Is Compost Tea Just a Fad?

One of our readers recently pointed me in the direction of a rather interesting article on the Fine Gardening (magazine) website entitled, “The Jury is Still Out on Compost Tea“.

I have little doubt that the article has touched a nerve with many serious compost tea proponents, since it essentially questions the value of using teas for various gardening applications (strangely they don’t have a comments section after the article – would certainly be a great opportunity for an interesting discussion).

I must admit to feeling a wee bit defensive myself when I first read it, even though I’m not really a compost tea advocate (simply haven’t used it enough myself). While I certainly don’t doubt that the “jury is still out” as far as more research being needed etc, and while I have little doubt that there are some people making exaggerated or even completely false claims – I just can’t help but feel that the author is potentially tossing out the baby with the bath water.

Here is an interesting blurb from the article:

Before you start using compost tea by the gallon, be aware that most of the claims made concerning this liquid have been anecdotal and, even then, inconsistent. The positive results from scientific studies have been few and, again, lacking in results meaningful to backyard gardeners. A documented benefit created under sterile conditions, for example, does not translate to a benefit in your backyard, with its slew of natural microorganisms.

Again, I certainly agree that there are lots of wild (and often unsubstantiated) claims out there re: the value of various types of compost teas (including vermicompost teas, of course), but the inner science-guy in me doesn’t mind keeping an open mind about some of the “anecdotal” positive feedback I’ve received from a lot of people. Take my good friend, Mike “Strawberry Guy” Wellik, for instance (certainly looking forward to seeing what you have to say about all this, Mike!) – he is a very science-minded, rational individual (with academic training in entomology, if I’m not mistaken), and has determined via testing in his strawberry business that vermicompost tea applications can be very beneficial! His results aren’t published in the academic literature, but you know what – I’m inclined to take his word for it!

BTW – be sure to check out Mike’s recent YouTube video: Brewing and Using Vermicompost Tea

Dr. Clive Edwards, who was originally rather skeptical of compost teas (as stated in a “Castings Call” interview with Peter Bogdanov – will track down the specifics on that one), has even changed his tune in recent years, based on the promising findings of various research projects conducted by his team at The Ohio State University Soil Ecology Lab. He went so far as to refer to vermicompost teas as “almost magic” in an email he sent me, referring specifically to the success he had growing a prolific crop of cherry tomatoes in his own garden (uh-oh! Anecdotal results alert!! haha). This is an incredibly-accomplished (hundreds of academic publications to his name), “old school” scientist we’re talking about here!

I guess my main point here is that, even if we ignore all the promising (if nothing else) academic research results, I just don’t think we can say that ALL non-scientifically-proven claims should be ignored. Based on all that I have read – academic or otherwise – my gut feeling is that there is DEFINITELY some value in using compost teas!

Obviously, as is the case with “castings”, “compost”, “vermicompost” – we need some sort of firm definition of what exactly “compost tea” is. Not all teas are created equal, that’s for sure! Just because a certain type of tea produces a given set of results in a scientific study does not necessarily mean that another type of tea (or even the exact same tea) will produce the same results in the “real world” – so I guess, on that level, the author and I can agree. I simply feel that there is enough evidence (academic and anecdotal) to warrant a more optimistic view!

But hey – to each his/her own, right?

Anyway – I would LOVE to see what people have to say about this! MY comments section is open for business!

**Want Even More Fun With Worms? Sign Up for the RWC E-mail List Today!**
Previous Post

The Magic of Vermicompost

Next Post

Plum Worm Inn


    • linda
    • January 13, 2011

    an organic is so much better than a chemical ‘health drink’, ask the plants… they might not ‘shoot up to the sky in 5 mins’ but over all are much more healthy, a healthy happy veggie is a ‘good thing’ πŸ˜‰ i don’t really care about the ‘findings’, i just know my garden grows well with compost teas and other ‘health boosting methods…..

    • Panhandle
    • January 13, 2011

    How can breeding and applying beneficial microorganisms to your garden or crops be a fad? Sure, some people will have more success than others, some will stick to it, some won’t.

    Discount all the wild claims, listen to those who had limited success. If you take the middle position between these 2 ends of the spectrum we are better off than we were before.

  1. If you collect enough “anecdotal evidence” that yields consistant results it would seem to me that the anecdotal evidence become empirical in nature. A simple experiment with a number of plants in identical containers and media, some fed with compost tea and a like number as a control group fed just water, should be enough evidence to convince any individual conducting the experiment whether or not compost tea is worth the effort (at least for that particular species of plant).

    • Mike Green
    • January 13, 2011

    This last growing season I preformed a test where I left one third of my tomatoes with out any fertilizer, one third with miracle grow vegi fertilizer, and one third vermi treatments of castings and tea. All received the same water and sun. The results were pretty much as I figured…the plants with out any help were very small and struggled most of the summer(till I gave in and started giving them a booster) The miracle grow plants were jungle like and the vermi plants were somewhere in between. None of the plants showed any increased resistance to a late blight breakout I had, and all the fruit tasted pretty much the same. All that being said I still keep the worms working , and will still add it to my gardens, as I found it does not hurt anything and seems to be better then nothing. Besides the kids have come to love them and they make a great point of conversation.

