Largescale Manure Vermicomposting

Big Manure Pile
Horse manure (with bedding) pile – prime time Red Worm real estate!

Here is a question from Brent:

I was wondering if you had any info on system design for
composting horse manure? We usually have 3-4 horses on site and I am
currently composting teh manure/shavings mixture. The process take a
few months and I suspect the worms would be faster and more efficient.
Let me kow if you know where I can get info on larger systems and
managing these to take care of my manure. Thanks!

Hi Brent,
Great question! I’m certainly not a ‘design guy’ by any means, but I do have some thoughts to share on this topic. For starters, let me say that you are absolutely right – adding composting worms to a manure composting system should GREATLY speed up the process. I know I am a tad biased here, but I would also say that it will result in a vastly superior product as well – and technically TWO products, if you count all the worms you’ll be growing!

I would never suggest that you completely skip the ‘regular composting’ stage however – in fact, when you are working on a large scale with manure, implementing some sort of ‘pre-composting’ stage will be really important. It will help to rid the material of weed seeds and pathogens (research has shown that vermicomposting effectively removes pathogens as well – but never hurts to be extra sure!), and will also remove a lot of the heating potential and excess ammonia, both of which can lead to dead worms in a hurry!

There are multiple approaches you can take as far as the design of your system goes – what it comes down to is asking yourself how seriously you want to get into this? If you have plans to sell the worm castings (vermicompost), then perhaps you will want to invest some serious money in a fancy continuous flow system (more on that in a minute). On the other end of the scale, if you simply want to reduce the volume of manure on site, then maybe you will be ok with some very basic approach.

On the basic end, you could literally just pile up the manure, let it sit (and heat up) for a period of time then add composting worms to it. Some of the most incredibly successful populations of Red Worms I have ever seen have been living in old manure heaps. The downside of this approach is that it doesn’t really offer you a good way to separate out the worm compost – especially if you are continuing to pile up more fresh manure on it.

Another low-tech approach which can be VERY effective is what’s known as the “wedge” system. In essence, I am talking here about a ‘souped up’ manure pile that is then simply extended into a windrow (or multiple windrows). If you have the space for this and don’t feel like spending big bucks on an actual system, this is definitely the route I would recommend taking!

In a nutshell, you would start with a relatively small pile (or piles) of manure – material that has already been ‘precomposted’ for a week or so – and add to it a few pounds of Red Worms (Eisenia fetida). Let the worms work this material for another week, then start adding new material to one end of the heap. Over time you will end up with windrows, and the beauty of this approach is that the worms are going to follow the end with the newest (highest quality) food material. Eventually (exact time will depend on how quickly you are extending the windrow), the material back where you started will be nice worm compost, with relatively few worms and cocoons – obviously, the longer you make the windrow the more mature this material will be.

If you are planning to market the finished compost, you may want to do this indoors, or at least under some sort of canopy to help prevent rainfall from removing some of the potency of your castings. The size of the windrows would be up to you – it is important that they are manageable however. Perhaps 3-4 feet in width and about 3 feet in height (length would simply depend on the amount of room you have).

Moving on to a more ‘high-tech’ approach…

If you DO have the dollars and the desire, you may want to go all-out with this and do something similar to the guys at Worm Power. In other words, build (or have someone build for you) some type of continuous-flow vermicomposting system. Here are a couple of interesting YouTube videos about Worm Power to give you a bit better idea of what I’m talking about:

I suspect that given the details you provided me with regarding your current situation, this approach might be a bit more than you would be interested in, but it’s always good to know what possibilities are out there!

Anyway – I hope this helps, Brent! The bottom-line is that I definitely recommend you get into vermicomposting, since you have access to a material that Red Worms absolutely love. Not only will they help you to reduce the volume of your manure, but you will end up with an abundance of top notch ‘compost’ (although I hesitate to even call it that), along with countless worms that can be sold or used in other worm composting systems.

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  1. Good Morning, Bentley…
    It happens that my other passion, besides organic gardening and raising worms to accomodate that, is Thoroughbred racing. Right now, with the economy, horse breeders are having a pretty tough time. I have been explaining, on a large TB online forum, the opportunity they have with vermicomposting and their waste. I put the link to your great blog here on their forum and hope to entice some horse breeders to consider vermicomposting. Some regional breeders might even want to work together to create a side business with their vermicompost product? When life gives you horse manure, make vermicompost! Yeah, that’s your bad worm joke of the day.

    • Bentley
    • September 16, 2009

    Wow, Heather – sounds like you have a great combination of hobbies! 🙂
    I’ve always thought that a really cool business idea would be to buy a boarding stable then create an associated vermicomposting and organic gardening operation – so basically three different sources of income! It’s great that you are trying to sell this to the horse people. Lots of potential there.
    Love the joke, by the way!

