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As with everything, there is even controversy around how to make compost tea.
The two basic camps are anaerobic, or aerobic, and there is “scientific research” to back up both sides that you can easily find on google. The aerobic method “brews” beneficial bacteria with added oxygen, introduced by something like an aquarium pump, and this environment favors the bacteria that requires oxygen. Anaerobic is the opposite.
After reading way to much on this topic we invested in some supplies to start making the aerobic kind of compost tea. Two books have really started to reframe my mental approach to yardening, The One Straw Revolution, and Teaming with Microbes.
I’m now understanding why people are making such a fuss about till versus no-till, and the negative impact to your soil life even from something as simple as a basic chemical fertilizer. As a side, this guy gets into the Highly Uncivilized Hall of Fame for doing no till in an old refrigerator.
Aerobic compost tea increases the number of beneficial bacteria and other critters, which results in naturally healthy plants with good yield. Most importantly it creates or strengthens a soil web of life that controls disease and creates it’s own fertilizer for the plants. Some people swear by it, some people say it doesn’t work at all, and one person said it killed some of his plants. Test some on your plants first just in case. We are having positive results already and have not seen any plant mortality. The most positive results so far have been controlling a powdery mildew (or something that looks like it) and some big plant growth.
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This kit cost under $20, but you can probably do it for less. I couldn’t find an aquarium pump at my local pet store or garage sale so I bought a new one from Amazon because I had a credit there. I bought a two outlet air pump, 10′ of plastic tube and two air stones. I also got a five gallon plastic bucket from the garden area and a big rock to hold the air stone down. Here are the pics of the Tea Pot, and some white plant disease we are trying to kill.
You will also need:
- A couple of cups of compost – I use worm castings from my giant worm bin.
- Water with no chorine. Let your bucket of water sit out in the sun for a couple days and you should be fine. I use a 5 gallon bucket which needs 4 gallons of water.
- A source of sugar. Most sites recommend Molasses because of the additional nutrients available to the microbes. I’m using white table sugar, which works just dandy for other bacteria like Kombucha and seems to work fine for this. I use a tablespoon per gallon.
Take your bucket of water and turn on the air pump. Mix the compost and the sugar and add it to the water. I let mine run for about two days. It should have a sweet soil smell and it will produce foam and bubbles. When it’s done you can use it as a soil drench or a foliar spray. I do both. I also water it down a lot but I’ve also put it on the plants straight.
Every article and book I read has different ways to do this. Recipes can be for bacterial dominant tea or fungal dominant tea. Didn’t know this would be so danged complicated, eh? Here are some articles to give you a well rounded approach to investigating and experimenting.
Compost Junkie
Dirt Doctor
Captain Compost
Don’t run it too long or the bacteria run out of food and start to die. Don’t do it without oxygen or you grow bad bacteria. If you add other stuff like fish emulsion then something else happens but I don’t remember what.
I’m trying to keep it simple. Sugar and oxygen feed good bacteria that promote balanced healthy soil. The end.
Compost Tea by Brad Rowland is licensed under a Creative Commons Attribution 3.0 Unported License.
I imagine there is a huge “PEW” factor when it goes anaerobic, as there was with “worm tea” for me. I don’t know the “pros” to anaerobic, though.
Hi Roxanne. You’re totally right about the Pew Factor. I think the pros to anaerobic are around the leachate being a good fertilizer and also having ‘some’ beneficial micro-organisms but this is another place where there is way more controversy than I expected.
For instance with these two sites below, one says that leachate is potentially harmful if it goes totally anaerobic, and otherwise it’s a ‘waste’ of time, and the other site has comments that run the full range all the way to ‘plants love it.’ We used it in the past when I thought that’s what Compost Tea was, and our plants seemed to like it too.
the one caution that seems appropriate either way is to not let it go anaerobic if it contains manure, due to harmful pathogens, or if it does then just don’t use it on edibles.
For the time being we’re going to do aerobic only. After reading the book “Teaming with Microbes” the theory/science make the most sense to me.
http://forums.gardenweb.com/forums/load/verm/msg0622254920063.html
http://www.douggreensgarden.com/compost-tea-vs-manure-tea-vs-compost-leachate.html
I also favour the aerobic method, but you’ve really researched this well – I had no idea it was so involved. Glad to read you’re having such positive results!
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Hi Brad,
Thanks for the book recommendation of “Teaming With Microbes”. Now I’m even more inspired to make my own compost tea and encourage all those critters. Also, it made me appreciate the world of fungi (I’m also a mushroom forager) even more.
I loved that book. I already understood why I didn’t want to be ingesting chemicals, but it really opened my eyes about how chemicals destroy the soil-life-web.
What do you think about the compost used to make the tea. Our compost isn’t quite ready yet, but I have compost I picked up from the city. Do you think that’s good enough?
Hi Mil – I don’t know about the quality of the compost from the city. It should be something that is rich in microbes and should not have gotten too dry. I’m using the stuff from the worm bin. Can you get some from the local organic gardening place? Also at the beginning of the year we bought some compost ‘starter’ (hot compost starter) that is a rich bacterial mix to get your compost going. You may want to try that too. We had some piles of grass that got to dry so we used that to kick start it.
Mil,
I’d agree with Brad on this one. From my experience municipal compost is pretty low quality. What is nice about buying compost for compost tea purposes is that you don’t need a lot, so you can usually have it shipped to you. Also, as Brad suggested, you may want to start your own worm bin for your brewing needs. Vermicompost is a great for brewing bacterial-dominated teas.
Compost tea is probably a useful thing. But the matter is that it takes a lot of time to be prepared and nobody knows what kind of bacteria and funguses he brews. Instead of it you can take already done and guaranteed microorganisms which will work in the soil and on plants as fungicides and insecticides. Any harm, any lost time, any equipment. The whole you need is the biological preparation and water. To be sure visit the page http://www.zahyst-agro.com.ua Do not forget to push button English above to translate.
I’ve made and used aerobic compost tea with excellent results, but I’ve not made any in a couple years. I’m itching to get back into it now that I have extra time on my hands. One aspect I’ll be looking at is a means or replacing the sugar and molasses. I have to pay for those, and deep down, I’m a miser. I’ve been experimenting with using grass clippings (See: http://farmwhisperer.com/article/liquid-grass-clipping-fertilizer ) to produce a liquid fertilizer and the results have been wonderful. I’m thinking that along with the water soluble nutrients I should also be extracting some sugars. However, It makes sense to me that any extracted sugars would be consumed by microbes present in a 3 day steeping process, leaving nothing for the compost tea. Still, there are ample nutrients to give the compost tea a boost. I have a wheat grass juicer. I’ll try squeezing some grass and using that extract as a sugar/molasses replacement. Lots of things to try.