Each licensed distributor of commercial fertilizer shall file with the secretary of agriculture and natural resources on forms furnished by the secretary an annual statement for the period ending December thirty-first setting forth the number of net tons of each grade of commercial fertilizer distributed in this state during the reporting period. The report is due on or before the thirty-first of January following the close of the reporting period and on the basis of the statement each licensed distributor of commercial fertilizer shall pay the inspection fee at the rate pursuant to §