  2. Hello Bentley, thank you for sharing. This topic has been on the back of my head since the 10th annual vermiculture conference @NCSU and yesterday I removed from my website what we call in Guatemala “liquid fertilizer”. No one in Guatemala, involved in vermiculture, has scientific data about compost tea. I believe a critical issue we could use to judge compost tea is its life spam. If the microorganisms can only live for 1 day in a recipient, then there is no point on producing it for the market. I was shocked at the conference when I heard “Its better than water”…
    worm regards from Guatemala.

    • Jason Kalka
    • January 13, 2011

    Linda Chalker-Scott and Elaine R Ingham are two huge names in the discussion of compost teas. They have very different views on the subject and both raise some great points. If you are just getting into brewing compost teas I suggest you read what both of them have to say.

  3. Im still going to give it a try.

    • Paulo Silva
    • January 13, 2011
    • Larry D.
    • January 13, 2011

    I just know,i have never been a green thumb.But when i started using vermicompost tea,it made it greener.One knowledgable person told me that people make the mistake of spraying the tops of their leaves,when you should be spraying the underside.
    Maybe the results are in my mind.But i will keep using it until it quits making me think it works.I’ve seen results first hand.No way i’m ever stopping making it!
    When you are multiplying microbes,fungae,etc.,how can this not be beneficial to plants?

    • Michael
    • January 13, 2011

    My thoughts are that if the compost tea is put in a healthy microbial soil then the plant will temporarily be helped. The microbes from the tea that die will release there nutrients into the soil. Then the microbes that are already in the soil will lockup most of the nutrients til the plant needs them. I believe in poorer soils, lacking microbial structure the impact of tea will be greater.

  4. Bentley is absolutely right and so are all of you. I haven’t even read what “Fine Gardening” said in total and my blood starts boiling. I have said a lot already about brewing vermicompost tea and believe it is a part of future commercial production of what we eat. The world cannot sustain the path we’re on and soon we won’t be able to afford to be on that path. Food prices will continue to skyrocket due to the ever increasing prices of the inputs.

    One consolation might be that “Fine Gardening” may not have the reach that it once did. I have personal experience with this. About 20 years ago I placed a classified ad with them to sell my plants. I received a LOT of responses, and they trickled in over a couple of years after the ad was run. Two years ago I ran a similar ad in their magazine and didn’t get a single response. My online advertising produces now what print advertising did 20 years ago. And, I might add, online advertising is much cheaper!!

    My conclusion is that the “mainstream media” so to speak in gardening and other disciplines is no longer print publications. It is the Internet. Case in point, the video I did about brewing vc tea has been viewed 529 times in short order, in large part due to Bentley posting it.

    One last point. I do agree that there is little practical data out there. Most is laboratory type of data which is where many studies begin. I think it is time to move it to the field and get hard data on the value of vc tea and compost tea. Unfortunately, to do it right it takes a lot of money. Replicated trials backed up with and correlated to laboratory analysis of the tea itself. Then, complicated statistical analysis and some sort of peer review to validate results.

    There is only one commercial operation that I know of that uses vc tea commercially on a mind boggling scale – in 1,000 gallon batches. Here’s a link:

    They are calling what they brew “Garden Espresso”. It’s vermicompost tea being injected into the irrigation system in a 4 acre greenhouse operation. Perhaps “Fine Gardening” should have done more research before making their statements? Truth be known, I think there are others out there doing something similar but keeping it under their hats for competitive reasons.

    In my business I get more questions than I care to deal with from the public who wants and somehow expects to get information for free, especially productivity (yield) data. I have to tell them that I am not the extension service with public funding. Conducting such studies have value to me in my business but when released gives my competition the information for free. It’s a dilemma I am still trying to find answers to.

  5. The jury (my family , friends and neighbors) already deliberated in my case and the vote was unanimous: Compost Tea is Guilty of growing huge healthy fruits and vegetables, detering bad bugs, attracting good bugs AND making all your fertilizer using neighbors switch over to the wonders of worm tea. Sentencing: must provide worm bin owner with unlimited supply of this liquid gold as she sees fit.

    Ahh, that was fun,

    • John
    • January 13, 2011

    I agree with both you and the author you quote. Both scientific inquiry and anecdotal experience are important. It is also important to remember that a scientist in one domain/field does not mean that same person approaches all things in life with the same scientific rigor.

    Anecdotal experience can provide a starting point for scientific inquiry. The strength (and limitation) of science is that it is very specific. A scientist would need to design hundreds of experiments to test all the different variations of compost tea out there. Also, scientists are usually interested in finding out why something works so that they can generate general principles. Casual gardeners, on the other hand, are more likely to just want to know does it work or not? That may not be easy to answer, especially when the answer is “sometimes” or “it depends”.

