February 2009

How Much Waste Can Worms Eat?

Here are a couple questions from Leslie:

hello, I started my bin about a month ago and I wanted to know two things-
how much kitchen scrap (in lbs? or kg..) can 1000 worms handle (in an approximately 2 ft x 4 ft bin) per week? Also, how soon before the worms start reproducing? I’m concerned about too little or too much intervention with the worms so any guidance is greatly appreciated. Thanks! -Leslie

Hi Leslie,
Those are really good question (some things a LOT of people are wondering about, I’m sure), but the first one is also a tough question to give a firm answer for. One of the challenges of vermicomposting is that there are SO MANY variables that can influence the success of your worm bin, and the overall health and well-being of your worms. As such, trying to come up with absolutes based on various calculations can be pretty challenging – at least for the average worm bin owner.

What you do with your waste materials (before putting them in the bin) ALONE can have a massive impact on the productivity of your bin. Obviously, if you add your wastes simply as they become available, without taking any steps to help the process along, you will end up with a bin full of undecomposed material pretty quickly.

If on the other hand you freeze your waste materials or let them age for a period of time, then blend them up before adding them, you will greatly speed up the process, thus effectively boosting the processing power of your worms.

The type of waste can also have a significant impact on the quantity of waste that can be added every x number of days. Tests using highly optimized professional flow-through reactors have shown that worms can potentially consume 4-6 times their own weight in food PER DAY! I should mention that these numbers are based on consumption of grocery store produce waste (similar to homeowner food waste, I would imagine), which is mostly water to begin with.

Is it realistic to think you will see similar abilities with your worms – not likely! My point is simply that the processing ability of worms can vary WIDELY, depending on how you maintain your particular system.

Some suggest that a good guideline is 1/2 worm weight per day. In your case, since 1000 worms on average weigh somewhere around 1 lb, an estimate of 1/2 lb of waste per day – or 3.5 lb of waste per week might not be a bad guess. I’m a little hesitant to even mention that, but hopefully you will take that recommendation with a grain of salt, based on what I’ve said above.

So what exactly DO I recommend?

Let the worms be your guide! Do everything you can to optimize the process, and carefully monitor your worms’ progress – especially early on. Start with very small amounts of waste (especially if you have set up your bin ahead of time with food), and go from there based on your worms’ ability to consume the materials. Obviously you don’t need to wait until every last morsel is gone from the bin. I would suggest creating several small food pockets (staggering the creation of these over the course of a given week should be helpful as well) and simply watching how quickly these pockets of food are consumed. Once the first pocket is basically processed, you can probably set up a new one (you would have a couple others on the go already), and so on.

Moving on to reproduction…

It is very common for worms to start reproducing VERY soon after being added to a worm bin – especially if conditions are to their liking. In fact, worms don’t even really need to reproduce in order to start depositing cocoons into the bin. Reproduction is basically a means of replenishing the sperm storage organ. Once the worms have sperm they can simply keep producing cocoons (using their own eggs) until it runs out.

Given the fact that you’ve had your bin for a month, I would think that there would be plenty of reproduction and cocoon laying in your bin by now. It might not be all that obvious – but rest assured, if the worms are healthy and vigorous you will almost certainly have cocoons and young worms in your bin.

Anyway – hope this helps, Leslie!
Thanks again for the great questions

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Manure as Worm Food…and More

Here is a rather lengthy email from Cher. She has some good questions, so I thought it would be helpful to post it (and respond to it) here:

Hi Bentley, I am very very new to this. Matter of fact just days. I live in AZ and The property we have is small and lots of rocks. Not good to have a garden when you have no soil ha!
Anyway I thought about raising some worms to sell as bait and if that didn’t go over very well I was still covered because I could use the compost /dirt. I have plans on hopefully growing some garden plants in tubs/buckets. So either way I felt like I couldn’t lose. By the way I have horses and I was reading on line that some grow their worms in horse manure. I do realize horse manure creates heat. And the worms do not like it too hot. So I was wondering what your thoughts were on that as far as using old manure etc or if you advise that at all since one place i read that the de worming medicine that you have used for your horse will come thru the manure and kill the worms. Even if it has been months since they have been de wormed?

