Batch composting
>> Saturday, January 16, 2010
Today I started a couple of batch vermicompost bins with some excess waste I had building up and because I thought that the worm populations in some other bins were getting high, and overcrowding doesn't encourage breeding.
So far on this site I have described the process of continuous vermicomposting- a worm bin is set up and waste material for composting is added gradually, as it becomes available. Continous vermicomposting can be either closed where you keep adding material until the bin fills, or flow-through.
With a closed system, when it is full, the compost, worms and undigested material are separated in a process known as 'harvesting', and the process is then re-started.
In flow-though system, harvesting and feeding are continuous. Feedstuff is added at one end, and compost removed at the other.
Batch composting, on the other hand, is when all the materials, bedding and waste are placed in a container with worms and left until the material is all converted to compost. Nothing new is added during this process except water, if needed. The container can be as small as a plastic box or as large as you need. In India for example, vast pits are dug in the ground, worms in some sort of safe bedding are placed at the bottom and pre-composted agricultural waste is added on top. The pit is covered to protect from sun and to reduce evaporation, and the only care it gets until harvesting is a check on moisture levels.
My batch bins were started with some aged horse manure followed by worm-rich partially-decomposed waste from three other bins (including the overfed can-o-worms) that I felt looked as if they were getting crowded), and some 'new' kitchen waste that had started decomposing nicely (it was warm to the touch). I added some shredded cardboard to the new kitchen waste to balance carbon nitrogen rations and to improve aeration. The three additions are kept separate- the manure is a safe layer for the worms to retreat to if the decomposition process gets nasty.
I won't be adding anything more to these bins, just checking on them about once a week to make sure they're not drying out or the food isn't running out.
4 comments:
Hi Catherine - great to have a fellow Irish worm composter. James
Glad you enjoyed the post!
Hi, Catherine.
I did this with a small in-ground trench that's similar to your India example. I dug up the worms about 2 months later and used them to populate other bins. How long will it take your batch bins to fully ripen? Roughly what weight of worms in how much bedding/food are these bins started with? Last question for tonight...how do you determine that a worm bin is overcrowded and ready for a spinoff?
Thanks,
Andrew in Berkeley
I won't try to predict how long the bins will take to ripen because it depends alot on the temperatures round here, and anyway, I won't let them fully finish off. If I wait until there's no food at all, the adult worms will shrink, and the babies stop hatching.
I don't know how many worms are in each bin because to weigh them I'd have to harvest and I'm too lazy. I also prefer to transfer the worms with minimum diruption.
As for when a bin is ready for division- that's a bit of guesswork. It 'looks' ready. From experience I know that at that concentration of worms there will be less cocoons being laid, whereas as soon as I divide- the worms start breeding like mad.
If you're thinking of dividing a bin, or takign some worms out of it- if there's worms in every handful and you don't have to go looking for them, then it will do your bin no harm. The ones left behind will replace the missing ones in no time at all.
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