(1) Commencing July 1, 1990, the board may levy on growers of wheat an excise tax of not to exceed one and one-half cents per bushel upon all wheat sold through commercial channels in the State of Nebraska. Commencing on October 1, 2012, there is hereby levied an excise tax of four-tenths percent of the net market value of wheat sold through commercial channels in the State of Nebraska. The first purchaser of such wheat shall levy, impose, and collect the tax at the time of settlement for the wheat. Under the Nebraska Wheat Resources Act, no wheat is subject to the tax more than once.

(2) After October 1, 2014, the board may, whenever it determines that the excise tax levied by this section is yielding more or less than is required to carry out the intent and purposes of the Nebraska Wheat Resources Act, reduce or increase such levy for such period as it deems justifiable, but not less than one year, and such levy shall not exceed five-tenths percent of the net market value. Any adjustment to the levy shall be by rule and regulation adopted and promulgated by the board in accordance with the Administrative Procedure Act.