    • jeff
    • September 16, 2009

    I do work wiht several small farms, mostly cattle. To help speed up the pre-composting I recomend doing a passive aeration system. What that comes down to is putting some pipes with holes drilled into the sides in the windrow. This will greatly increase the amount of air that gets into your system pile. As you progress just pull a pipe from the start and put it under the new manure.

    Good luck
    Monmouth Worm Man

    • Brent
    • September 18, 2009

    Bentley-Thanks for the excellent info. I hope to begin experimenting with this system soon. If anyone has ideas on suggested system design (other than the pile system), please post as I would be very interested in learning more about larger scale systems. I currently use the O2 compost system for my horse manure but have trouble keeping up with the volume due to the time it takes to decompose/compost the manure. The worms sound like they will greatly increase the speed of the process and give me a better product when finished. Thanks again for the valuable info!

    O2 Link:

    • Bentley
    • September 18, 2009

    Hey Brent – that is really interesting that you use the O2 system. This is an excellent way to precompost your manure for further vermicomposting. I am pretty sure Jack Chambers (Sonoma Valley Worms) is using the O2 system before adding the manure (dairy cattle in his case) to his multiple flow-through beds. I highly recommend you contact him (look for link to Sonoma Worms in left hand column under ” worm friends”) – he is a great guy, and has lots of experience with all of this.

  2. Brent, it might be worth it to look into Black Soldier Fly larvae too (depending on where you are). While they don’t make great compost, they do reduce manure at a prodigious rate. And then they make great chicken, fish or lizard food.

  3. Hi Everyone Great site.

    I use fresh horse manure and love the system I have built. I am preparing to build my next one the same way also. I Live in Reno NV, so this system keeps my worms eating during the winters.

    Check it out

    • Bentley
    • September 25, 2009

    DARREN – thanks for sharing your site! That looks like an AWESOME system. The fact that you are having so much success in such a harsh location is really cool! I’m going to mention your link in my next newsletter.

  4. Thanks Bentley

    Any publicity is good. I did not go into much detail and would be happy to answer any questions that your guests may have.

    Happy Worming


    • Bentley
    • September 25, 2009

    If that wasn’t much detail, I’d love to see your long-winded articles!

    Seriously though, we’d love to learn more, and as I wrote in this week’s newsletter (just sent out), it would be cool if you could write a guest post on the blog or take part in an interview for the site. I will fire you an email about this now.

    • Vijay Tonse
    • November 11, 2012

    I notice that one of the respondents has mentioned use of the Black Soldier Fly Larvae to deal with the manure.

    There is plenty of information on the internet on this subject, but here are some immediate facts:

    (1) Black Soldier Fly Larvae (BSFL) will convert 100 lbs of organic wastes ( including various manures ) into about 5 lbs of castings and about 18 to 20 lbs of edible larvae ( grubs ) which can be fed to a variety of animals ( fish, chickens, pigs, reptiles, wild birds etc ) all of which will relish these grubs, at superfast speeds way ahead of any worms.

    (2) The BSFL castings make excellent food for earthworms, especially the Red Worms, maybe others too.

    (3) The liquid leachate from the larvae bin is excellent for plants if used in the right way ( it is acidic ).

    Vijay Tonse

    • Kevin Lane
    • March 6, 2013

    Darren: Absolutely awesome site and process and similar to what I would like to set up here just outside of Buffalo NY (Orchard Park, where the Bills play like worms anyhow). I have some questions

    1. Did you do anything special to winterize the bins for the worms aside from covering the bins with plywood?
    2. Looking at the photos of the bin it appears that you have two areas, one empty and the second with material in it. Only one section of this material appears to have “food” on it, and that spot moves further from the first part of the bin as the worms do their thing.
    a. Is the food “bottom to top or is it instead piled atop bedding? What bedding is used?
    b. If you did not seed the area do you think that worms would have naturally colonized it?
    c. Suppose you placed food material within the entire 150 foot bin and then seeded spots at a certain distance from one another, say three feet. Would that result in more rapid conversion to vermicompost of the entire row?
    4. How long is the feeding area and how long does it take the worms to devour it?

    Sorry for being too wordy here but I love what you have done. Many thanks for any information that you can share.


    • Esme
    • August 13, 2013

    What system can I use to capture the worm tea? I have 4 horses and cows and collect a neighbors hirse manure too. I have billions of red wrigglers but my compost piles are on the ground. Now I want to find a way to get the worm tea but on a large scale. Hoping for something that we can build ourselves to save on costs

    • Marty
    • February 14, 2017


    I’m no expert but I’ve been told that if you have worm tea then your worm bin is too wet. What I recommend is that you keep doing what you are currently doing and make compost tea which your plants will love (or you can even sell it. I sell small bags of castings and gallon jugs of tea at flea markets.) I’m retired so this provides me with extra cash to do the little things around our Miniature Horse ranch (miniature horses not a miniature ranch).

    Hope this helps,


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