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please help with "math"

Posted by barbararose21101 8 (My Page) on
Sat, Jun 21, 14 at 12:09


According to this study, worm density affects reproduction.
I'd like to figure out how worm-dense my bin is.
(I know it is not dense by common sense.)

For instance, if you started with 5 kg of worms and put them in a bin
with a surface area of 2 m2, then your initial stocking density would be
2.5 kg/m2.

5 kg = 11 lbs & a fraction of an ounce ?

2m squared ? 3 and a quarter feet ? x 3.25 = +/- 10.5 sq ft ? (area)

my bins are 13.5 x 19.5 inches (area).

If I round up and down how far off will I be by calculating 1 foot by 2 ft = 2 sq ft ? which is about a fifth ? of the example ?
So would you put 2 pounds of worms in a 2 sq ft bin?

Follow-Up Postings:

RE: please help with "math"

If I read the manual correctly, it said stocking rates greater than 1lb/sq.' begin to slow the reproductive urge. It suggests starting with 1/2lb/sq.' and splitting the bin when it REACHES 1lb/sq.'. This would be to maximize reproduction and grow the herd.

It is hard to get worms to answer roll call. A few years back I did a "census" by removing 1sq.' of a dense bed. I did a light sort and then measured 5 cups of worms. 1 lb of worms = 2 cups, so it had about 21/2 lbs/sq.'. Most all worms were adults. They must have slowed or stopped breeding. I now have a better idea of density by looking and poking around the bed.

bin density

That helps. Thanks.

Decisions. Decisions.

RE: please help with "math"

**Except in a couple of specific situations (which we will be talking about later), if they are given adequate food and fresh "bedding" material, worms do not appear to be bothered by "overcrowding."**
I got this from:
(D. Brian Paley)

I have seen this happening in some of my "test" 3 gal. bins, seeded with 25 mature worms.
I also agree with mendopete re. 1/2 lb/sq.ft.
The dia. of the 3 gal bin is 11" >> .66 sq.ft.
The max. pop. density I get in these are .5 lb. If I take out (harvest) the bottom half (finish compost) and put ALL the worms back with their ORIGINAL bedding, I could get it up to .7 to .8 lbs.
Please keep in mind, this is mass weight, NOT head count.

I seeded a couple with 50 mature worms and expected to have double the result in the same time period, but no chance.

RE: please help with "math"

Math and I really don't get along very well and are not on speaking terms, but when determining density, shouldn't you consider volume instead of area? Length x Width x Depth instead of just Length x Width? Cubic feet, not square feet.

RE: please help with "math"

I think, since composting worms are surface dwellers, hence the importance of area. Of course depth is important also but only up to a certain measure, I'd say around 12" to 16" because deeper than that it's normally where finished compost start. This depth apply to my bins of 3 sq.ft. & up.

RE: please help with "math"

While otis11's response is 'on', most people DON'T like math, and adding a third dimension complicates the math by at least a third.

When I first started raising worms - a whopping 5 months ago now - I too was surprised at all of the references to surface area instead of volume. I chalked it up to being just one of the idiosycrasies of the vermiculture community. All sorts of explanations for it can be given, the most common of which I would assume would follow otis11's. Personally, I believe that volume DOES matter. I believe that regardless of whether Eisenia fetida is essentially a "surface dweller" or not, if the depth of the substrate was "infinite" and there was severe crowding in the surface layer (0 to 12 inches, let's say), worms would distribute themselves throughout the substrate (not necessarily uniformly), to avoid their perception of crowding at the "surface".

"A pound per square foot" MAY actually be more relevant than "a pound per cubic foot".


RE: please help with "math"

Ideally, we all should want the wormies to gravitate to, and remain close to, the upper region of the bin. This is so because of density, and "humidity" (wetness) caused mainly by gravity.

Density prevention and aeration provide the more ideal environment for healthy, thriving worms.

The worms that remain at or near the surface areas are those that do the three things we want (feeding, pooping, reproducing) faster and more competitively than those morose, sickly, anti-social losers down in the ghetto going thru life's functions like the unhealthy, addled and stupefied ne'er-do-wells that they are.

All of that is the reasons to concentrate on surface area dimensions, surface feeding, and spot feeding.


Moderation, Patience, Diversity

RE: please help with "math"

Hey, my anti-social losers in the mucky ghetto of my catch bin are some of my best poopers and gettin-it-on-ers.

RE: please help with "math"

"Hey, my anti-social losers in the mucky ghetto of my catch bin are some of my best poopers and gettin-it-on-ers."

Imagine a "thumbs up" icon.


