Depending on where you are traveling from to get you your ground in Ottumwa, but there are co-ops in Knoxville, Pella, Chariton, Albia (Smith's Fert. & Grain), Albia (Quality Ag), and I'm pretty sure there is a co-op in Troy and a Golden Furrow (fert./chem. retailer) in Eldon.
A 50# bag...