I realized that I had written this a while ago, but only published it on my newsletter, so I thought I’d post it on the blog for the world to read.
I’ve seen several inaccurate posts/articles about worm composting and in particular the uses for the liquid that often comes out of the bottom of a worm bin. This liquid is called leachate. The US Environmental Protection Agency provides us a handy definition of leachate: “Water that collects contaminants as it trickles through wastes, pesticides or fertilizers. Leaching may occur in farming areas, feedlots, and landfills, and may result in hazardous substances entering surface water, ground water, or soil.” The leachate out of the worm bin is not useful, and can be harmful. I know that some of the people I’ve interviewed have used it on their plants, judiciously. Forest says “I would just dump [it] down the toilet if it was bad. [some of the worm leachate] had sat for a couple weeks and that didn’t have the smell anymore. And that I would mix with water and then water my plants with it.”
But there’s a difference between leachate and compost tea. Compost tea is compost mixed with oxygenated water, creating “a Petri dish: favorable conditions are made for the beneficial soil microbes, already in abundance in worm castings, to reproduce millions of times over in the water culture.” Water running out of the bottom of your worm bin may or not be favorable to these beneficial aerobic microbes. Since it runs through the bottom, it may be collecting microbes that thrive in anaerobic conditions. These microbes, called “obligate anaerobes”, use chemicals other than oxygen to respirate. According to wikipedia, “[t]he most favorable [chemical for respiration] (after oxygen) is sulfate. [Byproducts of which] most of us are familiar with as the rotten egg smell”. This water probably also contains uncomposted organic matter, which is not what you want to apply to plants; otherwise we’d just dump our scraps directly on plants.
In short, what comes out of your worm bin is called leachate and is not compost tea. Don’t use it like compost tea. Dispose of it (I’d probably put it back in the worm bin, myself).
May 19th, 2010
Via the vermiculture_owner mailing list, I saw this PDF about vermicomposting tea production and its effects on plant growth. It’s from the November 2007 edition of BioCycle. It’s an interesting read; the takeaway for me was that “aerating vermicompost tea during brewing results in significant growth responses”.
February 7th, 2010
I just returned from the third annual Rocky Mountain Compost School, four days of classes about compost in Fort Collins. It was quite interesting, though definitely not aimed at home vermicomposters, home composters, or vermicomposters in general (I think the North Carolina Vermiculture conference would be a better be for vermis). The focus was on industrial composting, and all the intricacies therein.
I’m not complaining–there was a ton to learn and the conference was never billed as a home vermicomposting conference. Most of the attendees (there were about 20) were from Colorado and Wyoming municipalities that were composting or were thinking of composting. There was an attendee from the EPA, some environmental consulting companies, someone from Waste Not Recycling, two farmers, and me.
Among other things, I realized that instead of sending my worm castings to a soil lab to find out their chemical content, I should have sent it to a compost lab. One of the speakers, Will Brinton, runs Woods End, which does compost testing among other things. He mentioned that there were only seven labs capable of analyzing compost in the United States. (Europe has ~200, and compost running out of their ears, apparently.)
Large scale vermicomposting of biosolids, municipal waste, and yard waste doesn’t appear to be happening locally. If you are composting more than 100 cubic yards of waste yearly, the Colorado Department of Public Health and Environment regulates you, heavily . Wyoming doesn’t have any such regulations, and Illinois has some of them. Apparently, the EPA 503 rules, which deal with biosolids (humanure), are the starting point for many regulators, but each state then layers on their own regulations.
The class spent some time talking about compost tea. Again, this was specific to compost, and not to vermicompost, but I was amazed to learn that the main research focus of compost tea has been on increasing plant resistance to pathogens, *not* on increasing nutrient delivery to plants. Also, the common practice of adding sugars to compost tea during the brewing process actually increases the viability of E. coli (if any E. coli is present in the compost). And the bubblers that are often sold are overkill–simply stirring the compost tea three times a day with an oar is enough aeration.
