Soil is a complex system that supports plant growth and plays a very important role in the ecosystem. Soil is made up of different segments like organic matter, minerals, gases, liquids, and microorganisms. Each of these segments are unique based on geographical locations and can change depending on which natural or manmade forces influence the soil. Our main focus for this blog is the population of microorganisms that live within the soil, known as the soil food web and the role they play to support each other.
Understanding the Soil Food Web
The soil food web is made up of a community of microorganisms that spend some or all of their lives in the soil. They are extremely diverse in their size and function and can work in a symbiotic manner. Single-celled bacteria, algae, fungi, protozoa, nematodes, micro-arthropods, earthworms, insects, small vertebrates, and plants are all part of the soil food web.
The Soil Food Web. Image Courtesy: Richard Brackin - University of Queensland
A healthy soil food web helps in the retention of nutrients in the soil. It prevents nutrient leaching or loss in the soil. Good nutrient retention ultimately allows for a decrease in the need for fertilizers as they are already broken down into plant-available forms and at the rates that plants need. The soil food web also plays a key role in building the soil structure which is essential for oxygen, water and other nutrients to be absorbed into the soil. This allows plants to develop deep and well-structured root systems.
When the biology functions properly, water intake is optimal, the need for fertilizer is further reduced, and plant growth increases. The presence and growth of disease-causing organisms within a healthy soil food web is low because of the competition they face from the beneficial microorganisms. This in turn helps protects plants from diseases which can originate below the ground.
The Role of Microorganisms
In order for the soil food web to be in good health, an appropriate number of bacteria and fungi need to be present in the soil. This ratio maintains soil pH, soil structure, and guarantees that the nutrient cycling occurs at the rate and form needed by the plants.
Plants feed the bacteria and fungi by releasing 'exudates' through their roots into the area around the roots known as the rhizosphere. Exudates are secretions of sugars along with proteins and carbohydrates. The exudates that a plant secretes are specifically designed to attract desired species of fungi and bacteria that perform essential functions for the plant.
Every species of fungi and bacteria perform different functions. They produce unique enzymes that break down soil aggregates and mine different types of nutrients from organic material in the soil.
Image: Earthworms help to convert and make nutrients available for plants.
Plants need so much more than just nitrogen, phosphorus and potassium(NPK) for strong and abundant growth. They also need calcium, boron, magnesium, and up to 14 other micronutrients. The different microbial species present in the soil extract various nutrients as needed by the plant. They are activated only when needed by the plant and remain dormant until they are stimulated. When the plant encounters environmental stress (like drought or extreme precipitation) or has a nutrient deficiency, it can create specific exudates to attract microorganisms that will enable the plant to fix its deficiency or tolerate the environmental stress with significantly reduced damage.
Just like the fungi and bacteria have a specific function to mine nutrients in the soil, protozoa, nematodes, micro-arthropods, earthworms also have a special role to play. These creatures prey on and eat the fungi and bacteria – this is how the mined nutrients become available to plants. The concentration of the nutrients mined by the bacteria and fungi may not be suitable for theplant to directly absorb it. The predators help plants by processing and delivering the nutrients to the roots (in the rhizosphere) at levels easily absorbed by the them.
The soil food web is a complex living system made up of many different organisms that work in tandem to provide plants with the nutrients they need. As home gardeners, we can help our plants and the organisms present in the soil improve soil health by adding organic matter or a layer of mulch. Applying Nurture Growth Bio-fertilizer on your soil can also provide your soil with beneficial microbes that can stimulate a healthy soil food web!
If you have any questions about the soil food web or want to know more about how to improve soil health at home, feel free to write to us on firstname.lastname@example.org. Join us for our end-of-the-month webinar series for home gardeners to learn more about new trends and gardening tips!
Elizabeth hails from India, grew up in Dubai and travelled to more than 20 countries before settling down in Canada in 2018. The majority of her working life was spent in Advertising, assisting clients with executing successful brand launches and ad campaigns across industries such as CPG, fashion and real estate. At present, she is working on building up her skills in Digital Marketing and learning about new markets and processes. She loves animals and enjoys spending time with her cat Twinkie.