Pet Waste Composting

If you’ve read a fair bit about backyard composting you will likely know by now that one of the cardinal rules is “don’t add pet waste to your compost bin”. This advice certainly has merit, at least as far as a regular compost bin goes (i.e. one you add your kitchen waste to, and eventually empty for the garden). After all, these materials can contain various pathogens, and aren’t exactly all that enjoyable to work with.

I should mention that the term “pet waste” is actually far too broad to be used in this context. There are many different types of pets out there, and a lot of them produce waste materials that make for an excellent addition to your compost piles. Really, any of the herbivorous rodents (is there such a thing as a carnivorous rodent - haha?) - such as rabbits, gerbils, hamsters, guinea pigs - will create some quality compost fodder for you. It will be very easy to work with (not wet and smelly) and there won’t be the same risks involved.

I think the ‘no pet waste’ rule is definitely more applicable to carnivorous (or at least omnivorous) animals. Of course, the two most popular pet poop produces that fall into this category would be cats and dogs. Both of these animals produce wastes that are not only unpleasant to work with in general, but they can also contain nasty microbes as well.

Cat waste in particular warrants extra caution, since it can 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 (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 (see http://www.metrokc.gov/HEALTH/prevcont/toxoplas.htm), so there’s no need to get ultra-paranoid about it - unless of course you like your steaks rare!

While I definitely DON’T recommend adding dog and cat waste to your ‘regular’ bins, I do in fact recommend setting up a completely separate system to handle these wastes - after all, why bag it up and send it off to the landfill when you can easily process it yourself and take advantage of the extra source of plant nutrients as well.

A pet waste composter should be set up a good distance away from your other composting systems and vegetable gardens, and as far as possible from the nearest water body (at least a good 100 yards or more). You can start by simply digging a hole in the ground - perhaps 2-3 feet deep and 2 feet across. Once the hole is dug you should add a nice thick layer of shredded cardboard, or some other carbon-rich, absorbent material (coir, shredded paper, aged straw etc) in the bottom. I would also recommend using some sort of enclosure over top. A regular plastic backyard composter will work fine. Aside from leaving you in control of the amount of water added (the last thing you want is to let it get flooded), this will also allow you add a lot more material, and should even help to ward off any curious children/animals.

Now all you have to do is start adding your poop (well, not YOUR poop - although I suppose you could - haha!), along with more bedding material and a sprinkle of water with each deposit. If you leave one of these systems to sit for a couple weeks or so without adding any more fresh waste (you might want to start up a second system), you could also add some composting worms. The worms would help you turn the material into compost much more quickly than would occur by simply letting it sit - but the worms definitely need a buffer zone from the fresh waste materials (hence the suggestion to let the system age for a bit) since it is a little too potent (with ammonia etc) for their tastes.

I wouldn’t personally harvest the compost from these composters - I would more likely try to put them in a strategic location so that surrounding trees/shrubs could take advantage of the rich compost being produced.

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Written by Compost Guy on May 7th, 2008 with 10 comments.
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