    The best solution is for scientists and enthusiasts to work together, each bringing their own strengths to answer important questions about this topic. The enthusiasts probably want to know the best procedures to use to get the best results. Scientists will also want that information so they can take it a bit further and learn why these procedures produce these results. Enthusiasts can help the scientists to know what may or may not be fruitful avenues of investigation based on their experiences.

    • John
    • January 13, 2011

    This reminds me of the arguments I see between proponents of herbal/alternative medicine and medical doctors. Going to either extreme is not good. I’ve seen “alternative medicine” cures including drinking one’s own urine and people that claim anything that is “natural” is healthy (very untrue…think toxic mushrooms). Similarly I’ve seen doctors completely discount anything related to alternative medicine claiming it to be untested and non scientific. (The funny thing is that much of Western medicine isn’t actually scientifically tested either.) I find these extremes of thought to be generally wrong-minded and non-productive for learning more about our world.

    In my opinion, the best results come from having an open, but scientific mind. Be observant. Approach one’s composting methodically, trying to make sure that all remains the same except the variables being tested. Keep notes. Share your results with the community.

    Personal experience and scientific research are different kinds of experiences and knowledge because they have different purposes. However, they do have areas of overlap and can work together to enhance our general understanding of phenomena. It is more productive to focus on what they share and how to facilitate that middle ground than for either side to point out the supposed weaknesses of the other.

    • Paul D. Fournier
    • January 14, 2011

    I’ve had some bad experiences with compost tea and will never be using it on my decorative indoor plants again. However, I’m inclined to believe the anecdotal evidence concerning vegetable & general outdoor gardening: the stuff seems to work like magic! I think that people run into problems when they think worm tea will be THE solution to their fertilization problems when the true answer is always multi-faceted and holistic. It’s not a silver bullet, but a (large?) piece of a gardener’s fertilizational arsenal. πŸ™‚

    • Mark from Roswell
    • January 14, 2011

    A few comments I could add:

    1. I have diverted 100’s of pounds of waste from the landfill (thanks worms)
    2. I use NO synthetic fertilizer
    3. Stuff grows like crazy
    4. If we believe soil is alive anything we do to help it is a good thing, right?
    5. Magic? Why not. Better than spending money on more synthetic chemicals

  6. I’ve tried the tea a few times using a control and didn’t have a real result however, I do know some credible vermicomposters that have. I just figured I was doing something wrong. I did notice that the VC tea never HARMED my plants.
    Heather, what do you think? πŸ™‚

    • Mart Hale
    • January 14, 2011

    This is the bacteria 5 hours into brewing ->

    This is the bacteria 24 hours after brewing

    I bought a microscope and camera to know what the results are. It is amazing the level of bacteria activity after brewing.

    I have been reading “Adding Biology” by Elaine R. Inghram For Soil and Hydroponic Systems. Still learning about this and learning but it makes sense to me that if you increase the diversity of bacteria population that the bad bugs will not have food to eat, or will have too much competition.

    • Steve Aitken
    • January 14, 2011

    Just to be clear about the Fine Gardening article (which I edited): The message isn’t that compost teas don’t work so you should use synthetics. It is that because many of the benefits of compost tea haven’t been verified by research, and you get all of those benefits by using compost (which you are making anyway), you might as well just use compost instead of going through all the effort to make compost tea.

    A better title might have been “Is Compost Tea better than Compost?” or “Is Compost Tea Worth the Effort?”

    The author of the article is Lee Reich, a soil scientist and organic gardener.

    • Bentley
    • January 14, 2011

    Wow – great discussion, everyone!

    Mike – thanks for chiming in and sharing your thoughts!
    John – Awesome contribution – very well put!
    Steve – I really appreciate you popping by! While I certainly didn’t think Lee was promoting inorganic fertilizers in any way, some may have interpreted the article that way – so thanks for clearing that up.
    I agree re: the article title, although I’ll still keep my optimism about compost tea being valuable for certain applications where compost use is not really a viable or convenient option! (also don’t think it needs to be an either/or argument in general)

    • Steve from St Louis
    • January 14, 2011

    I think Mr. Aitken may not have edited the whole article, or missed the last paragraph that states something about using tea in comparison to bringing coal to newcastle. If that isn’t a message that states “compost teas don’t work”, I’m not sure what else would. Also in that last paragraph the author states that the studies aren’t in. So the author wants you not to use something that has not been studied. We must all now throw out mom’s recepie book, it has not yet been studied, no matter how many times you have had good results.

    The author is a soil scientist, organic gardener, and someone that might want to consider writing a story about what is proven, and or about his own personal experience. Leave the supposition to the tabloids.

    • Steve Aitken
    • January 14, 2011

    “Bringining coal to Newcastle” doesn’t mean “compost teas don’t work.” One doesn’t bring coal to Newcastle because Newcastle already has plenty of coal and bringing more wouldn’t be worth the effort. The analogy is to emphasize that if one is using compost regularly, one doesn’t need to add compost tea: it just isn’t worth the effort.