Some of the other interesting talks including what it took to make compost that was certified as organic, experiences with composting dead animals, how applying compost to Colorado soil affected pH and organic matter, and the various standards and lack of standards in the compost market. There was also some hands on exercises and demonstrations: the class made and monitored a compost pile, measured the water content of compost, saw how to use the Solvita compost testing kit, and used a spreadsheet to build a compost recipe.
The class also toured two different municipal composting facilities (Cheyenne, WY and Boulder, CO). It was great to have a chance to ask questions of people on the ground, doing real industrial composting. Another interesting tidbit was the US Composting Council was started as a way to deal with the public relations problem of disposable diapers.
A highlight, for me, was visiting John Anderson’s worm farm but I’m hoping to get another post up with some pictures from that visit, so I won’t go over about that.
Compost making seems like a relatively young science. Brinton mentioned several times that there was a large amount of disagreement in many aspects of compost, including what it actually is, how the process works, and how to characterize it in terms of quality. There are few nationwide standards, and any group can put out their own standard (as a group of Colorado composters did a while back). The class was fascinating, and there’s a ton of work being done.
My overall takeaways from this course:
- finding a market for compost is the most difficult part of the process, but there are markets out there
- large scale composting is real and happening
- large scale vermicomposting is not prevalent, at least not around here
- compost nutrient value and process depends highly on the purity of ingredients
- there’s no ‘one way’ to make compost–how you make it depends on your end use
April 18th, 2009
I had the good fortune to interview Dan Matsch, who works at Eco-Cycle here in Boulder. They sell compost tea made from worm castings, and he and I had a great conversation ranging in topic from the benefits of compost tea to his experiences in home worm keeping to where Eco-Cycle gets feedstock for the worms. The entire interview is below.
Dan Moore: What is your position at Eco-Cycle?
Dan Matsch: Manager, Center for Hard-to-Recycle Materials (CHaRM) and Compost Dept.
Moore: How long have you been involved with vermiculture?
Matsch: ~20 years personally and professionally.
Moore: Do you care to elaborate on your 20 years of experience–that’s a long time!
Matsch: Prior to my career at Eco-Cycle I was an organic vegetable farmer for 13 years and always had a variety of vermicomposting projects going, mostly using the castings as part of a potting mix for my greenhouse transplants. And I’ve kept worms for my kitchen scraps at home for many years.
Moore: Are there any special challenges to vermicomposting in the Colorado area, as opposed to other parts of the country? Or is it all pretty much the same?
Matsch: Worms like 70 degrees F, high humidity within their living media and darkness. That doesn’t exactly describe Colorado’s climate, but the worms are native to a large part of North America including Colorado. They can fend for themselves in their native environment, but if you constrain them to a box and expect them to eat and reproduce at a certain level year-round, you have to monitor their habitat very closely. That’s why I always recommend to backyard composters that they use or build a bottomless worm bin that sits on top of – or better yet, is built into the ground. If the worms can escape adverse conditions by burrowing down, their survival and your success as a vermicomposter increases greatly.
Moore: Do you have any advice for small scale worm keepers?
Matsch: Keep them in the ground [as mentioned above].
Moore: Do you still keep worms at home?
Matsch: Yes, we have a 4’x8’ concrete block lined worm bed built into the ground in our back yard that produces about a cubic yard of castings every spring.
Moore: What has been your greatest success?
Matsch: Our Eco-Cycle high-tech compost tea worm farm is very fun, but I think the greatest reward is creating a closed-loop nutrient cycle at home because it’s so tangible. All our organic waste from kitchen scraps to yard waste go to the worms (the yard waste gets ground up first in a shredder). The worms and all the associated organisms break it down into castings, and that becomes the fertilizer for our gardens, which grow most of our food.
Moore: What kind of worms are used to create the compost tea?
Matsch: Eisenia Fetida.
Moore: How many worms?
Matsch: Our capacity is for about 150 lbs.
Moore: Is Eco-Cycle’s compost tea operation profitable?
Matsch: It’s within the realm of Eco-Cycle’s model of ‘cost + 10%’; however, we are doing it to raise awareness that food waste is a liability in the landfill, while a valuable soil amendment when composted or used to make high-value soil amendments like compost tea.
Moore: Where is [the tea] sold?