I watched your simple but effective video of using two tubs for making a worm bin. Which by the way I did last night. I just don’t have the worms yet. You had advised to let set for 1-2 weeks. So another question here: if I go digging in the horse manure and I find worms can I use those? Or do you think it best to order right off some? Obviously i am trying to keep costs way down.

Oh another question ..sorry.. Can you freeze your scraps and then use them for food? Like right now I have my left over broccoli, coffee grounds and Cucumber peelings etc frozen in freezer…good idea or bad?

We have some pallets that My husband said he would help me make some ‘farms’ out of. But they are for outside. I have your tub bin worm farm in my kitchen right now. Oh I appreciate your sense of humor too. Anyway if you have time and want to answer my questions that would be great. Need all the help I can get.
Thanks Cher

Hi Cher,
I really like your approach/philosophy re: the start up of a potential worm business – it’s always a great idea to cover the bases and not put too much on the line before you’ve tested the waters. With that sort of attitude, and your current situation (owning horses etc), I think your chances of finding success are quite good!

Moving on to your questions…

Aged manure is pretty well the ‘ultimate’ worm food, so I definitely recommend using it – at least as far as large-scale, preferably open (no lid) systems go. i.e. I would definitely use caution when it comes to adding manure to small indoor worm bins – very important to make sure the material is really well-aged, since harmful gases (namely, ammonia) can be released during the decomposition of this material.

If I had horses (I WISH!), I would probably make a big outdoor pile of manure and bedding (straw etc) and just let it sit for awhile. I would continue to add new material, but likely only on one side. Eventually (maybe after a few weeks), I would add composting worms to the side with the oldest material.

Some of the craziest densities of composting worms I’ve ever seen have been in aged, outdoor manure heaps. As for the de-worming medication, it should get broken down as the manure composts/ages, so generally this shouldn’t be an issue by the time you add the worms. You can always test thing out on a small scale ahead of time just to be safe.

As for using worms already in your heaps – I’d only recommend relying on these IF you know for sure they are composting worms (eg Eisenia fetida). I’ve seen plenty of regular soil worms in old manure, so there is no guarantee that worms you find in your heaps are the right ones. If you DO see high densities of smallish, reddish worms, you are likely in luck!

Freezing food wastes is actually one of the best approaches to take – it greatly speeds up the decomposition process since it breaks down the structural integrity of tough plant (and other) materials, thus making the wastes far more accessible to microbes. Chuck these frozen wastes into your aged manure heap (once worms are established) in the middle of the summer and see what happens!
FEEDING FRENZY! (once they’ve thawed out, of course)

Hope this helps!

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Using Putrid Worm Tea

Here is a question from Debra:

Good AFternoon,
I am relatively new to the vericomposting craft. I just love the
ideal of making use of all that we are blessed with. My Grandmother
used to tell me “waste not…want not”.
Anyway, I have a vericompost bin set up (approximately 5 months now).
I have been harvesting the liquid; keeping it in gallon jugs until
Spring. I live in the Pacific Northwest and we have some pretty
extreme temps during the winter. I’ve noticed a very strong smell
from the liquid with a thin film on top. I am assuming that this
indicates anarobic (the bad bacteria) growth. Can I use this liquid
with the bad smell; should I try to airate it with air stones before
use? I don’t want to harm any of my precious plants come spring time.
But I also do not want to discard something that I could make usable.
Thank you for your website and your words of wisdom. We, in the
field, appreciate all you do!

Hi Debra,
Interesting question. In all honesty, I definitely wouldn’t put worm bin leachate in bottles and just let it sit for months – the potential for it becoming a putrid mess is pretty high!
I hate to recommend getting rid of ANY potentially useful resource though (remember – even ‘wastes’ are just misplaced resources), so I certainly wouldn’t tell you to just chuck it.

