Every warehouseman shall annually, during the first week in July, publish by posting in a conspicuous place in the public warehouse of the warehouseman, a schedule of grain storage and handling rates for the ensuing year. The schedule shall be kept posted in a conspicuous place in the public warehouse. The rates shall not be changed during such year. No discrimination in rates shall be made by any warehouseman. [Amended by 1955 c.731 § 10]