Compost Tea and the Underground Life of the Soil

Many of us have heard of compost, but what about compost tea? To understand compost tea we must first learn about the underground life of the soil. The life of the soil in large part remains hidden to us because, hey, it’s underground! What makes it even more hidden from us is that so much of the groundis hidden under concrete and asphalt. But the health of that life underground has direct repercussions on everything that grows. Covering the ground with concrete and asphalt, driving repeatedly over it with cars and heavy equipment, and dousing it with synthetic fertilizers and chemicals leaves the ground pretty void of life. But when left alone, like say, the ground of a healthy prairie or the forest floor, the ground remains full of life and activity. It’s easy for us not to pay attention to that level of life, but understanding how the life underground functions can teach us a lot about how to heal our planet.

All life on the planet functions in much the same way. Compare your body to the underground life of the soil. Your body needs three things to survive: water, air, and nutrients. Soil needs three things to support life: water, air, and nutrients. In the body, nutrients come from food, or organic matter. Food is broken down by our teeth, stomach enzymes and bacteria until they are in a form that can be carried to the necessary parts of our bodies in the blood. In the soil, nutrients come from organic matter that falls on the earth’s surface, like leaves, grass clippings, and dead things. The organic matter is broken down by worms, insects, and microorganisms which play a primary role in decomposition. This action of microorganisms, insects, and worms combing through the soil looking for organic matter to digest and break down, serves the second purpose of aerating the soil. Well aerated soil retains more moisture. The more moisture, air, and organic matter there is in the soil, the more life that soil can support. Chemicals kill the underground life of the soil. Compaction caused by heavy equipment, cars, and concrete squeezes the air, water, and life out of the soil. Using compost tea on your soil is the fastest way to breathe life back into the soil. Applying compost tea to your soil builds soil structure, decreases compaction, increases water retention, and helps prevent disease. It’s like giving your soil CPR.

So what is this magical stuff? True compost tea is a water extract of compost that is cold brewed to increase the number and activity of a diverse group of beneficial bacteria, fungi, protozoa and nematodes (microorganisms). Just like the soil and just like our bodies, the microorganisms in the brew need water, air, and nutrients to live. The microorganisms are extracted from healthy compost and rapidly multiply with the addition of air (with the help of some bubblers) and added nutrients like molasses, fish, and yucca extracts to the tea. Just like humans, microorganisms need one more key element to live, and that’s love. And who has time for love when you’re preoccupied by where you’re going to find your next meal, let alone your next breath of air! So the idea behind compost tea is creating a sort of heaven for those microorganisms with exceptional amounts of food and air. And under such conditions, the time is right for love! So microorganisms reproduce, and as their populations increase, the diversity of microorganisms increases. This diversity is good, because once the honeymoon is over and they’re released into the soil, it will enable them to adapt to a wide variety of soil conditions.

After about one to three days of constant aeration along with well-balanced meals, the microorganisms are energized and ready to be released into the soil and go to work for you. The tea is applied immediately because the longer the microorganisms sit around without aeration or added nutrients, the more competitive they become for the air and nutrients that are available. This competition can lead to decreased populations.

Once in the soil, all of these microorganisms are busy looking for food and oxygen. There are millions of different microorganisms in the soil that are adapted to the different foods exuded from the different plants as well as other microorganisms. Bacteria and fungi are the two major categories of microorganisms in the soil world.

Bacteria have many functions but their main function is to prevent disease. They do this by consuming all the food, and occupying all of the space that disease-causing microorganisms would otherwise take over. Consuming the food makes them walking masses of nutrients to be extracted for consumption by plants. Bacteria are responsible for transforming the nutrients in the soil into forms that plants can easily consume. Without bacteria, nutrients in the soil would remain inaccessible to plants. Also, in the processes of consuming and extracting food, the bacteria are creating the smallest of passageways for air and carbon dioxide to pass through the soil. This is an essential step in building good soil structure.

Fungi have a lot of the same functions in the soil as bacteria like preventing disease by consuming food and taking up space that would otherwise be taken over by the “bad” microorganisms, as well as building soil structure. These similar niches that bacteria and fungi occupy make for a competition in the soil between fungi and bacteria for resources (food) and space. The winner of this competition is determined by the kind of nutrients (food) available in the soil. Generally speaking, bacteria prefer the company of non-woody or herbaceous plants and fungi feast on the food exuded by the roots of woody plants. Compost tea recipes can be modified to produce a more fungi-dominated or bacteria-dominated tea.

Fungi in the soil function by attaching to the roots of woody plants, forming a very special, monogamous relationship with their host plant. Their only source of food is the stuff that’s exuded from the roots of their host plants. So to protect their source of food, they take it upon themselves to make sure their host plant gets all the nutrients it needs and is protected from taking in harmful elements. If the plant’s roots don’t have easy access to the nutrients they need, the fungi will actually go out and seek them from nutrient-producing bacteria. This relationship works out very well for both the fungus and the plant.

These relationships teach us that when left to its own devices, nature is very capable of taking care of itself. In healthy forests and prairies everyday bacteria and fungi are allowed to live and do their jobs of supplying air, water, and nutrients, as well as protecting plant life from disease, in peace. In soil that has literally had the air, water and nutrients squished out of it, and been poisoned by a steady diet of synthetic fertilizers and chemicals, compost tea is the antidote that can restore the life of the soil. So brew yourself some compost tea and let the healing begin!

For detailed instructions on how to brew compost tea go to:

Katie Schmitz
EAGLE (Environmental Association for Great Lakes Education)
Safe Lawn and Garden Campaign
Organic Gardening Specialist

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