Bare minimum, you really should dilute it and start aerating it well before trying to use it. Use your nose as a quality tester – as long as it has any bad odor you definitely don’t want to use it. Even once it is fairly odorless, I’d still recommend using it with caution – maybe pour some in an area of your garden you aren’t all that concerned about. Or simply pour it on some weeds – who knows, maybe you’ve invented the ultimate weed killer and don’t even know it! (just for fun, maybe you could try out the pure, unaerated stuff and see what happens)

Once it looks as though it’s not going to harm your plants, you can probably get a little more bold with your use of it.

Hope this helps!

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Does Vermicompost Go Bad?

Here is an interesting email from Crissy:

Quick question about the use of vermicompost – does it go
bad, and if so, how do I know not to use it?

I harvested my worm bin for the first time back in October, which was
just before the rain started here. The compost was pretty wet, but
for the most part smelled like rich soil. I’d planned to let it dry
outside a bit, then store it in bags or jars and give it to my
gardening friends, but I misjudged the weather. It’s been sitting
outside in a big, fairly shallow plastic flower pot, loosely covered
with a tarp ever since.

I’ve decided that I want to give container gardening a shot this
year, and want to amend some old potting soil with the vermicompost.
I just want to make sure that it’s still okay to use before I get
everything planted.

Hi Crissy – that’s actually a great question!
I’ll start by saying “it depends”. What it depends on is how stabilized your vermicompost is. By definition, vermicompost is a ‘humus-like’ end product that results from the stabilization of organic wastes (thanks to the joint effort of worms and microbes). Humus is a highly stable material – very resistant to further breakdown. As an analogy, consider peat moss – or potting soil (which usually contains a lot of peat moss). If you soak brand new peat moss and let it sit indefinitely, it will never go ‘bad’ or decompose much further than it already has. This is the same idea with really good quality composts.

If there is still a fair amount of partially decomposed waste materials left in your vermicompost, there is a decent chance that these could rot further – and if this occurs under anaerobic conditions, you could end up with a material that is considered ‘bad’. In other words, it is basically the anaerobic breakdown of unstabilized organic wastes that results in nasty smells and the foul nature of ‘rotten’ materials. Believe it or not, if you ground up fresh chicken meat (an example of a material that would be really nasty if rotten) and mixed it with a LOT of peat moss or some other bedding material (along with some mature compost for good measure) and provided the mixture with a LOT of oxygen, it would compost just like anything else.

Farm animal mortality composting is actually quite common. It is next to impossible to eliminate ALL anaerobic microsites in a mixture, so there could still be some odors – but its amazing what you can do when you add enough bedding and provide enough oxygen.

Anyway – I’m getting sidetracked here.

Good vermicompost should keep for quite some time (sometimes years) – and it really only loses its potency, rather than going ‘bad’. If it is sitting outside, exposed to the elements, the quality can degrade quite quickly – but if covered up, it should be totally fine for at least multiple months.

It certainly won’t hurt to use it, either way (again assuming it is good quality stuff to begin with). Just mix it up and take a whiff. If it smells rotten, mix it some more then put it somewhere dry to sit (on top of multiple layers of corrugated cardboard might help to draw out excess moisture). It should eventually become aerobic (with the rich, earthy smell of good humus), and useful as a soil amendment.

Hope this helps!

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Grains for Worms

Here is an interesting question from Ruthie:

my husband and i are new to worm farming and have read just
about everything i can find regarding food for the worms; we have a
“cultured” nightcrawler which we are going to use for castings and
fish bait; i have seen the mention of grain feeding and would like to
know which grains would be best? what ratios to use etc. there has
been a mention of rye & barley?

would appreciate any information you can supply me with.

Hi Ruthie,
I’m not really an expert on this topic, but my hope is that by posting this on the blog we’ll get some comments from readers who do use a lot of grain foods for their worms.

