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It’s Alive! | Benefits of Microbes in The Soil

The soil is not just a mass of eroded soil particles in which plants are anchored. If it was, nothing would grow on it. Good natural soil is a complex balance known as the soil food web, a vast interrelationship between plant roots, soil particles, the atmosphere, and the mass of living organisms present in the soil.


These microbes are so important that scientists have now come up with a name for organic soil which is rich in biodiversity - that is, many different types of these living organisms. They call it ‘functional soil’ due to the role it plays in plant and animal life.

What Are Soil Microbes

Microbes are living organisms that are too small to see with the naked eye. They are also called microorganisms, which is a more accurate term since ‘microbe’ typically refers to single-celled organisms.


Good garden soil contains large numbers of microbes, amounting to billions per cubic inch of rich soil. An article by University of Ohio soil specialists puts it thus, ‘There are more microbes in a teaspoonful of soil than there are people of earth.’


With such large numbers, it is apparent that these living organisms make up a significant part of the soil’s biomass, amounting to tons for every acre. Organic soil is, indeed, living in every sense of the word.


It is also not a stretch of imagination to say that such a large number of organisms must also play a big part in the soil’s characteristics. Ancient farmers had ideas about what a ‘good’ natural soil should be, and even took measures such as crop rotation and application of manure to improve its health.


These tiny organisms interact with plants in complex ways that even modern science is just beginning to decipher. While some are harmful, most are beneficial and even essential to a healthy balance of life in the soil.

Types of Microbes Found in Organic Soil

The microorganisms present in the soil are classified into different categories depending on what type they are and the role they play. Scientists recognize upto 7 types of these tiny organisms, but only six have functions in the soil ecosystem that are clearly understood.

  1. Bacteria

Bacteria account for the largest portion of living biomass in organic soil, with about 10 billion of them in every gram. An acre of wet soil has about 3 tonnes of bacteria, but their number and type varies greatly depending on different conditions.


Bacteria are found attached to the soil particles, particularly to the area around plant roots known as the rhizosphere. There, a complex symbiotic (mutual beneficiaries) relationship is thought to exist between plants and bacteria.


Plants can spend as much as 30% of their resources to make food for bacteria, which in turn help unlock nutrients and act as protection against diseases and pests.


They are also responsible for the breakdown of organic and some non-organic matter, which means that they cause decay. Bacteria are the most important life forms in garden soil as we know it, and are referred to as its crucial workforce.

  1. Soil Algae

Where there is a lot of moisture and nutrients, you can usually find soil algae growing. They are recognized and classified by color, such as blue-green, yellow-green, or green algae. They break down nutrients using sunlight for food.


You can usually find algae being grown in wastewater treatment plants because of their incredible properties of stabilizing dangerous chemicals and releasing oxygen into the air.

  1. Actinomycetes

Actinomycetes are a group of organisms that share similar characteristics with both fungi and bacteria. Scientifically, they are described as a type of Gram-positive bacteria and are commonly found in organic soil, air, water bodies, and plant remains such as compost.


When they grow really well, they produce thread-like filaments in the soil. They are the organisms responsible for the ‘earthy’ smell of freshly-turned garden soil and may just be the most important type of microbes after bacteria.


Actinomycetes favor neutral to slightly alkaline garden soils with a pH of not greater than 8.0. They are abundant in grasslands, and are also commonly known as ray-fungi. Some of their common species are Actinoplanes, Micromonospora, Microbispora, Nocardia, among others.

  1. Fungi

Fungi in natural soil are organisms that draw nutrients from organic matter, both dead and alive. They can occur either as single celled organisms or in large networks of masses called mycelium.


When they are not breaking down dead plants and animals for food, fungi can be found forming symbiotic relationships for mutual benefits - they make nutrients available to plants which then supply the fungi with plant food, usually sugars.


Fungi are known for producing antibiotics, and are actually the organisms that gave us penicillin. Despite that, there are many kinds of these organisms that can be harmful or beneficial to plant life.

  1. Protozoa

Protozoa are single-celled organisms which love to feed on bacteria, fungi, and soluble organic matter. As such, they are indispensable in garden soil because they help to keep the populations of other microorganisms in check.


When protozoa feed on bacteria, they in turn release the nutrients in the bacteria into the soil and help to keep the cycle of life going. They also release ammonium ions (NH4), which are important for fertilizing plant growth.

  1. Nematodes

Nematodes are simply tiny microscopic worms. They are tiny creatures which like to live inside plants, in water films around soil particles, and the upper layers of organic matter.


While nematodes in the soil are not fully understood, they get their nourishment from the cell cytoplasms of protozoa, bacteria, fungi, and other organisms. As such, they are in direct competition with these organisms, especially fungi.


Nematodes also release ammonium molecules from that found in the bacterium they consume, and their love-hate relationship with protozoa means that the two species cannot occur in large numbers in any particular soil.

Benefits of Soil Microbes

When you start to understand that microbes are part of an entire organic soil ecosystem, it becomes easier to understand how important their role is. They play a significant part in the functioning of this ecosystem, whose benefits extend far beyond the soil.

  1. Microbes decompose waste matter

These tiny organisms are responsible for breaking down organic matter into smaller components which plants can then take up for food. In fact, they help for a cycle where living plants take up nutrients from dead plants, then they die or are eaten, by the animals, and the process repeats.


