Okla. Stat. tit. 2, § 2-8-77.18: Exchanges

Nothing in the Oklahoma Fertilizer Act shall be construed to

restrict or avoid sales or exchanges of fertilizer to each other by

importers, manufacturers, or manipulators who mix fertilizer

materials for sale, or as preventing the free and unrestricted

shipments of fertilizer to manufacturers or manipulators who have

registered and licensed their brands as required by law.