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vermicompost windrows question

Posted by advait India tropical (jaiamma@gmail.com) on
Tue, Jun 17, 14 at 8:21

Hi,

Here's some background and my question is at the bottom. I help to manage a 3,000 sqft vermicompost facility (VCF) in Kerala, India and I'm new to the world of vermicompost. We use simple windrows about 20 inches high and 36 inches wide. At another nearby location we have a thermophilic compost operation (TCO). They have a rotating screen filter to filter the compost piles (which are actually mulch piles with very little finished compost inside). The TCO piles are made from food waste and lots of carbon materials like wood chips, shredded leaves and sticks.

The smallest filter mesh size is about 5mm. The fine mulch that falls out of this is used to make the VC windrows. We let the worms (esenia fetida) work on the windrows for about 3 months or so. When we collect the worm castings the bottom 3 or 4cm of the VC piles is uneaten by the worms. We take that uneaten bottom material (UBM) and put it on top of other VC piles and the worms finish it off. In addition to daily watering, about every 3 or 4 days we pour cow dung slurry on all the VC piles and then stop feeding and watering about 12 days before collecting.

A friend of mine who has studied worm composting says that the UBM can be considered finished vermicompost. That surprised me. When I look at the UBM its just small pieces of undigested wood (sawdust size up to 5mm). My understanding is that undigested wood cannot be considered compost since it would attract bacteria and be a nutrient "sink" in the soil.

Now I want to get some expert opinions. Can the UBM be considered as finished vermicompost? Low quality vermicompost? Or not vermicompost at all but just a rich fine mulch?

Let me know if you need any other details. Thanks! Kind Regards,

Advait


Follow-Up Postings:

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RE: vermicompost windrows question

Not an expert here, but I have some experience with windrow and outdoor vermicomposting. I find your post quite interesting.

I think it is a matter of terminology. Worm castings are different than vermicompost.
Castings are just that...worm casts, which is the material digested by worms. The casts are the small fine black pellets.
Vermicompost is a combination of all material in a worm bin. It usually contains large amounts of castings along with some partially decomposed (unfinished) material.
To me, vermicompost is unfinished worm castings. Finished vermicompost is a term not often used and open to interpretation.
I do not know about the undigested wood attracting bacteria and being a nutrient sink. I don't add wood to my beds. I do like vermicompost better for my amending my very fine soil. I prefer castings for teas, starter mix, and top-dressings.

I would suggest continuing the operation as currently run. UBM probably helps get the new row to start breaking down quicker.

Out of curiosity I have a few questions.
What is the initial stocking rate for the windrows?
How do you harvest/ remove the worms?
Do you cover the windrows? Do you keep them dark and safe from vermin?
What do you do with the product? How is it used?

I hope this was of some help. Thanks for posting and good luck!


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RE: vermicompost windrows question

Just posting to get notification emails. Very interested in this.

Paul


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RE: vermicompost windrows question

Are you able to get food waste without plastic and silverware? How is that removed?

I think we all want to go on a vermicomposting group tour to India now.

mendopete's answers look great to me.

Is the person that designed the system there to ask questions of?


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RE: vermicompost windrows question

Hello mendopete,

Thanks for your reply.

'I do not know about the undigested wood attracting bacteria and being a nutrient sink.'

My understanding is that undigested organic material (wood, leaves, dead bugs, etc) attracts bacteria. The multiplying bacteria soak up the surrounding nutrients in the soil while they digest the material. Once the material is digested, then the bacteria die and their nutrients become available to roots, etc.

The top 60% to 70% of the oldest piles is mostly castings, so its pretty pure and high quality. The UBM is mostly small pieces of wet undigested wood. My intuition is that the UBM is great mulch but should not be considered finished compost - that's what I'm researching.

'What is the initial stocking rate for the windrows?'

We harvest the vermicompost and worms from the oldest windrows (about 3 months old). The separated worms are then put onto the new piles. We're continually harvesting old piles and making new piles.

