On or before January 1, 1994, the board shall evaluate rice straw for use as a solid waste landfill cover material or for use as an extender for currently used cover material. Rice straw or rice straw materials, when used as a substitute for or mixed with currently approved cover material, shall possess all the physical characteristics required in the definition of a cover material. The results of the evaluation shall be included in the report required pursuant to Section 40507.