All agricultural products stored for the producer in their raw or natural state, and cotton in any form stored for the producer, in storage in a warehouse under this article or deposited temporarily in such a warehouse pending storage shall be kept insured at full market value by the warehouseman against loss or damage by fire, lightning, and extended coverage, except that cotton shall be insured against loss or damage by fire and lightning only. Such insurance shall be carried in an insurance company or companies of the warehouseman's choice authorized to do business in this state, and evidence of such insurance coverage in form to be approved by the Commissioner of Insurance shall be filed with the Commissioner of Agriculture. Such insurance shall be provided by, and carried in the name of, the warehouseman; provided, however, that a producer depositing or storing agricultural products who does not wish to have his products insured by the warehouseman may relieve the warehouseman of that duty by notifying the warehouseman in writing that he does not wish his agricultural products insured.