'How do you harvest/ remove the worms? '

Currently its all done manually. We have a system where one person can remove the worms (harvest) from about 40kg of vermicompost in 2 hrs. In the near future we hope to get a slow rotating screen mesh filter machine to more quickly separate the worms from the worm compost.

'Do you cover the windrows?'

No. The windrows are in a roofed open shed with a concrete floor. The roof is good so no cover is needed.

'Do you keep them dark and safe from vermin? '

The shed is open so its bright during the daytime, but the windrows never get direct sunlight due to the good roof. We feed the worms cow dung slurry every 2 or 3 days and that seems to do a very good job of repelling rats and mice. We don't feed the worms anything else. The worms like the slurry but their main food is the fine filtered mulch.

'What do you do with the product? How is it used?'

The vermicompost is used at our large campus here which has many gardens. Some of it also goes to local farmers and to coconut tree orchards. Kerala is wall-to-wall coconut trees. Billions of them!

More details on our vermicompost operation is at our website amrita-earthworms dot info. It's a totally non-commercial web site. Let me know if you would like any other details.

Thanks again for your replies. Kind Regards,

Advait

Here is a link that might be useful: Our vermicompost info page.


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RE: vermicompost windrows question

I like your operation, advait!

It's a bit 'intensive' with the concrete slab, rim wall, and shed, but it's not what I would call "industrial" either. Should be easy to do for a "cooperative" or someone very serious about their personal worming operation.

I would caution you regarding "theoretical" concepts that are supported primarily by "research" and not "real life". My point being the nitrogen and other nutrient "sink' that undigested wood might represent. There is no doubt that someone has demonstrated "scientifically" that undigested wood "attracts" bacteria that in turn "use" nutrients - particularly nitrogen. That is "scientifically" "proven". However, as an example of how science is SO often mis-applied, consider the following: Throughout the world agricultural community, it is WIDELY acknowledged that crop rotation is practiced FOR THE PURPOSE OF INTRODUCING NITROGEN-FIXING BACTERIA INTO THE NITROGEN-DEPLETED SOIL. I would urge you to use the "data" regarding nitrogen "starvation" VERY cautiously. Consider the nitrogen 'flooding' you are providing with the cow, pig and other mammal dung slurry you are providing. There is no shortage of "free" nitrogen in your system.

In addition, individual bacteria don't live for years. When one bacterium dies, all of the nitrogen it "fixed" will be available to the "system". Just as millions of bacteria are produced per unit time, so are hundreds of thousands dying. This is the foundation of the REAL LIFE concept of crop rotation with plants that encourage nitrogen-fixing bacteria.

Regards,
Paul


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RE: vermicompost windrows question

Thanks for the "tour". That is a nice worm facility.

UBM could be called vermin-mulch!

Good luck
Pete


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RE: vermicompost windrows question

[[Hello equinoxequinox, My replies below in brackets.]]

Posted by equinoxequinox (My Page) on Tue, Jun 17, 14 at 13:11

Are you able to get food waste without plastic and silverware?

[[Yes]]

How is that removed?

[[The people here at our campus are trained to put only food waste in the food waste bins. By and large they do a pretty good job, so we only need to remove a small amount of non-bio waste out of the food waste.]]

[[And in any case, none of the food waste goes to the worms. The worms only get filtered mulch (like a course saw dust) and cow dung slurry.]]

I think we all want to go on a vermicomposting group tour to India now.

[[ (smile!) You're welcome to visit any time. Our campus is right on the ocean and we have millions of palm trees. Very beautiful.]]

mendopete's answers look great to me.

Is the person that designed the system there to ask questions of?

[[I inherited the vermicompost system 2 years ago when it was much smaller. I've changed it quite a bit so I guess I'm the system designer. I'm doing internet research and contacting various forums and experts to understand the finer points of vermicomposting. The trick is to find time to do the research. We currently don't have enough labor here so I'm pretty busy all the time. But I get a few moments here and there to post some questions on the vermi forums. In a few months we'll get more labor and I plan to do a lot more research then. And I'm learning some great stuff from this forum.]]

[[Cheers! -Advait]]


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RE: vermicompost windrows question

[[Hello Paul pskvorc, Thanks for your reply. My replies below in brackets.]]

