Vermicomposting Cat Litter?

Question from Ken:

Hello-live in a semi-rural location in Oregon. Have the cat wastes, with biodegradable litter, in an outdoor wooden sided bin. Would like to try worms.
What should we do to make the bin more attractive to worms? If we purchase worms, do I just dump the worms on top of the pile?
Thank you,

Hey Ken,
I’ve worked a fair bit with biodegradable cat litters, and can confirm that vermicomposting these wastes is indeed possible. But there are definitely some nuances (to put it mildly). The big challenge is almost always going to be ammonia release. Worms are extremely sensitive to this gas (it kills them at very low levels), and as I’m sure you know, the amounts wafting off of used cat litter can be enough make your nose hurt and eyes water.

SO…it is going to be important for there to be a pretty decent aging/composting period before worms get involved (i.e. absolutely don’t add them straight to the system). It sounds like you have actually been depositing the wastes in your bin for a period of time – so perhaps there are indeed zones further down where the worms would be ok.

Regardless, my advice would be to start by setting up another system very close to the litter system. This way the worms have a totally safe habitat to hang out in until the litter system is worm-friendly (assuming it isn’t already).

One of the systems I set up (a few years back) was a typical backyard composter where compostable cat litter/waste + bedding (cardboard etc) was deposited over time. What’s funny is that my plan had been to let it age for quite a long time before attempting to add the worms – but as it turned out, local Red Worms (from other systems in my yard) ended up finding it on their own and established themselves a lot more quickly than I thought would be possible!

Bottom-line, ya never know! But the key is to avoid taking any chances. Make sure they have a safe habitat somewhere close by, and you’ll likely start finding them in the litter system before long.

Hope this helps!

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    • Andrew
    • May 17, 2018

    I currently compost my dogs waste, and I have a suggestion for the cat waste as well.

    Currently I have 2 buckets setup, and I bokashi the poop. This process basically ferments the waste, and impregnates them with effective micro organisms. Once the bucket fills up, I let it sit closed off for 2 weeks to ferment completely. Once done, I bury the waste in my yard by digging a hole, dumping the bucket, mixing its contents with a little soil, and in a few weeks the waste is mostly turned into compost.

    I have used bokashi waste(not poop, but kitchen scraps) in worm bins in the past, and they were eaten up fairly fast, so I would assume this pre-composting process for cat poop would be just as effective. I do plan on starting an outdoor bin for the dog waste in the near future to test.

    I wouldn’t suggest using this compost in vegetable garden although supposedly the process of bokashi does kill off parasites, and harmful bacteria. But I would still advise against it unless you took a sample of the finish product in for testing.

    To get started on this method you can either purchase bokashi bran, or purchase EM-1 and make your own bran/paper material. OR you can make your own EM solution. All this information is available online and high highly suggest it for pet waste.

    • Bentley
    • May 17, 2018

    Hey Andrew
    Really interesting idea! I remember being impressed with the lack of foul smell when I tried bokashi for kitchen scraps (including meat etc). Would be interesting to see how it works for pet wastes. I’ve been meaning to test out bokashi again – so perhaps this would be a good “excuse” to do so (now that I am collecting compostable cat wastes again).

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