A Mysterious Foam That Can Create Explosions on Midwestern Hog Farms

My friend and colleague Sean tipped me off to an article about a mysterious foam that grows in some hog farm manure pits, seen here in this remarkably disgusting photo. This foam traps methane gas, which can then explode. According to Brian Keirn, who wrote the report for Wired.com (here), six farms have exploded since 2009. The effects of the foam, which is a problem on one out of four hog farms in the midwest, are clear, but why some farms develop the foam and others do not is still unclear. One theory traces the foam to the increasing use of distillers' grain in the pigs' diets, although antibiotic use, changes in water use, and genetic modifications to pigs themselves are all on the table as possible contributors.