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Compost Tea...Is It All The Same?
By Tad Hussey
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!