Unacidulated mineral phosphatic materials and basic slag shall be guaranteed as to both total and available phosphate, and the degree of fineness as expressed in percentage passing through standard mesh sieves. In the case of bone, tankage, and other natural organic phosphate materials, only total phosphate must be guaranteed. If any fertilizer is sold, offered for sale, or exposed for sale in bulk, such plainly written statement herein required shall accompany each lot and parcel of such fertilizer.
§ 266.321, RSMo