Have Cow, Will Compost

Good ole publisher's tact...they have sense enough to bury the icky bits deep in the bowels of an article. I was reading some fascinating stories on Terra Preta soil formation in the Amazon when I came across the bit where they used humanure to inoculate and condition the biochar used to create the soil. Yup, they mixed people poop and pee with charcoal to create some of the richest soil on the planet. And they grew their food on that. Ick.

But maybe I shouldn't cringe too much; after all, we do the same thing here. There are anti-dumping laws that limit how much sewage material you can dump into the oceans so our processed sewer sludge ends up being converted into a cheap fertilizer that's sold to farmers who grow our food. The marketing gurus wisely sensed that "processed sewer sludge" wouldn't sell well so they created the name, "Milorganite" for the sludge so it sounds more like a naturally mined mineral. Clever. I saw bags of milorganite for sale at Sunnyside Garden Sentres as a lawn fertilizer a few years back. Wasn't able to bring myself to buy it, even for the lawn.

Still, this whole humanure thing bears looking into. Other cultures in other parts of the world do recycle human waste into fertilizer for their fields. In fact, all of the long-term, successful, closed systems of agriculture included returning humanure to the soil. You had to keep the minerals and nutrients from leaving the land or the soil would become depleted over time. Since we're already eating food grown (imported or domestic) that's fertilized with humanure, I thought I would look into it further.

I remembered seeing a Home Depot flyer that advertised a composting toilet so I decided to find out how those worked. In the process, the Internet whimsically directed me to a link on how to compost a cow. I had to click on it. My curiosity demanded to know how they got the cow into the toilet.

Prior to the current regulations that say you have to take the carcass into an approved processing/rendering facility, people would simply compost their cow if it got hit by lightning. Now if you were able to get to it fresh, and you happened to have a backhoe, you could try the Hawaiian-luau-pig-in-a-pit thing, but alas, who the heck has a pit of coals at hand...especially in a lightning storm? Pity our lack of prescience or we would have more roast beef.

The thing to do to compost your dead cow is to bury it in a whole lot of sawdust. The high carbon:nitrogen ratio of the sawdust (500:1) helps to absorb the large amount of nitrogenous waste from the decomposing cow and a couple of years later, you have good compost. Humanure is composted in much the same way. You can make a simple composting toilet by doing your business in a large bucket and then covering it up with a layer of sawdust. When the bucket is full, you empty it into a humanure compost pile and let it break down. At some point some bright Amazonian must have realized that charcoal would help keep odours down in the pile and terra preta was inadvertently born. At least that's my theory.

I like to speed up my composting by adding weeds. They're high in nitrogen and minerals and break down very quickly. For those of you who worry about weed seeds, you can always try adding a cow. The existing composters are too small for that but we'll be building new ones soon....