    The author doesn’t want you to not use compost teas. He feels that using compost is more effective, a better use of your time, and has benefits supported by scientific study (which, to him, would be “proven”). I don’t think he is guilty of supposition in any way.

    If you would like to take this up with the author, I’m sure he can explain this better than I can. His website is

    • Steve from St Louis
    • January 14, 2011

    The title of the article was “Is Compost Tea Just a Fad? not “Go compost, it’s your birthday” I guess that I thought the title had something to do with the content in the article. I think that you were correct above when you said

    A better title might have been β€œIs Compost Tea better than Compost?” or β€œIs Compost Tea Worth the Effort?”

    All this aside, I want to thank you for becoming involved in the discussion and for making your viewpoint known. I appreciate your taking your time and investing it in the community of composters (worm or not). I also appreciate from hearing an oposing point of view. It helps to other perspectives.

    I did take it up with the author and he sent me links to other articles that were not very complimentary of compost tea. I love the sass.

    • Bentley
    • January 14, 2011

    Hi Steve (St Louis),
    MY article was “Is Compost Tea Just a Fad?” – but this was referring to Lee Reich’s question (in “The Jury is Still Out on Compost Tea” – the article I was writing about) of whether or not compost tea will “move beyond fad status”.

    Anyway – glad you were able to reach Mr. Reich! (thanks Steve A. for providing the additional info)

    • Frank
    • January 15, 2011

    Check out “The Compost Tea Brewing manual” 5th edition by

    Dr. Elaine Ingham for some non ancedotal scientific studies / results.

    There is an enormous range in what is called compost tea, and all along that spectrum one can find varying degrees of quality and helpfulness to plants. It is easy to make a compost tea; it is more difficult to consistantly make good compost tea that is teaming with beneficial microbial life. And, good compost tea can not be made without good compost; it has to start there. That is one reason I like VC so much. What comes out of the hind end of our little friends is consistantly rich in microbial life, and, therefore, can be the start of good compost tea. From the compost, the next step is brewing tea, and that is a completely different discussion. I will leave that for another time.

    I recommend reading “Teaming with Microbes” by Lowenfels & Lewis then tackle Dr. Ingham’s manual. Then, revisit your ideas about compost tea. Whether you are for it or against it, teach yourself what is actually going on in a compost pile or worm bin, and then take another look at compost tea, and why it works when it’s made right.

    It has been a facinating study for me, and eye opening, and I encourage everyone here to jump into the subject!

    +Frank in Simpsonville

  7. My personal experience shows that people have a major interest in compost tea.

    Somewhat embarrassing to admit: I have a picture on an online dating site that has me smiling with a batch of compost tea…I’ve received an insane amount of emails from girls asking how to make it, or saying they use it. I never thought my love of compost would attract the ladies!

    ANYWAY. My first few batches I would now call “leachate”, as they were anaerobic and smelled like sewer water. If you use this stuff on your plants, you could definitely kill them or at least piss them off. However, it’s easy to get it aerobic again and there you have it.

    So I would say there’s some room for error, but overall it’s pretty obvious to me that it works great.

  8. Way to go Tyler! Compost tea as a chick magnet! Who’da thought?

    If I was still single, I might not even care how much good it did to my plants! πŸ™‚

    • Larry D.
    • January 15, 2011

    A few things that should be noted.
    Some people confuse leachate for compost tea.

    Even as Mary Apelhof wrote.Some vc contains a higher concentration of salts from things like manure.Even scrap table food,that has been salted to taste.You pour a bunch of salty water on your plants,of course you will get bad results.It is not the vc teas fault,but the salts.Check for high concentrations.

    You must clean the tea maker every time.Study how to make it.You also add things like kelp extract and fish hydrosylate to boost what it does.Plain vc is not modified as tea is.You can make specific batches that will make your plants superior to others.Mike Wellik would not be wise to tell folks his secrets.People in competition with you will ruin your hard work and use it against you!

    When you put vc around your plants,and water it in.It is basically a watered down version of vc tea in my opinion any way!

    And lastly.VC tea is a way of expanding the vc.Down the road,this will be a necessity for tomorrows crops! It is already being used this way for a fact.No doubt it will not be declining in use.Farmers down the road will find they will make more of a profit by using this method.And they can spray this fairly easily!

    • Paula from Illinois
    • January 15, 2011

    I have see this in Utune people calling bin drippings compost tea. Even composting systems for sale advertise this as rich compost tea your plants will love.

    • Allison Jack
    • January 15, 2011

    Great discussion! I agree with the overall theme of the posts here that the best way to developing effective compost extracts is having scientists and practitioners work together so that the empirical “anecdotal” evidence and the experimental evidence can inform and build on each other. This is a point I’ve been making in grower talks for almost 8 years now :-).

    My work on non-aerated liquid vermicompost extracts is not out in the scientific literature yet (still writing!), but some of our main findings are in our publicly available grant report to the OFRF on our vermicompost outreach page.

