Boulder Vermicomposting

How many worms do you have?

June 1st, 2009

I was asked by a friend for some worms.  I have previously handed out vermicompost with worms in it to friends for free.  I was considering trying to sell worms, but really had no idea how many I had.

To figure this, out, I filled a tray with vermicompost.  Then I manually separated the worms from the compost, using sunlight and time.  I ended up with a ball of squirmy worms.

I estimated the weight of the worms at 1.5 oz.  Then I measured the cubic volume of vermicompost I had separated, which ended up being 120 cubic inches.  This means that there was one ounce of worms for every 80 cubic inches.

I then measured the height and width of my worm bin.  It is 24 inches by 24 inches.  I then estimated how far I’d seen worms down in the bin.  Redworms typically stay in the first meter (approximately 36 inches) of soil, but I had recently dug out some castings from the bottom and hadn’t seen any worms there.  So I estimated the worms were in the upper 16 inches of the bin.  Multiplying these together gave a volume of 9,216 cubic inches.

Dividing the number of populated cubic inches in the entire worm bin by 80 gave me the number of ounces of worms in the bin, and dividing that by 16 indicated that there were approximately 7 pounds of worms in my bin.  Given I started with one pound two years ago, that is quite a return on investment (especially given that all the materials I’ve added to the bin were free).

Caveats: if I were serious about this, I would pull and harvest multiple samples, as that is the key calculation.  The above assumes that worms were distributed throughout the bin in the same manner as they were in the sample.

But, hey, it was fun to figure out–I was surprised!

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