So, detritus feeders ingest detritus. Once these large soil organisms have digested detritus, decomposer microorganisms are able to convert it into humus.

Humus combines with soil particles, resulting in a porous soil surface. Openings also develop in soil thanks to detritus feeders such as earthworms that create tunnels when they move underground. Eventually, the structure of soil resembles a sponge.

A Spongy Soil Structure Prevents Soil Erosion and Increases Soil Fertility

So, soil develops a spongy structure with the help of decomposers, detritus feeders and other soil organisms.

This porous soil structure promotes soil health by:

  • Preventing Soil Erosion. Pores on the surface of soil enable it to soak up air and water. In a sense, these openings enable soil to absorb water like a sponge.

    Soil that can retain water (due to its pores) develops a stable structure, which helps soil to remain in place and to be less likely to erode. Learn more about soil erosion here.
  • Increasing Soil Fertility. So, pores on the surface of soil enable soil to retain water. And the capacity to hold water increases soil stability.

    A stable structure enables soil to prop up plants. When plants are propped up in porous soil they are able to absorb more water as well as carbon dioxide and sunlight—the inorganic nutrients and energy— that they need for photosynthesis.

    A spongy, stable structure also enables soil to retain additional nutrients so that plants can absorb them with their roots and use them for growth, protection against disease and other key functions.

    Learn more about these plant nutrients, photosynthesis and soil structure on the soil fertility page.

Soil Life Is Noticed by Organic Farmers

Organic farmers acknowledge the importance of soil life.

They note that soil inhabitants naturally increase soil fertility. They also know that these organisms help to maintain a stable soil structure that prevents erosion and also promotes soil fertility.

Therefore, organic farmers are sure to preserve soil organisms. How? By using agricultural practices such as soil conservation.

Click here to find my FREE e-book about soil conservation.

On the other hand, conventional farmers harm soil organisms when they utilize various farming techniques that degrade soil.

In fact, one of the major causes of soil degradation involves harming soil life...

...since without the help of these organisms, soil is more likely to become infertile and to erode...

...which leads to more environmental consequences.

Learn in detail about soil degradation here.

You can also find a brief summary of the differences between soil degradation and soil conservation on the soil erosion page.

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