    Table 2. shows a comparison of plant macro and micro nutrients between our non-aerated vermicompost extract and a common conventional liquid fertilizer. Our extract also consistently suppressed Pythium damping off in laboratory tests, even a week or two after sitting around in a bucket in the lab. This longer shelf life (which Maria mentioned as an issue with commercialization) is a major difference between aerated and non-aerated extracts in my experience and observations in the lab, although I have not directly compared the two. We also looked at freeze drying the extract and re-constituting it, which worked very well and the reconstituted extract retained its ability to suppress Pythium.

    I’ve chatted a lot with Mark Elzinga and his greenhouse manager Roger Rosenthal, the growers Michael mentions in his post. They use a combination of solid vermicompost and aerated liquid extracts of vermicompost for nutrient management in his commercial greenhouse.

    An important point I think the author of the Fine Gardening article left out, is that having a liquid source of plant nutrients is pretty important for commercial (and I would argue home) organic greenhouse production. Compost is great as a potting media amendment, however if you add the amount you would need to get all of the plant nutrients you need, you could end up with a drainage issue. I actually taught a lab on this in the Intro Soil Science course at Cornell. Compost has a very high water holding capacity, but in designing a potting mix you need to balance water holding with good drainage otherwise your plants’ roots literally drown for lack of oxygen. Most commercial organic greenhouse producers I’ve spoken with use compost or vermicompost in their potting mix, then have to use an OMRI listed liquid amendment like fish emulsion to supplement nutrients over the life of the plant. Remember, in a greenhouse system every time you water, nutrients actually leach out of the potting mix. Fish emulsion works great, and even has some documented disease suppression abilities, but it smells pretty bad.

    Even in the case of field soil crop production (i.e. not greenhouse), adding compost or vermicompost before planting is pretty easy, but the logistics of side-dressing with a solid material during the growing season can be more complicated. Having the ability to provide some of the plant-available nutrients and beneficial microbes found in compost or vermicompost directly through the irrigation system can be a benefit for some systems, but obviously so much more work is needed to scientifically document the benefits of what some growers are already doing.

    And taking my scientist hat off…I got great results this summer keeping my hanging baskets of fuschias blooming consistently all season with home made non-aerated vermicompost extract!

    It’s a really exciting time to be a scientist or a practitioner working with these materials. There is a lot of potential and so much left to be discovered! Can I also just say how much I enjoy the civility, curiosity and creativity of the redwormcomposting community of readers. I long ago stopped reading or posting on any compost tea groups because the level of discourse sank far below what I would characterize as civil!I’ll keep you all posted when my next papers come out.

  9. Allison! So great to have you pop by and share your thoughts!
    I definitely agree re: the level of civility here. I don’t know if I’ve just lucked out, but I’ve always been impressed with how polite and respectful people are when they leave comments here. I thought this MIGHT be the topic that would change all that!

    • Larry D.
    • January 15, 2011

    I should state as Allison did about fish emulsions.Fish hydrosylate goes through a slightly different process.But it probably smells even worse than emulsions.But boy does it work! It is basically fish ground up,and put into a bottle after the fish markets have used the good parts of the fish.It contains scales,bones and all.
    Also i found out about castings water retention.If you put solid vermicompost in a pot with a drip system,it tends to stop up,and quit draining.

  10. this is a freaking awesome discussion here… learning a lot. Thanks everyone!

  11. I agree with tyler. learning a lot form all the post.

  12. IMO- the ‘problem’ with worm tea is the same ‘problem’ with vermicompost. We expect the same results from all worm tea, when all worm tea is not the same. In fact, the vermicompost used to make the tea is different with each batch, so the tea has to be different. Because each worm system is fed differently, the results will vary, as they should.
    My problem with vermicompost and worm tea is the claims made by the sellers. Vermicompost is a poor fertilizer, at best, with very low N-P-K. But because of the micro-organisms, the nutrients are more readily available to the plants. This is my observation and not the result of lab experiments. If the major fertilizer producers sold vermicompost or worm tea, funding would be available to the labs to document the results. With worms available to everyone and tea easy to produce, I really don’t see the ‘big’ boys funding this research that would actually be competition to their business. Wurmz iz e-z!

    • John in Huntington Beach
    • January 17, 2011

    Great subject; great responses!! Thanks for being the catalyst, Bentley.

    A previous hyper-active post concerning drying of citrus peels included a comment with reference to “Teaming With Microbes,” Lowenfels & Lewis ( I obtained the book from my library and found it fascinating.

    The book draws heavily from the work of Dr Elaine Ingram, also mentioned in this thread, and other Soil-Web scientists. I thank the previous poster for alerting me to the book and recommend it to all of you.

    The book also emphasizes a point made by steamyb and others that all tea is not equal and that not every tea is suitable for every situation. Some teas are more bacterial and others more fungal. Each type has its place with bacterially dominant being more beneficial to veggies and fungally dominant to trees/shrubs.

