Worm Composting with Dog Poo

Worm Composting...

“I found the newsletter on manure very informative.  I do have a question concerning manure for worms.  I do not have much access to “regular” animal farm manure, however, I do have an abundance of dog poo. Has anyone ever used dog dirt as a food source for their worm bins?

 If so, are there any pre-composting requirement or health concerns?  I am so glad that I found this newsletter because it covers topics that are on my mind! Thanks,” ~ Rick

Hi Rick!

This an excellent question and something that seems to come up quite a bit – understandably, given the number of dog owners out there!

Dog, cat and even human ‘manures’ are all rich in nitrogen and in principle could work very well in the worm composting system if properly managed. That being said, they should all be used with a considerable amount of caution since they can represent a potential health hazard.

My recommendation for those interested in vermicomposting with dog and cat wastes is always the same – start up a completely separate system, preferably one located outside. Apart from the potential health issues (we’ll discuss in a minute), these materials just aren’t all that pleasant to deal with.

While farmyard manure can certainly have a potent smell, it is much more tolerable than the smell of large quantities of dog or cat poop. Plus, who wants to accidentally stick their hands in this stuff when digging around in their worm bin? Not me – that’s for sure! 🙂

As far as health concerns go, cat, dog and human wastes contain fecal coliform bacteria among other potentially nasty pathogens.

Cat waste in particular warrants extra caution, since it can also contain a parasitic protozoan called Toxoplasma gondii. This organism is relatively harmless for many people who become infected, but it can be a serious threat for pregnant woman (since it can harm the unborn child) or those with compromised immune systems.

Just so you know, most cases of Toxoplasmosis actually result from the consumption of raw meat, NOT from contact with cat feces (http://www.metrokc.gov/HEALTH/prevcont/toxoplas.htm), so don’t let this terrify you too much, unless of course you like your steaks rare! haha

Setting up an outdoor pet waste composting system is very easy, but there are some guidelines you should keep in mind. For starters, make sure to locate the system(s) a good distance away from the nearest water body. It’s not a bad idea to locate it away from your vegetable garden (assuming you have one) and other compost bins as well.

I would suggest digging a good sized hole in the ground, perhaps 3 feet deep and 2-3 feet across. Line the bottom of the hole with a thick layer of shredded cardboard, peat moss, or fall leaves.

Then you simply start adding your pet waste as it becomes available. Each time you make a deposit be sure to add some more bedding material as well and perhaps a sprinkle of water as well.

Covering the pit with a standard black plastic backyard composter would work very well since it would allow you to add a lot more material, and would also protect the contents from rain – it is definitely better if you are in control of the amount of water added.

By the way, I know you were asking specifically about dog waste, but for the benefit of those thinking about using cat waste – definitely do NOT add the entire contents of your litter box (unless you use a natural litter material like “Yesterday’s News” or “Swheat Scoop”).

When I was young and foolish I tried dumping the entire contents of a littler box in an outdoor worm system and just ended up with a big mess of clay.

If you plan to add composting worms I would suggest either A) Adding the entire contents of a worm bin over top of the bedding in the bottom of the hole, then adding another layer of bedding before starting to add pet wastes, or B) simply filling  up the hole with pet waste and bedding as described, then letting it sit for a couple weeks before adding the worms.

Fresh pet waste will give off a lot of ammonia gas, and just generally won’t be all that inviting to your worms, but once it has been mixed with the bedding material and allowed to age for a bit they should readily consume it. Once they become established in the system, adding fresh wastes to the top won’t be an issue at all (since they will continue consuming older materials down below).

While I probably wouldn’t ever actually remove compost from one of these systems, it might not be a bad idea to locate your pet waste bins near some trees or other ornamental plants that can benefit from the nutrients.

One other option for these sorts of wastes (and the reason I mentioned human wastes) is of course the ‘Composting Toilet’. I’ve heard of people having thriving populations of red wigglers inside these systems, and you can certainly dump your pet wastes in them as well.

Hope this helps!

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