When I bought my first worms, the vendor sent a fact sheet with the worms and stated unequivocally that the liquid that comes out of the bottom of your worm bin is not compost tea, but rather it is simply worm leachate and should never be used on your plants. They then continued with their recipe /instructions for worm castings tea. Their contention was that the leachate was in fact a byproduct of the rotting food in the bin and could contain harmful bacteria and/or fungi.
Since then I have read several arguments on both sides of this discussion. Recently I watched a Youtube video of Geoff Lawton's on making worm castings outside in a big old bathtub. I can't find the link right now as my internet connection is a bit slow. He would fill the bathtub with manure and then add the worms. He watered the bin well and then collected the overflow to put on his plants. When the castings were complete, he started feeding the worms at one end of the bathtub and after a few days he harvested the other end of the bin. Then he replaced the emptied area with more manure and the process started again.
I would definitely give more credence to Geoff Lawton then the worm purveyor that I purchased the worms from. In his video he collects the water that he runs through his bin to make sure it is sufficiently damp and uses the leachate/tea at full or half strength to feed his garden. I also read somewhere else that suggested you pour the leachate that ran through your worm bin back into the bin to keep the worms moist. You could add a bit more water if needed to make sure it is sufficiently damp. As an aside, you need to make certain that your bin has good drainage holes. You can use the overflow to feed your plants.
My take on the whole thing is that if you have a decent amount of worm castings in your bin then even if some of the liquid is from rotting vegetables that the benefits from the worm castings will way outweigh any potential negatives. Also if the overflow amount is fairly shallow in the bottom bin it should stay reasonably aerobic, especially if you cycle the leachate through the bin regularly. I thought about possibly collecting the excess from several bins and bubbling some air through the liquid for several hours before using it. This would give a big leg up to the aerobic (good) bacteria.
The counterpoint to collecting the leachate from the bin is to make worm tea. To do this take a handful of finished castings and put it in some cheese cloth. Put a couple gallons of water in a 5 gallon bucket and bubble air through the water. If the water is chlorinated, bubble it with air for 24 hours and then suspend the worm casting "tea bag" in the bucket and also add a couple teaspoons of molasses to feed the bacteria. If the water was not chlorinated you can skip the first 24 hour bubbling. Some people say a few hours is sufficient to leach the castings, but I prefer to do it for 24 hours with the castings. I think that if you are using the worm tea for foliar feeding, that worm tea such as this is the preferred method.
My belief is that the bin leachate is just great for feeding/watering the roots of the plants.
So what do you all you worm castings and worm tea experts think?
Well, here's my off the cuff thoughts, backed by nothing, basically just bro-science. But it seems like while some of it may be "rotting vegetable lechate" I don't see how that's a bad thing, it's going to be the same bacteria as what's coming out of the worms rear ends, right?
Also, if it's leaching through castings at the bottom of the bin, it is at least partially actual worm casting tea. I wouldn't worry about using it, myself, though I would probably use my bubbler, as you mentioned, in a bucket to favor the aerobic bacteria over the anaerobes, also to grow more of them, maybe add some molasses to feed them while doing so. But even if not at least the aeration will kill off a lot of the anaerobes and then there's no concern at all as far as I can see.
I now do worms in buckets without drainage holes, as I got tired of dealing with the leachate. I just add a significantly higher percentage of paper than food, and leave the lid mostly open. and have 2-3 buckets on rotation - usually one that's sitting, and 1-2 I am filling, and I chose which bucket to put stuff in based on how moist the bucket is. Seems to work well enough without the mess.
When I had a more traditional worm bin, I never considered NOT using the leachate from my worm bins to feed plants. I typically diluted it 3:1 or so. I definitely have seen a jump in growth when I apply the liquid to tomato plants.
My argument to your worm-seller would be - everything is coming from the same source, so why would the bacteria populations be signifiicantly different? My observations on my bin seem to be that the worms wait for some bacteria to break down and soften the food before they touch it, so there should be a significant population of bacteria in a bin that rot vegetables anyway. Perhaps you get more anaerobic bacteria in the liquid, but I don't know why that would be a big negative? Plus, if the bin is very wet, a lot of water-soluble minerals/vitamins should be in the liquid.
I like your idea about using a bubbler on compost tea/leachate. I usually let mine sit 24 hours and stir it a few times to aerate it, but a bubbler would probably work better.
Rotting vegetation leachate is a good fertilizer in and of itself. Some of this is because of the actual nutrients, but more important by far are the teaming hordes of microbes in the leachate.
I used to make compost piles in some obscure corner of my property, seemingly as everyone does. That was until I put one in an orchard. The pile was ever so slightly uphill from a peach tree. The leachate from the pile made a nice, dark green stripe that just barely included the peach tree. For at least 3 years the grass and tree grew faster, better and noticeably more healthy than outside the stripe. The tree grew twice as fast as its neighbors. All of this was because of leachate from a hastily made compost pile.
I now make compost piles IN the garden instead of wasting their potential in some corner I will never use. The ground below is magically fertile.
