Mysterious, exploding poop substance killing Minnesota pigs

Mystery foam rises out of a pig poop pit.
Mystery foam rises out of a pig poop pit.

Hog farmers and scientists are baffled by an unidentified foamy substance bubbling out of manure pits at hog farms in Minnesota and surrounding states.

The methane-filled foam, which can rise four feet above ground level, has been responsible for a half-dozen barn explosions during the past three years.

Thing is, farmers had never encountered the poop foam until about five years ago. What it is, and why it forms, remains a mystery -- one that University of Minnesota researchers hope to crack soon.

Chuck Clanton, a bioproducts and biosystems engineering professor, told the Minnesota Daily that researchers right now are trying to figure out how different microorganisms -- primarily bacteria -- develop in the manure pit. They suspect a new set of species has formed in these pits in the last few years, in part as a result of ethanol-byproduct grains that have recently been incorporated into hogs' diet in higher volumes.

Still, there's clearly more to the story than just a dietary change -- as Clanton explains,

Another shot of the foam.
Another shot of the foam.

The pits are emptied each fall, after which waste builds up again, turning them into something like giant stomachs: dark, oxygen-starved percolators in which bacteria and single-celled organisms metabolize the muck.

Methane is a natural byproduct, and is typically dispersed by fans before it reaches explosive levels. But inside the foam's bubbles, methane reaches levels of 60 to 70 percent, or more than four times what's considered dangerous. The foam can reach depths of more than four feet.

Disturb the bubbles, and enormous quantities of methane are released in a very short time. Add a spark -- from, say, a bit of routine metal repair, as happened in a September 2011 accident that killed 1,500 hogs and injured a worker -- and the barn will blow.

There's potentially a lot of money riding on the U of M's effort to figure out the foam -- the Daily reports that considering the cost of materials and hogs, a barn explosion costs a farmer up to $300,000.

We're no hog farmers, but pigs are pretty smart, right? Maybe they could be potty-trained?

-- Hat-tip to A.V. Club Twin Cities for the headline.

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