    One of the book points that makes great sense to me is that what is most important as far as nutrients go is what happens at the root-soil interface, the rhizosphere. A healthy soil-web system, the book posits, delivers what the plant calls for at this critical interface versus the system of inorganic fertilization which delivers its dose to the entire soil structure, a small percentage of which affects the rhizosphere, the balance of which leaches into the subsoil and beyond, out of play. Thus the relatively low level NPK in compost and compost teas are more effective than the high level NPK rates of inorganic fertilizers.

    I hope I have not damaged anyone’s interest in the book by my weak interpretation of a small part of it. You owe it to yourselves to give it a read.

  13. Just a quick follow up on steamyb and John’s comments. Yes, there’s a high variability in compost and vermicompost extracts especially those made at home. However, the non-aerated vermicompost extract I helped develop with funding from the Organic Farming Research Foundation contained higher P & K than a synthetic 20-10-20 liquid fertilizer applied at a rate of 200 ppm. It also contained higher levels of micronutrients across the board when compared to a commonly used synthetic fertilizer. The only nutrient that was deficient was N, which could be supplied by other organic sources. These extracts are definitely a source of potentially beneficial microbes (and in our case consistently suppressed Pythium damping off), but don’t dismiss them so quickly as a good source of plant available nutrients!

    I’m really excited to see more research in this area. The availability of vermicomposts produced under highly controlled conditions with a consistent feedstock means that large scale use of vermicompost extracts for organic greenhouse nutrient management is already happening…and as scientists we are struggling to keep up with and document the new practices being developed by progressive growers.

    The neat thing about living in a democracy is that you, as taxpayers are funding a lot of research on organic agriculture through the USDA (thanks!) as well as non-profit research foundations like the OFRF. Organic agriculture isn’t as “fringe” in the research world as it used to be. Only 7% of university research is funded by industry (read that figure in Science magazine this morning at breakfast). This means the more citizens get involved in the political process, i.e. letting your senators know what kind of agricultural research you’d like to see prioritized in the 2012 Farm Bill, the more we can move in a more sustainable direction.

  14. I agree that all VC is not alike, for instance, I add alphafa pellets to my bin. I’m not sure about how much N I end up with but, 1 pound of it in my big bin sure heats up.

    • Frank
    • January 17, 2011

    Dear Alison,

    You wrote:

    “The availability of vermicomposts produced under highly controlled conditions with a consistent feedstock means that large scale use of vermicompost extracts for organic greenhouse nutrient management is already happening”

    For me and what I ultimately hope to do , consistancy and control is where the rubber meets the road. I want to come up with a way to consistantly create a compost product rich in benefcials which is repeatable and scalable. In order to have any hope of commercial success, it can’t be otherwise; the product has to be “the same” everytime. It sounds like you are in the thick of that part of the vermiculture world, and it is a pleasure and privilege to read your responses here on this site! Thank you.


    +Frank in Simpsonville

  15. I have to say that I find Allison’s report to be fascinating. One point that blew me away is that more is not always better. Her statements that higher numbers resulted in little or no suppression while lower number resulted in suppression is food for thought.

    The non aerated vermitea also surprises me to some extent. It is worth comparing to the way I brew the vermitea.

    I have been dealing with Pythium on strawberry seedlngs for a number of years. When I started using vermitea the problem all but went away. A number of other problems also became more manageable such as fungus gnats. I have also used vermitea on rare heirloom varieties that have NO disease resistance. Two years ago I used it on leaf scorch that was so bad that I thought I was going to lose my entire collection of a rare variety. After two applications of vermitea as a spray the plants started bouncing back and all survived.

    The section with the different modes of action against Pythium are also very interesting. I purchased Bacillus subtillis (brand Cease) and Pseudomonas corrugata (I believe this is Actinovate) last spring. Using the former for foliar application and the latter as a soil drench. Disease was not an issue at all after a couple of applications. I’m still using vermitea and the above products alternately during highly infectious periods in the spring. I also am forced to use sprinkler irrigation which brings on a lot of disease, especially in late spring and fall. Having these products is complementary to the vermicompost in the soil mix and twice monthly applications of vermitea.

  16. Oops! Actinovate is Streptomyces lydicus. Not sure of it’s mode of action. Not sure if there’s a commercial product for Pseudomonas corrugata?

  17. I tend to agree with the late, great George Carlin and acknowledge that I’m not in the ‘Club’. As a citizen in this democracy, I don’t control squat. Whoever, if I were a lobbyist for a huge conglomerate agro-biz with tons of money, I could ‘buy’ all the politicians to support anything I wanted to research and let the citizens pay for it. As it is, I really don’t want the government regulating my worms poop or the ‘tea’. πŸ™‚
    One more thing- how do we know that the microbes are good anyway. I read that bad microbes can happen, too. β€˜Biology of Earthworms’ Edwards,Lofty Chap.10 pg190-197
    One more thing- all I have ever read said aerobic = good and anaerobic = bad; when did that rule change? I need a nap! πŸ™‚
    And yea, Worm Tea is a fad- I just finished building a 55 gallon tea machine.