Posted by pskvorc 3 (pskvorc@biopar.com) on Wed, Jun 18, 14 at 12:43
I like your operation, advait!
It's a bit 'intensive' with the concrete slab, rim wall, and shed, but it's not what I would call "industrial" either. Should be easy to do for a "cooperative" or someone very serious about their personal worming operation.

[[Our vermi compost operation will get more industrialized once we get our rotating worm harvester machine. That will allow us to separate out the worms faster with much less labor.]]

I would caution you regarding "theoretical" concepts that are supported primarily by "research" and not "real life". My point being the nitrogen and other nutrient "sink' that undigested wood might represent. There is no doubt that someone has demonstrated "scientifically" that undigested wood "attracts" bacteria that in turn "use" nutrients - particularly nitrogen. That is "scientifically" "proven". However, as an example of how science is SO often mis-applied, consider the following: Throughout the world agricultural community, it is WIDELY acknowledged that crop rotation is practiced FOR THE PURPOSE OF INTRODUCING NITROGEN-FIXING BACTERIA INTO THE NITROGEN-DEPLETED SOIL. I would urge you to use the "data" regarding nitrogen "starvation" VERY cautiously. Consider the nitrogen 'flooding' you are providing with the cow, pig and other mammal dung slurry you are providing. There is no shortage of "free" nitrogen in your system.

[[I hadn't looked at it that way. I think you're right on target. The UBM from our piles have been soaked for two months or more in cow dung slurry, so I think you're correct that is has lots of nitrogen. So even when bacteria appear to eat the wood, there may be plenty enough N around for the bacteria and any nearby roots. That helps me understand the process better.]]

In addition, individual bacteria don't live for years.

[[Yep, I think they only live for a day or so...? Something like that.]]

When one bacterium dies, all of the nitrogen it "fixed" will be available to the "system". Just as millions of bacteria are produced per unit time, so are hundreds of thousands dying. This is the foundation of the REAL LIFE concept of crop rotation with plants that encourage nitrogen-fixing bacteria.

[[I'm in the process of locating some nearby soil testing labs. Then I'll test the UBM for NPK, C/N ratio and some other parameters. That will tell me if the UBM is more of a mulch or more like finished compost. Then we'll know how best to use it. I assumed the UBM was just a rich mulch but I need to do the tests to see what it really is. And we also plan to use the UBM in some potting soil mixtures with seedlings to see how they grow. I love doing experiments! Thanks for the great info.]]

[[Cheers, -Advait]]

Regards,
Paul


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RE: vermicompost windrows question

I don't at all consider myself an expert, but I would still overall go with what Paul says and your own instinct.

What others say about what is 'finished' is irrelevant - what really matters are your own uses for your compost and whether it's finished 'enough.' And whether the current process of 'recycling' the bottom layer - let's call it the 'less finished' layer - works better for you compared to the alternative.

Experimenting is the only way you'll be able to tell and decide based on your uses, needs, and the labour involved.

In short, it's perfectly okay if some composting/decomposing happens in the ground / when applied. If mixed with some other compost (VC or otherwise) and maybe some of your cow dung slurry, it would probably happen quickly, especially if not applied in huge amounts in one place. (I would guess that any nitrogen impact to having a bit of extra carbon would be marginal unless this was large amounts and not mixed with other stuff - but just a guess)

Then it depends on whether the mix you're using works with the plants and conditions you have. In the end, all of it is going to be organic materials/soil amendments.

Of course, it also doesn't sound like the current 'recycling' of the less finished stuff is that big a problem, either.

And a side note: all the definitions/descriptions I've read of 'finished' compost just refer to a relatively stable mix - i.e. there isn't much more decomposing going on, but there's always some. So does it make much difference if it's 20% or 10% or 5% (made-up numbers)? Maybe in some applicaitons, but farmers till in plant residue all the time.

I also think that some 'roughage' may be useful in soil. As long as your use is not a beauty contest for who makes the prettiest and most uniform worm castings.)


