Garden & Greenhouse


Understanding the Importance of Beneficial Biology in Soil

Healthy soil contains thousands of organisms, both beneficial and detrimental. The trick is to find the balance between the two so the biology in the soil zone immediately surrounding a plant root system will stimulate healthy and productive plant growth. With the proper cultivation of beneficial biology in the soil, the following benefits are possible:

Benefits Provided by Beneficial Microorganisms

  • protection against pathogens
  • minimized nutrient leaching
  • increased fertilizer uptake
  • improved soil structure
  • decreased transplant shock
  • enhanced seed germination
  • promotes larger yields
  • increased roots and micro-roots
  • promotion of crop uniformity
  • aid in the production of natural plant growth hormones

Types of Beneficial Microorganisms

The types of microbiological organisms being utilized in the indoor gardening industry primarily belong to three groups: fungi, bacteria and protozoa and beneficial nematodes. Beneficial fungi have the ability to produce enzymes that break things like cellulose, humic substances, and chitin into smaller components, making them more digestible by bacteria and, ultimately, plants. Plant roots excrete sugars that are an additional food source for the fungus, which the fungus utilizes to produce its own humic acid-like compounds. These humic compounds are a food source for beneficial bacteria and protozoa. Beneficial bacteria and protozoa break down these humics and associated compounds, producing fulvic acid for the plant’s use.

Beneficial Fungi

As Gardeners we generally think of fungi as a problem, but not all fungi are created equal. Some intimately help plants; others rely on plants as a source of food. Just as penicillin is synthesized from mold, some types of beneficial fungus produce antibiotics that can be destroyers of plant pathogens. There are even some soil fungi that prey on insects and do not harm plants.

Like bacteria, fungi carry nutrients in their biomass. They are a major carrier of Calcium. Calcium in a soluble form is very important for plant root structure and plant cell structure. Fungi must be eaten to release a chelated and soluble form of Calcium. They are consumed by nematodes, chitin and cellulose degraders. Fungi are also a rich source of Carbon which is important for the long term health of growing environments. Fungi consume toxins and decompose carbon compounds such as humic acid. Mycorrhizal Fungi are vital for nutrient transfer with the plant. They exchange nutrients from organic matter and carbon sources within the plant root system in exchange for sugars. This exchange creates fungal chains and improved root structure, and prevents root occupation by pathogenic fungi.

Beneficial Bacteria

Just as there are good and bad fungi, there are both good and bad bacteria. Beneficial bacteria are the keepers of nutrients.

They consume and carry nutrients such as N, Ca, Fe, K, S and P in their biomass and release them for plant food when competitors such as fungi, protozoa or chitin and cellulose degraders consume them. Bacteria consume toxic materials present in the environment or released by anaerobic organisms. The glue which they use to attach themselves to root structures, leaf surfaces, soil, and soilless media creates aggregates, and passageways for air and water. This helps to maintain an aerobic environment keeping anaerobic or non-beneficial competitors out. Saprobic bacteria obtain food from decaying organic matter. They help produce nitrogen in a form plants can utilize, both from soil decay and atmospheric gas conversion.

Many aerobic soil bacteria also provide protection to growing plants. Bacillus subtilis is a beneficial bacterium
that provides protection from plant wilt fungi and helps retain moisture on plant surfaces. Protoctista and, like fungi, require an external source of food, with some exceptions. These creatures are typically utilized in biological, compost, and vermicompost teas for their ability to break down large soil-like particles into smaller bits and piece that bacterium and other fungi can process.

Oxygen is very important to hydroponics because anaerobic (without oxygen) systems, fosters the growth of fermentation or pathogenic bacteria. This is also true of the process of making compost, manure of other garden “tea”. That is why it is best to use a small air pump and air diffusion stone to help aerate the bucket when brewing these teas.

Protozoa and Beneficial Nematodes

Protozoa and beneficial nematodes are consumers of bacteria and fungi. Through their ingestion process, they release the nutrients contained in the biomass of the bacteria or fungi. This nutrient is released in a soluble form available to plants. Beneficial nematodes are an important part of disease control by consuming other non-beneficial nematodes that feed on plant roots.

The Importance of Pure Water

The importance of pure water is a gardening subject that is neglected, but it is critical to the promotion and maintenance of beneficial biology in the soil. Many gardeners amend their soil throughout the season with compost, earthworm castings, living bioextract solutions, and home brewed compost teas. This addition makes the soil and root zones even more active and teaming with life. What they often do not know is that by watering with straight, unfiltered hose water, they are killing thriving populations of micro-organisms or, at the least, severely affecting their numbers.

Some gardeners use de-chlorinating agents or other means to provide de-chlorinated water to their plants, but there are plenty of other problems, besides chlorine, that can also affect the living micro-biology. When extracting biology or applying microbial-rich solutions to your growing environment, reverse-osmosis-treated water is imperative. Reverse osmosis water will eliminate the harmful inhibitory elements such as chlorine, chloramines, and excess salts and your plants will definitely reflect the difference. For removing chlorine from hose water for watering plants, an inexpensive filter is recommended.

A wide variety of biological organisms are now available to the indoor and outdoor gardener. By harnessing the available microbiology all plants require, you will see the positive effects beneficial biology can have on your plants.

John Berends is a Garden & Greenhouse contributing editor.

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