So what is the relevance to your situation? Leachate is great for soil fertility whether it came directly from a worm or decaying matter. For my part, I say use that leachate as it is magical stuff.
As an aside, I did once try a worm bin, but mine was a failure. The fruit flies were prolific and mine developed a stink that was otherworldly. Just awful. I gave up on the worm bin. I don’t regret it though, as my thoughts now are that compost should be in direct contact with soil where you plan to grow something. It might not be as tidy as a worm bin, but the microbes and other decomposers will work from the soil into the pile, and from the pile into the soil. It is a mutualistic relationship.
And I don’t put a lot of time or effort into making the pile. I just pile it up and what decomposes decomposes and what doesn’t I either spread around or use to make a new pile.
TL;DR: I say use that liquid as it is good stuff and don’t get too worked up about which decomposers made it.
I remember listening to a podcast interviewing a vermicompost expert. She mentioned the leachate/tea conundrum. Yes, The leachate is a viable fertilizer. But one that is slightly anaerobic compared to the rest of the bin. The problem is that if you have excess leachate, your bin is too wet which is why it becomes more anaerobic.
Balanced moisture is the goal, but swings in either direction dont equal failure, just less than ideal conditions.
I have also watched the Geoff Lawton video and while his method works well, he also ends up with a very wet, sticky, vermicompost. A consistency that can be difficult to work with.
I sell worms, bins, compost and compost tea. This doesn't make me an expert but I've dealt with many customers. I tell them to use the leachate at their own risk. Why? Because any kind of new experience is kind of like coaching fifth grade basketball. You can have the best information, pictures, everything and they will even nod their heads when you ask if they understand. Then the whistle blows and they all do whatever they want.
I would trust the liquid that came out of watering my bins because I have healthy bins. I wouldn't trust liquid coming out of an anaerobic, over-fed bin to be good for my plants.
I make my compost tea out of compost and non-tap water. My water company uses chlorimine instead of chlorine most of the year. The chlorimine does not off-gas so pond water it is.
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The only thing that concerned me about the Geoff Lawton video is that he appeared to be saying that he started with fresh manure in that bathtub and ran a bunch of water through it and used that for watering, but he didn't exactly say *what* he watered with it. Mulch holes near plants wouldn't worry me at all, but directly on plants or especially as a foliar spray would worry me because I don't understand why that water from fresh manure wouldn't potentially be contaminated with E coli. The rest, I agree, I wouldn't worry about, but E coli on fresh greens that might not get cooked, would worry me. My understanding is that an animal that has its own variation of E coli in its gut is a perfectly healthy animal, but its E coli transferred to my gut could make me sick. Maybe Lawton's had his tested and figures the population of E coli is low enough it's not a risk - I suspect it's much higher in poorly managed animals and I it sure looks from Lawton's videos that his animals are extremely responsibly managed. If people are only using veggie scraps and tree duff in their worm bin, again, I wouldn't worry. So what I'm saying is that someone selling the worms who doesn't know how well you will manage them or possibly what you might put into your worm bin for the worms to eat, would probably want to cover his ass.
This is what the debate is really about. If you have some greywater and use it immediately it's fine but if you let it sit in a huge tank for days/weeks and then open it you can tell it is bad and please don't water near the fence with me living next door or water some greens and feed it to me because it as gone anaerobic, stink and decease causing (not that "good aerobic" greywater is potable drinking water). Now that same scenario plays out with worm compost liquid. In fact some folks go the extra mile and say:
1) Add an airstone and and let the good microbes multiply over 24hrs for A++ goodness
2) Some say just pour water over the bag of compost and use it immediately for good enough B- 3) But what most people are saying don't pour water over it let it sit for days with no airstone aeration because you will multiply bad microbes that will stink and get things stink for a D-in microbes. Now yes in all 3 system they will have the same amount of dissolved Calcium and other wonderful minerals and it will have water for, which is vital in a desert situation. And it probably is better than doing nothing.
So if you had the choice would you you go for A++ or B- or better than nothing D- ?
Thank you for some great insight and replies. I am in complete agreement with what most of you said both about the decaying organic matter and the quality of leachate versus compost tea. Like Keith I do not claim to be an expert by any stretch, but I have figured out what works and what doesn’t to maintain maintain close to ideal worm bin conditions, proper moisture without too much, great ventilation even in plastic tubs, and working toward greatly increased castings output.
I plan on sharing my worm bin design in a future post and would hope that Keith with his entrepreneurial experience in the worm business would jump in when I do. Meanwhile I am out of town on business and will be having limited responses this week.
Hey there, I just wanted to chime in. We've had several different worm bins in the over a decade we've been worm farming.
We began with collecting the leachate and aerating it over night. A little bit on a houseplant here and there should be just fine.
Since we sold worm bins, I was concerned with the comments of clients that too much water was added to the worm bin, to create more of this leachate. So I removed that from our design. We no longer have a spout. We just monitor the moisture levels.
If it's your bin and your plants. You'll notice the difference.
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