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RE: vermicompost windrows question

Hello armoured,

Thanks for your reply. Another person involved in our worm compost project seems to think that the UBM can be considered as finished compost but it certainly looks like mulch to me. So I want to be cautious mixing the UBM with the finished vermi-compost. The UBM could cause problems with the plants and then people will come to me asking "What's wrong with your vermi compost?" Finished compost can be used in potting soil and can get mixed in with soil around the roots. Mulch (even rich organic mulch) should not be used like that. I know there's lots of variables and exceptions, but in general that's my understanding. So my next task is to locate a soil test lab and get some hard data on what the UBM really is. And I'll do some seedling experiments with the UBM myself. The farmers and gardeners here won't do such experiments. They'll just use it. So I want to have good confidence that when we deliver finished compost it really is finished. The test lab data will help determine that.

In the meantime, I wanted to also get the views of others on this forum who have more experience with vermi composting than me. Your insights have helped me better understand some of the subtleties about vermi-compost.

I'll post the test results here once they're completed. Thanks to everyone! Cheers,

Advait


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RE: vermicompost windrows question

Advait, your approach sounds right to me, and since your VC is used by others you don't want to change it without being sure. Particularly since your current approach seems to be working.

I also didn't/don't know much about your specific application. Use for seedlings etc might be a lot more sensitive to potential issues, and timing more critical.

I was referring (broadly) more to use as soil amendment with more mature plants. I'm also in a cold climate where (for example) it might be more normal to apply semi-finished/mulch in fall, where the finishing would happen during the non-growing season. (Not that I really have any idea whether my approach is normal, and I'm not growing anything commercial). So caveat lector!


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RE: vermicompost windrows question

[[Hello armoured, My replies below in brackets.]]

Posted by armoured (My Page) on Fri, Jun 20, 14 at 3:51
Advait, your approach sounds right to me, and since your VC is used by others you don't want to change it without being sure. Particularly since your current approach seems to be working.

[[I'm pretty sure the top of the vc windrows are excellent finished vc. So I'm pretty confident it can be used with success.]]

I also didn't/don't know much about your specific application. Use for seedlings etc might be a lot more sensitive to potential issues, and timing more critical.

[[You're correct. Seedlings will be more sensitive and (I think) a good way to get an intuitive feel of how seedlings are affected by the different types of vc and "vermi-mulch" we produce. The more experiments the better. Good farmers are always experimenting because there's so many variables.]]

I was referring (broadly) more to use as soil amendment with more mature plants. I'm also in a cold climate where (for example) it might be more normal to apply semi-finished/mulch in fall, where the finishing would happen during the non-growing season. (Not that I really have any idea whether my approach is normal, and I'm not growing anything commercial). So caveat lector!

[[I'm pretty sure the UBM (the uneaten bottom material in our vc windrows) is a totally excellent mulch and soil ammendment. I need to do some lab tests to see if it could also be considered a finished or semi-finished compost. I think I've now located a good testing lab. Thanks for your replies.]]

[[Cheers, Advait]]


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RE: vermicompost windrows question

Paul your explaination of what happens as material decomposes in the root zone of plants is the best I've heard and I have heard many because it comes up about twice per day, armourd,you real life example of crops planted in residue should seal the deal for those who panic over random pieces of material in their compost and are afraid to use it. Tip hat to both of you, I hope many read and digest the information then apply it.


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RE: vermicompost windrows question

Do you have, or want to learn to use a microscope ?
Did you sign up to receive email replies & your email address
so we (I) could send an attachment ?


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RE: vermicompost windrows question

Does an outdoor windrow have a containing bottom ?
(Does the question make sense ?)


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Search result:

I think you want to make a "vermi-trench". Basically dig a trench down the middle of your raised bed. Make it a shovel width wide and about 18" deep. Add a layer of thick cardboard, some worm food, worms and cover with straw. Pull back the straw and feed every week or two. After the growing season you could add horse manure or garden scraps and lots of straw to help winterize your wormery.

Thanks Pete.

And I read that your rows don't have bottoms. Is the cardboard on the bottom of the "vermitrench" ?


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