They also help to break down the waste we put in the soil, including plastics. In so doing, microbes play an important role in protecting the ecosystem and resupplying ‘locked’ nutrients.


  1. Microbes improve the nutrient uptake of plants

Did you know that when you apply fertilizer to soil, only about 40-60% of it is taken up by plants? The rest is either locked up in unusable forms or lost in runoff water or in the form of volatile compounds.


However, microbes play a big role in improving the uptake of nutrients by plants. They do this naturally through processes such as fixation, solubilization, and phytohormone production.


This complementary effect of microbes on plant performance is so great that scientists are looking into how microbes can be supplied with fertilizer to improve uptake.

  1. They improve soil structure

When microbes break down organic matter, they release smaller particles that help bond the larger particles into aggregates. These aggregates are crucial for greater aeration in the soil, permeability to water, among other important characteristics.


Some of these microbes such as fungi and algae also produce strands or secrete compounds that bind the soil together. One of the most important results of this aggregation is that the resultant organic soil will then be able to retain more water.


  1. They help break down carbon

Microbes play a major role in the carbon cycle. They break down living things (organic matter) into more usable forms of carbon, which other plants can then take up.


Others break down carbon dioxide in the atmosphere to yield energy. An example of these are yeasts, which in the absence of oxygen can break down carbon dioxide and in fermentation.


  1. Microbes produce ammonia from nitrogen in the air

Nitrogen-fixing bacteria have been known by scientists and farmers alike. Legumes like peas have nodules in their roots with billions of these to help them ‘fix’ nitrogen in the air into more usable forms such as ammonia.


Apart from bacteria, some other microbes such as protozoa and nematodes also release ammonia when they feed on bacteria in the soil. Thus, it is more of a synergistic effect whose overall result helps improve natural soil fertility and plant growth.


  1. They degrade pesticides and detoxify the soil

Microbes don’t just break down physical matter. In their search for food, they also degrade otherwise toxic chemicals in the soil such as pesticides and excess fertilizers into more benign and useful plant compounds.


These organisms are able to do this through complex metabolic processes. Even though they may get harmed in the process, they help protect plants and other life in garden soil from further damage. Even oil spills and nuclear waste depend on such tiny organisms to clean up and detoxify the soil.


  1. Microbes control diseases and pests

While some microbes are themselves the cause of diseases in plants, many actually stimulate immunity to plant diseases. This is an important point, in a world where about 30% of food production is lost to diseases even before it reaches the consumer.


Instead of using a lot of chemicals to prevent plant diseases, microbes can be used in their place. Some diseases like the dreaded wilt can be completely avoided with the right microbiome, which also helps to keep away harmful pests.


  1. Direct action: they help improve human immunity

In a more direct effect, microbes in organic soil have been shown to have a complex and largely beneficial role in human health. Researchers from all around the world came together to investigate a phenomena in Germany where farm kids had much lower incidences of allergies and chronic conditions than those in the city.


The results proved that microbes in the soil have a way of stimulating and strengthening human immunity. Today, there are even organic soils and similar products being sold as immunity boosters, although that is definitely not the way to do it.

How to Improve Microbial Life in Garden Soil

Since microbial life is so important in the soil, we naturally should take steps to make sure that it is cultivated and protected. You can opt to buy already healthy organic soil for your gardening. Ancient Path Naturals are long time experts in soil and its fertility, who can bring you organic soil to transform your garden.


If you just want to improve what you already have, there are various methods supported by science to help improve soil microbe content and biodiversity.


  1. Use of organic fertilisers

Using organic fertilizers such as manure and compost is more sustainable than using artificial ones. They help promote microbial activity and introduce more organic matter.


  1. Monitor and control soil pH

Prolonged cultivation and application of fertilizer tends to lower soil pH and make it acidic. Microbes require an environment that is more neutral, so balancing pH can help improve the microbe living conditions.


  1. Crop rotation

Practiced since ancient times, crop rotation is more about controlling harmful microbes and preventing spread of plant diseases. It also helps improve plant nutrition, especially why you rotate monocultures (like wheat) with legumes.


  1. Minimal tilling to protect the topsoil

Most of the microbe population is in the topsoil and humus. Tilling turns over the soil and breaks up the networks of microbial life, besides exposing them to the hot sun. Instead, you can drill only the spot where planting is going to be done and retain plant stubble.


  1. Maintain plant cover

During off seasons, plant cover crops to maintain moisture, add organic matter, and protect the soil.


  1. Introduction of organic matter into the soil

Organic matter has a lot of biodiversity which it can help add into the soil. Adding mulch, plant-based compost, and other rich organic matter helps boost the microbe numbers in the natural soil.


  1. Introduce the microorganisms directly

If your soil is particularly degraded, you can add some microbes directly. Mycorrhiza filaments help add fungi, probiotics add bacteria, and even some worm castings.


Healthy natural soil is living soil. It not only ensures healthy plant growth, but also increases productivity and protects from harmful plant diseases.


If you’re looking for healthy, natural, and fertile garden soil, APN Garden Planting Mix is the best all-purpose and ready to use organic plant soil. With it, you can expect all these benefits and more, no matter what you want to grow in it.


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