compost tea brewer

Keep It Simple 5 Gallon Compost Tea Brewer

compost tea brewer

Keep It Simple 55 Gallon Compost Tea Brewer

compost tea brewer

Homemade Brewer

Actively Aerated Compost Tea

My first reaction to compost tea was a fairly common response, "So you just put compost in a bucket then dump it on your plants?"  Little did I realize all the science and work that goes into making high quality compost tea or AACT (Actively Aerated Compost Tea).  In some ways it seems like such a simple concept, to place good compost in  a container with water, add food for the bacteria and fungus in the compost, and then agitate and aerate the tea for a sufficient amount of time to allow the bacteria and fungus and micro-organisms to replicate and grow.  However, since this is a relatively new field, you seem to find many different ideas on what compost tea is, ranging from total ignorance to in-depth scientific study.  I've compiled a few points that I believe to be of significant importance when making compost tea:

  1. Good compost is very important!Without good biology in the compost, you really have no chance of getting high-quality tea.  You can only multiply what you put into your brewer, therefore good compost that has been tested to have high numbers and a diversity of beneficial organisms is essential.  A lot of science goes into making good compost, and unless you test your compost you really have no idea if what you are putting into your brewer is truly beneficial.  By adjusting the type of compost you put in the brewer you can control whether your tea is going to be bacterial or fungal dominated. We use a mix of 3 different composts to increase our diversity in our teas.
  2. Food is critical for the micro-organisms so that they can reproduce and grow in numbers.  The goal is to maximize your output of beneficial biology without giving the bacteria and fungi too much food that they over-replicate and cause the tea to go anaerobic.  There are many different recipes out there, each of which will give you different biology in the end and some are much better than others.  It is important to see the lab results of the recipe you use to make sure that you are indeed maximizing your final product.
  3. Oxygen! All living organisms need oxygen to survive, and your tea is no exception.  If you're not getting enough oxygen in your brew, then your tea will go anaerobic and you will start brewing the "bad" organisms (pathogens such as e.coli or root feeding nematodes) that may have existed in your original compost.  If your tea has enough oxygen and stays aerobic for the entire brew cycle, what you'll have at the end will be the good biology that you want for your plants.

These are the main ingredients I've discovered when making compost tea.  I'm constantly surprised by what people think of when they hear "compost tea."  I've heard it described as everything from "manure in a bucket," to "boutique fertilizer."  As the movement towards organics continues, I think we'll find more consensus on a definition of compost tea and also greater public knowledge on the subject. It is our job to educate others on the potential benefits of organics and compost tea!

Compost tea is an aerated solution that is teeming with billions of beneficial microorganisms that can be applied directly to the leaf surface of a plant as a foliar spray or used as a soil drench to improve root systems. Compost tea works by putting good biological diversity that your plant needs onto the leaf surface of the plant or the soil. You can enjoy the proven benefits of compost now in a liquid form. Many home gardeners and farmers use compost tea as an organic fertilizer to restore a much needed diversity and population of beneficial bacteria, fungi, and protozoa back into the soil foodweb. Others use compost tea as a foliar spray to reduce disease. Whatever your particular needs, compost tea will help you on the path towards a healthier, natural, organic garden!

The concept behind compost tea is quite simple, though the actual process of making compost tea becomes scientific and very complex. The idea is that compost (full of beneficial microorganisms) is put into water and then nutrients or foods for the microorganisms is added to allow the bacteria and fungi to multiply rapidly. Air is sent through the water to keep the water oxygenated, as this favors the beneficial bacteria and fungi over the pathogens (ex.-e coli). At the end of the brewing cycle, what you have is a concentrated liquid full of billions of microorganisms (bacteria, fungi, protozoa, nematodes) that can then be sprayed directly onto the leaf surface. This puts the "good" biology where the plant needs it to protect itself. It keeps the plant healthier and helps it to fight off potential diseases. The "good" biology occupies the infection sites on the leaf surface and is held there by simple sugars that the plant puts out (exidates) that work as a glue to keep the beneficial microorganisms thriving and protecting the plant. Compost tea has been used by many people all over the world with mixed results. Part of the problem relating to studies on compost tea is that there is a high diversity in the quality of the compost tea produced in many of these studies. After all, if you don't start with good compost, don't add the proper amount of nutrients, or don't keep the brew sufficiently aerated, you could be selecting for the "pathogens" rather than the "beneficials," and end up with compost tea that could potentially harm your plants. Much more likely is that the compost tea would be low in bacteria and fungi and have little more effect than putting water on your plant.

Aerated Compost Tea with good fungal content at 100x magnification

Aerated compost tea at 400 times magnification, what you see is a fungal strand with lots of active bacteria zooming around it.