RE: please help with "math"

OK, I'm convinced. I'm gonna start saturating my bins with dangerous amounts of liquid....then water that down some more....bury all the food in the bottom so the worms can enjoy all that rotting, stinky stuff hopefully before the odor of it all becomes intolerable to humans... and before the worms drown.

But, all that can still be used. Just bury it in a raised bed in both a symbolic funeral and as a fertilizer source to that plot of soil.

Just to help me on one point: How does one evaluate the comparisons re health, reproductive qualities, and populations of top-feeding vermi living in the swamps at depth vs those thriving in the environs most worming enthusiasts have been duped into striving for all the years vermicomposting has existed.

Is it some sort of contrarian, revolution I somehow haven't happened upon? If so, please post some sources and sites so I can begin my conversions ASAP!
You know, just as verification.

Maybe some reputable stuff right here in the archives?

Oh!, and can find emoticons for the "thumbs up". Maybe not for the satirical ridicule and contempt it applauds.


Good luck, everybody. This thing with all the twitter-inspired type diatribe has lost much of its worthiness and has become not only a big waste of time but too much infused with stuff that leads wormers astray.

RE: please help with "math"

Astray from what?


RE: please help with "math"

RE: square foot vrs. cubic foot in stocking rates. In a large bin, worms stay on top where they are fed. In the "census" I referred to, the bed was about 30" deep. I only removed the top 8"active bed-run. There were few if any worms below.

Other type of bin management may be different. Some people vermicompost whole batches of food. Others stir or flip their bins over. But generally surface area is the determining factor.

I hope that makes sense.

Happy Wormin' and stay cool!

RE: please help with "math"

You seemed a bit grumpy in your last post. I wouldn’t recommend soaking down your bins.
My method is sort of inspired by your many small bins idea (and suits my “laziest man in the world, yet still fully functional” lifestyle.) I’ve got a couple small bins separating the feed/bedding bin from the base bin for air flow. Some of the worms like it better down there even though I don’t put food in them. Occasionally I will add some bedding if I think it’s getting too wet in the ghetto. I find it much easier to harvest from the muck. No food scraps or much bedding to separate. The castings aren’t that nice and fluffy, but when you make tea out of them, does that really matter?
At harvest time (during gardening months, once every few weeks) I’ll scoop out the muck, and put the worms into the high rent upper portions where bedding and food are abundant.
Without fail though, they still gravitate back down to the depths on their own. As far as surface dwelling, don’t wild versions of our worms generally occupy the top 10-18 inches of ground? My bin isn’t much taller than 3’ and not much more than a foot-and-a-half of substrate. So, even my bottom feeders are still technically surface dwellers.
Granted, as of the past few months, I’ve been trying to eat healthier and I never know what my son wants to eat or how much to eat, so both the dog and the worms have been eating a lot better. This might account for the added moisture that collects in the bottom.
I haven’t noticed any added smells coming from the bins.
This has been working for me for a little under a year. Last summer, I harvested from the top bin. I got a lot of compost (about 6 or 7 gallon buckets worth) but it took forever to separate.
But back to the original reason for my post: when I dig through my bin, it is chock full of worms from the bottom all the way to the top. Maybe I need to split the herd into another bin, but that is probably another issue. Anecdotally, it leads me to believe that to determine population density, volume, not just area needs to be considered.

RE: please help with "math"

Your bins are 1.8 Sq Ft. Yes, almost 2 Sq Ft, but not quite.
QUOTE: "my bins are 13.5 x 19.5 inches (area)"
13.5 X 19.5 = 263.25 Sq In.
Divide by 144 (12X12=144=Sq Ft)

RE: please help with "math"

"As far as surface dwelling, don’t wild versions of our worms generally occupy the top 10-18 inches of ground?"

NO! EF and other composting worms, unlike earthworms that come to the surface and drag foodstuff down into their deeper environs, composting worms nature...just under the surface of decomposing plant and other organic stuff lying on the surface.

Carlos Danger

RE: please help with "math"


Plastic Bins are certainly not "by nature". Furthermore, are you willing to wager large sums of money - seriously - that if I had a "large" bin, let's say 3 feet by 3 feet by 3 feet, and I put, oh say 90,000 Eisenia fetida in that "bin", that they would all REMAIN in the upper layer, at an AREAL density of 10,000 per SQUARE foot, as opposed to dispersing throughout the "bin"? Recall, that most people make the whole of the bin out of worm "food". Au natural, most of the E.f. food is, in fact, near the surface. Are you willing to state unequivocally - wager large sums of YOUR money - that if the whole substrate was food and the density at the "surface" was very high, that the E.f. would refuse to disperse throughout the substrate to avoid densities of 10,000 per square foot?

If so, I'll gladly take that wager.


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