    • Heather
    • January 19, 2011

    Well, I’ve been away for a week and look what happens! great job Bentley and redworm discussers! For my customers, I make AAVCT, for most of my purposes, I have used non-aerated, which I brew overnight. My results are:
    1) like Allison and Mike–I did an experiment last spring with spinach and had a huge difference in germination and damping off in the tea group vs. the non tea group–HUGE!
    2) has stopped powdery mildew overnight, restoring cucumber vine to health while neighboring garden plots died
    3) Stopped brown patch fungus and allowed healthy grass to regrow into area. Neighbors who didn’t use it, still have the fungus
    4) Neighbors had black spot fungus on bush leaves, kept spraying chemicals, didn’t work. Finally asked for worm tea–gone after 1 application
    5) Much healthier plants than other neighboring garden plants. When other garden plots succumbed to blight, mine didn’t (until I went on 7 day vacation and it rained the whole time–came back and a few (but not all) tomato plants had it. Other gardeners’ tomato plants had been affected and died weeks before.

    So, do I think VC tea is the only tool–no, I certainly utilize alfalfa meal (mixed with VC) as a natural plant hormone source/nitrogen source, add rock minerals in the spring or when planting potatoes, and continuously add compost and mulch my plots with leaf mold…but that is about it.

    There is a wide degree of variation in quality of VC too. If you have newspaper and an occasional carrot thrown in your bin, because you are afraid of co-composters, smells or whatever (and there is worm composting training that promotes just that), there isn’t going to be as much value in the VC as when there is a variety of materials (well thought out) in your worm bin.

    The last thing I’ll add–one of the biggest frustrations when helping people garden, use amendments, etc., is the individual’s ability to follow directions. So, if they have a problem following directions when something is “ready to use”, I certainly would be concerned when “direction challenged” individuals would make quality VC, and brew tea themselves.

    Worm Tea on, I say!

    • Larry D.
    • January 20, 2011

    Bentley should have named this one”The truth about teas!” As Heather says,some people do not do well at directions.Most things i fly by the seat of my pants.VC tea is the exception. It is just like cooking though.No two people cook the same,follow the same protocol,etc.Things like having the tea maker spotless is important.Would you eat off of a dirty dish? You don’t just throw your tea equipment out in the yard and let the weather clean it for you.You need to follow strict standards.If someone was making synthetic fertilizer,they would not just pour in a bunch of junk.Why would someone do that with an organic solution? You will fail almost every time.Then tell everyone it doesn’t work,when it does!
    I truly feel on this one,that if you don’t believe it works,i would not waste my time making it.Just like if you don’t really feel like cooking.The food is seldom good! Me,myself? I am making ten gallons today.My grass will surely be greener than my neighbors again this year.And i can skip doses too.They can’t!

  18. What is the best way to clean/sanitize the bucket and air hose after each use. It will be my first time making it this spring?

    • Mart Hale
    • January 20, 2011


    Why such the fuss over cleaning out the 5 gallon bucket you are brewing compost tea in? After you have a clean bucket you are going to put compost dirt in it to brew the tea.

    I mean what is in the bucket that is not in the compost?


    • Bentley
    • January 20, 2011

    Wow – amazing discussion, everyone! (unfortunately haven’t had time to really dig through it all though).

    Larry – I myself would likely be careful using the word “truth”, since I don’t know the actual truth about compost teas any more than the author of the article in question (or anyone else here for that matter). We’re all just reaching our own conclusions based on the evidence in front of us. In MY world, the evidence looks good, though! haha

    I’ve always been really interested in the aerated vs non-aerated argument. Thanks very much for sharing your results, Allison (and others)! Interestingly enough, in “Vermiculture Technology” (recently discussed on the blog), Dr. Edwards writes:

    “In preliminary research on vermicompost teas in our laboratory (OSU Soil Ecology Lab), we made the important discovery that teas that were actively aerated during production had much greater effects on plant disease suppression than those that were not. Aerated teas also performed much more consistently than non-aerated teas. Hence, for all of our experiments we standardized our vermicompost tea production to use only aerated vermicompost teas.”

    (Quoted from: Chapter 14 – “Use of Aqueous Extracts From Vermicomposts”; p. 186)

    Certainly not trying to suggest anything here (re: value of aerated teas etc) – well, other than the fact that there is still LOTS of work to be done in this field, I guess! haha

  19. I’d like to briefly weigh in regarding the aerated vs. non-aerated vermicompost extracts. This is a perfect example of why it’s helpful to have many different people with different perspectives working with these materials. I actually just read Norm and Clive’s chapter this morning. The lowest vermicompost to water ratio they tested was 5%. In my experience working with these materials (7 years), we found that anything over about 3% vermicompost : water (by volume) in a non-aerated extract burned the root hairs off of germinating cucumber seeds. That’s why we finally settled on a 1:60 ratio for our experiments, which is about 1.6% vermicompost : water (by volume).

    The editors of the book invited me to include my results in my chapter, but I wasn’t willing to include anything that hasn’t yet appeared in a peer reviewed journal and been scientifically validated. But I’ll keep you all posted when the paper comes out! For now, these results are available to the public for grower outreach purposes in our OFRF grant report.

