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.
Hill is among the many Midwestern pork producers who use deep pits under their barns to accumulate manure throughout the year. In the fall, after fields are harvested, the nutrient-rich slurry gets pumped out of the pits and injected into the cropland.