It’s about that time of year when hog farmers begin the annual process of pumping a year’s worth of manure out of the pits under their barns. The nutrient-rich slurry will fertilize cropland. But there’s an ongoing problem in these pits: a mysterious foam that sometimes forms on the manure. As Harvest Public Media’s Amy Mayer explains, no one quite understands why gases get trapped in the pits, but the foam has been causing explosions. That’s right; this is a story about exploding manure pits.
Howard Hill pulls his red Chevy pick-up truck up to a barn near Union, Iowa, that houses 1,000 of his hogs. In the truck’s bed is a 55-pound bag of Rumensin 90, a common antibacterial ingredient in cattle feed that helps reduce bloating. Pigs don’t eat it. Hill brought it here to dump into the manure pit under the hogs.