Matsch: Boulder Farmers’ Market on Saturdays, Eco-Cycle CHaRM on Wednesdays, April through September.
Moore: What kind of equipment is used to house the worms?
Matsch: We have a ‘flow-through worm digester’ that harvests castings from the bottom of their space, and we have a fiberglass worm farm that was originally manufactured by one of those ‘get rich quick growing worms’ scams that actually works quite well.
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Another View of the Eco-Cycle Worm Digester
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Eco-Cycle Worm Digester
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Eco-Cycle Worm Incubator
Moore: What kind of processing is needed to create the tea?
Matsch: Castings from the digester are ready to go with a turn of the harvest wheel; castings from the fiberglass farm must be hand-harvested, then screened, then formed into a cone in bright light to drive remaining worms to the bottom and slowly harvest castings from the sides. The brewing itself is much like brewing a pot of tea, except the water temperature is 70 degrees and the process is 24 hours. A better analogy of what is really happening, though, is a Petri dish: favorable conditions are made for the beneficial soil microbes, already in abundance in worm castings, to reproduce millions of times over in the water culture. So you are literally pouring microbes onto your soil when applying the tea.
Moore: How much tea is produced weekly?
Matsch: Currently we can brew 125 gallons twice a week, though we may expand by next season.
Moore: What are the benefits to the tea?
Matsch: The tea builds the population of beneficial soil microbes once applied. This improves a plant’s ability to uptake nutrients, since nutrients are exchanged by microbes at a plant’s root hairs. So with more microbes in the soil, more nutrients are exchanged with the root hairs.
Moore: Are you aware of any scientific studies testing the benefits?
Matsch: As with most organic soil amendments, funds for studies through land grant universities are very limited. The previous statement about the benefits is simple logic but has been confirmed at a basic level by Dr. Clive Edwards and his colleagues at Ohio State University. Beyond that, most studies I’ve read focus on whether tea can function effectively against various common plant diseases. Steve Scheuerell and Walter Mahaffee of Oregon State University conducted a literature review in 2002 called, “Compost Tea: Principles and Prospects for Plant Disease Control” which is widely quoted. They have since published several other reports.
As with compost, though, I think it’s difficult to understand what is happening with compost tea through the scientific method of reduction. Tea is not a fungicide. It works in several ways to outcompete leaf-borne disease organisms for food or space on the leaf surface, and it works to bolster a plant immune system. Like studies done on holistic medicine, applying scientific technique to the study of a specific disease creates many variables and therefore variable results. It’s like the old story about 10 different people getting drastically different results examining parts of an elephant in the dark.
Our own greenhouse trials have focused on how compost tea affects seedling plant growth. Control and test are always comparable until some kind of stress is introduced. Then it is quite clear that the test plants have a stronger immune system that powers through the stress with less – if any – check in growth.
Moore: What happens to the vermicompost after tea is made?
Matsch: It is still inoculated with soil microbes, so we let excess moisture evaporate for a week or so, aerate it, and mix it with worm food the next time we feed.
Moore: I’m curious about that, as it seems you’d just accumulate more and more vermicompost/castings, and eventually you’d need to clean out the digester and worm farm. Eventually, you end up with a mass of castings, don’t you? What happens to that?
Matsch: The baskets that hold the castings in the brewer are about 1/3 full after the tea is brewed, so a majority of the castings dissolve into the tea. Eventually we will produce a surplus of castings as the worm population maximizes, but both our worm farms get harvested pretty heavily during tea season and the boxes don’t have a lot in them by fall.
Moore: How much waste goes into the process?
Matsch: Theoretically the worms should be able to process half their weight daily. In reality, they are eating about 250 lbs per week.
Moore: What type of waste is it?
Matsch: Half food waste, half crushed dried leaves by volume. For the most part, it is organic vegetable kitchen scrap, but we give the worms a mixed diet. They have had a lot of apples this fall from a program in Boulder that picks up fallen apples from people’s yards to try to mitigate their attractiveness to bears.
Moore: How is waste collected, and from where?
Matsch: I either cherry pick from some of our Zero Waste Services restaurant or grocery store customers, or from material brought to our food waste drop-off at the CHaRM. We have some people bringing clean vegetative food waste specifically for the worms now…they may need their own collection dumpster soon!