    The starting ratio of vermicompost to water is a major factor in determining the performance of non-aerated extracts. Right now it is impossible to draw comparisons between experiments conducted in different labs because not only is the vermicompost used in making the extracts different, but the vermicompost : water ratios are different too. We shared our results with Clive and Norm in 2008, but to my knowledge they have not tested the lower ratios that we found to be effective.

    • Larry D.
    • January 20, 2011

    Yeah,i forgot to mention always use IMO.In my opinion.Actually we have had people quit forums over discussing it.It is the hairiest subject that has ever had to do with worms it seems!
    Biofilm can affect the integrity of the tea from what i read.I’m certainly no scientist.But also if you don’t clean your tea maker,it is possible to breed e coli,salmonella,etc.Imagine breeding it every batch!
    From early research i had saw where the gov. said no one had ever died from it to their knowledge.But if i am going to be putting it on the greens my family is going to be eating(some raw)you can bet i am not taking chances needlessly.That is worse than eating with dirty hands when you think about multiplying pathogens.
    But just as Allison stated about an exact percentage for non aerated.Aerated is brewed to be fungal or bacterial.If you use dirty equipment you are probably never going to get the results you are looking for.You want to be as close to the same batch every time.Right down to if you do or don’t use molasses.Some folks are against using molasses too.So it is a preference type thing.This is why some peoples formulas are protected like treasure maps.No one can ever figure out your formula if you don’t tell them.
    Paula,i use hydrogen peroxide and whole grapefruit.I wash the bucket with the juice and peel.Then i soak the air stones in hydrogen peroxide.After that i rinse it again! I clean air hoses and all!
    I use kelp extract and some other stuff.But i quit using fish hydrosylate in the bucket.I put it in the soil instead.That stuff stinks to high heaven.You can wash the bucket 10 times and not get rid of the smell!

    • Don Smith
    • January 29, 2011

    The beauty of this discussion is that it points out many of the variables that come into play when trying to make a generic statement about compost tea.

    All compost, and vermicompost is not created equally – and good luck trying to find a “uniform” starting material, especially if that is coming from our current “green” waste stream. Even if you use composted cow manure to feed your worms – I can guarantee that the biology in each batch will be slightly different based on a myriad of factors. What time of year it was when the cows were feeding, what were they eating, what drugs if any were they given, etc. Different feedstocks yield different results. What temperature, moisture content, oxygen content was in the compost – did any or all of it ever go anaerobic? What was in the water you used to moisten the compost? Now feed this compost to your worms, and the worms and millions of other microbes and fungi will continue to break it down into what we call vermicompost – the nutrient levels will vary based on the original starting materials and all the variables along the entire process. Now, let’s take that vermicompost and make an actively aerated compost tea (AACT). What type of brewer are you using(different brewers produce different results using the “same” starting materials, are you monitoring dissolved oxygen content during the entire brew cycle? How long are you brewing? Are you using a microscope to analyze which microbes and how many are present? Are you adding anything else to your brew? Now, let’s apply this to the crop. Yep, you guessed it – how you apply it makes a difference – some spray nozzles will kill all the biology, or a lot of it before it reaches the leaves or roots of the plant – you actually need a microscope to see what your brew looks like after it comes out of the applicator/spray nozzle. Could you compare your results to someone in a different lab using a different microscope and lab procedures? And then of course – what time of day are you applying it – what was the weather, temperature, and humidity? All these things make a difference! And of course what crop are you applying it to? A Blenheim apricot is going to have different needs than a romanesco broccoli. Now how is that tea going to react to your particular soil?

    Okay, so there are a lot of variables – I’m a huge believer in the benefits of QUALITY compost, vermicompost, leachates, extracts, and teas – but trying to quantify the quality is the challenge. Dr. Ingham and Clive Edwards have done huge amounts of work in these areas, but the amount of things we don’t know about the interactions of chemistry and biology in the rhizosphere is staggering. We only know a small percentage of the actual microbes and fungi in the soil, and we don’t even know their actual function. Do we need to understand everything – NO! We have seen what happens when there is no biology in the soil, or only the kind that is detrimental to plant health. In broad generalities if we can get organic matter and biology back into the soil, soil structure improves, water retention improves, nutrient cycling comes back instead of leaching nutrients away, even compaction can be healed. And one of the best ways to do this is by using quality compost and vermicompost. Compost or vermicompost leachate or extract can help make the material go much further without the complexities of brewing – ultimately it helps get beneficial biology out in the soil. Anyone that is interested in learning more from Dr. Ingham should take one of her 5 Day seminars. If you want to go even further, take a Permaculture Design Course, and realize that is just the tip of the iceberg. If you care about this great big planet we call Earth, and all the life forms on it, try and do your little part to help make our way of life more regenerative, not just sustainable.


Leave a Reply

Your email address will not be published.

Get Your Free Vermicomposting Guide!

* Join the Red Worm Composting E-Mail List Today *