I honestly think a lot of grain products would work well. I’ve heard that a lot of people use chicken ‘laying mash’ as a worm fattener, but have not tried this myself. I’ve used wheat bran mixed with food waste slurry (my homemade manure), but it’s hard to say how effective it was given the fact that it was mixed with a lot of other materials.

I’ve also used brewery wastes (which, according to some experts is an excellent material for worms) but actually found them very difficult to work with – they went anaerobic (and nasty) very easily and the worms didn’t seem to care for them at all.

You mentioned culturing ‘nightcrawlers’ successfully – I would be interested to learn what type of nightcrawlers you are referring to. I have yet to come across someone who has had a lot of success with soil nightcrawlers (such as the Canadian Nightcrawler – Lumbricus terrestris), given their requirements.


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More on Small Winter Worm Bins

Worm Bin Heater

I received a cool email from RWC reader, Christy – who wanted to share with me her winter worm bin set-up (after she saw the recent post about building a small winter bin). I asked Christy if I could share her info/photos and she was more than happy to oblige.

Here is what she wrote:

I saw your latest post about a worm heater and I thought I would give you pictures of the heater I set up in my parents worm bin. Their bin is sitting in their unheated Rabbit Barn. The barn has dropped below freezing several times (once for almost a week) but the bin has stayed above 65 degrees on the heated end.

The Heater is really simple to set up. I used a one gallon glass jar and a 2 – 5 gallon aquirium heater. The total cost is less than $10.00. I filled the jar with water and cut a hole in the lid for the cord. I place the heater in the jar according to the directions. I use an aquirium thermometer to check the temp. of the jar. It stays between 72 – 76 degrees. The jar is barried directly in the bin and placed close to one end to allow the worms a place to go if the heater gets too warm. The worms have stayed very active all winter even during very cold spells. The bin does dry out a little around the heater but it is easy to mist the area every few days.

Worm Bin Heater

Thanks again, Christy – this sounds like a nifty system!

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Winter Worm Composting – 02-23-09

Compost Thermometer
Nice and toasty warm in parts of the winter worms bed

Just a quick update on the winter worm composting front. I popped by my dad’s place on Friday to see how things were doing in the outdoor bed. He had been providing me with encouraging temperature updates (you may recall that we buried the sensor for the remote weather station in the bed last time), but I wanted to check temperatures throughout the bed.

I also wanted to add a considerable amount of food waste that had been piling up at home. I originally started stockpiling it so that I could make some ‘homemade manure‘, but the time involved (and the fact that my blender seems to have gone missing – I suspect foul play! haha) made me decide to simply take it over to my dad’s. Unfortunately I didn’t have enough time to add it to the pile on the day I took it over, so it was frozen when we added it on Friday.

Food Waste Added to Winter Worm Bed
Lots of frozen food waste added to the top of the heap before being covered in straw

This actually makes things a little more interesting, since I’ll be really interested to see how/if it affects the overall bed temps, and how quickly it becomes worm food. One thing to point out – if you are wondering why there are plastic bags mixed in with the food waste, it is because these are made with biodegradable plastic.

Temperatures in the worm bed seem to be even higher than when I last checked, but certainly aren’t off the charts (always a good thing). The lowest temperatures I found were in the 10 C (50 F) range, while the highest was about 30 C (86 F).

Lots of worms seem to be really active up near the surface – I actually ended up feeling badly about the fact that I was digging around at all (to look for worms, and to create a bit of a depression for the food waste), since it was brutally cold outside at the time. My dad and I were more than happy to quickly pack it in and head inside after the food waste was added!

I will more than likely head over this Friday to see how things are looking.
Stay tuned!

Previous Winter Worm Composting Posts

Winter Composting Extravaganza 2.0
Winter Worm Composting – 12-08-08
Winter Worm Composting – 12-15-08
Winter Worm Composting – 12-30-08
Winter Worm Composting – 01-23-09
Winter Worm Composting – 02-09-09

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