Moore: What is the long term sustainability of people driving to drop food off for the ecocycle worm composters? Where does home vermicomposting fit into this picture (if at all)?
Matsch: Backyard composting is by far the most efficient way to handle organic waste – meaning kitchen and yard waste – and I strongly believe that worm composting is the best fit for the vast majority of people who want to backyard compost. Curbside collection of organics for commercial composting is the second-most efficient. The City of Boulder is slowly rolling that out for their residents, it’s an option for unincorporated county residents, and Eco-Cycle has collections for our commercial customers. But that doesn’t cover everybody, and not everybody can backyard compost. So a variety of solutions is necessary to keep organics out of the landfill.
December 21st, 2008
I had the pleasure of interviewing Forest, a classmate of mine. We talked widely about his experience with worms, including blue worms, his recent failure, the shelf life of compost tea, worms’ place in permaculture, and many other topics. It was a long interview, so I’ve broken it up into parts.
In part 1 he discusses his experiences vermicomposting restaurant scraps on a farm Hawaii.
Dan: I’m with Forest who was a classmate of mine and we’re going to talk about worms. Forest what’s your experience with worms and keeping worms.
Forest: My first experience with keeping worms? I went to Hawaii a couple years ago, I lived there for 6 months. And in the, in that term we were able to get a worm farm going on a small permaculture farm in Hawaii which ended up being the largest worm farm on Kauai. When I got there, they, the woman who was managing the farm there was operating had a small worm operation there and she wanted a larger one so I designed up a system to expand it and we had, I don’t know one the size of this room there.
D: That’s a good 30 feet
F: Yeah.
D: I would guess. How wide?
F: About 5 about 4 foot wide. What we did was we were collecting the compost from all the restaurants around us all the different restaurants. And then We would sell them our produce, if we had anything ripe we would bring it, see if they wanted to buy it or the compost, so that happened every single day. And so we collected enough compost from that to create a huge worm operation and it was awesome. It was really really cool.
D: So you did compost like vermicompost everything or just the vegetable scraps that they provided?
F: everything went into [the vermicomposting operation]. I mean it was huge you know, trash cans full of compost from all the restaurants and we threw everything in there every day. [We had] a long corridor so we started at one side and moved down and kept adding and move on so by the time we got partway down the line the first batches were ready to come off so that way, that way we could you know switch back, keep it up. We also had shade palms so it was completely shaded. But it also had a sprinkler system, a mister system on an automatic timer so that every so often it would just mist, keeping things misted all the time cause worms don’t like stuff to dry out. Plus when the sun was out even with the sun protection it would get a little hot there also.
D: And it was outside?
F: Yeah.
D: Did you have any issue with wild animals?
F: It was in our chicken bed, so we had to protect it from the chickens which was our biggest issue but that wasn’t that hard, because the way we designed it, it was closed off so the chickens couldn’t get at it.
D: Just chicken wire or something like that?
F: It was just a shade cloth. And we attached that to some long metal rods on either side and attached some PVC pipe and it [the PVC] half circled along it. So it looked a lot like a house.
D: And the chickens never figured it out? They weren’t smart enough to get through the shade cloth?
F: No [the cloth] was too thick.
D: Ok, gotcha.
F: They, occasionally, one would find its way in a little side pocket we forgot to close up but you know, a single chicken can’t hurt it so much. So we were extremely lucky. We tried other different types. We tried tires and boxes and a bunch of different ways but the amount of compost that we had, that’s what we’d use [the vermicomposting hoop houses]. I’m gonna change one thing I said. What we do is bring all the compost into the chicken pen and then let them pick through it for a day then we’d pick it up and we’d throw it into the worms. So the chickens got first pick. So we were able to feed our chickens [off the scraps].
D: You didn’t have to feed them anything else?
F: We did have to do a little bit of supplementing but I probably wouldn’t have if it was my chickens because I mean they eat all leftover pastries, bread, grain. If you [a restaurant] spilled some grain on the floor you just have to sweep it up and put it in the compost. They couldn’t cook with it so [the chickens] got stuff like that constantly. We had 60+ chickens there too so it was quite the large operation.
D: Were you involved in going to the restaurants and saying “hey, [can we get your scraps]?”. How’d you sell them on that?
F: We just said “we want your compost” and people were pretty excited about that actually.
D: They weren’t kind of pissed off that they would have to split their plastic waste from their food waste?
F: No.
D: Or did restaurants already do that?
F: No, restaurants didn’t do it but restaurants didn’t have a hard, tough time with it, I mean I think it’s partly the area we were living in was pretty liberal and pretty conscious and there wasn’t really any composting systems in place so you just start offering people the option and everybody jumped on it. The problem was just regular pickups because we had to do it every day, every two days we’d have to go and pick up every place and that doesn’t give you a lot of options for going backpacking for 3 days you know. So that was a management issue that ended up causing some problems but we had anywhere from 3 of us living on the farm to 20 of us living on the farm and it changed. It was just a huge invisible structure. Where we put most of our energy [was] trying to create an invisible structure. It’s managing people in flux, but the worms went well, you know, really well. And then after that I built a compost tea maker which is like a 55 gallon drum and then we’d take all the worm castings and separate the worms from the castings and then put that in the compost tea maker. And then we’d go spray down all of the plants with that.
D: Did you ever run any experiments on what compost tea was good for? I mean I mean how much it helped?
F: No, we just sprayed.
D: I mean I’ve wondered that because I’d like to. I mean Tracy was talking about selling that stuff, you know and it seems like that’s one way you could make a large body of stuff to sell.
F: Have you seen at the Saturday farmers market, Eco-cycle sells it there? So the problem with selling is it has to be in the ground within 12 hours of making it.
D: Oh really?
F: So that’s why they do the farmers market. Because they literally make it that morning and then they sell it.
D: Wow.
F: And so you’re buying it fresh and you have to go water your plants with it. There can’t be a delay.
D: Because all bacteria and all the good stuff will just…
F: It goes anaerobic. There’s a certain amount of oxygen in there and the microbes eat it. Once it’s done they kind of fall asleep
D: Sure.
F: So, you know you have to keep it while there’s oxygen in it. Now, if people could bring it home and put oxygen in it, you could use a little fish bubbler, it would last a little bit longer but even then not really [that long].
D: Ok that’s good to know; I didn’t know that
F: So we just spray everything with compost tea. I mean everything I’ve read and all the research I’ve done is it’s really incredible.
D: Really, ok.
F: So, yeah so I just want to explain the inputs to outputs of the worms. We had 3 acres we were taking care of so and then when I had this spring when we got worms…
D: Can I ask you a question about the farm? So how did you separate the worms?
F: Separate the worms? The woman who lived there, Crystal, she came up with a way to do it. You just take you take some old castings, flip them down into a wheelbarrow and then she took a tray that had like a screen on it that was big enough that the worms could crawl through, and we put the worms on the screen and then put that on top of the old castings and you just wheel it out into the hot sun, and the worms, once they reach a certain temperature, they’ll burrow down as quickly as they can to get away from the sun. You have to be careful if it’s a really hot day you have to put it in kind of half sun half shade you know. You don’t want to cook em but you want to frighten them that it is hot, then they’ll go down into the lower level. Then you just pull the top one out and it’s all cleaned out. It’s actually quite easy.
D: It sounds, again like a laborious process right, like you can’t do that with all your castings at once, you have to do repeated trips.
F: Yeah, exactly.
D: But like do that then you go work on the farm someplace else and then you come back?
F: And then this was invisible structures. There was the patterns of behavior. We’d wake up, go make our run [to the restaurants], feed our chickens, rake up yesterday’s [scraps and throw it in worm pits], then we go and take some castings, we put it in [the wheelbarrow separator], then let it sit all day, and then the next day, we’d take those castings and make compost tea with it and then be spraying. It’s just a lot.
D: Sure, lots and lots.
F: Plus 20 other things.
D: Sure yeah, this is a long[?] cycle you’re talking about.
To be continued…
(Thanks to Pam for her transcription skillz.)
December 2nd, 2008
