The board shall apportion the cost of an assessment according to the special benefits accruing to the real property or product because of the project or service to be financed by the assessment. The cost may be assessed on real property or on an agricultural product produced on real property, as appropriate:
(1) equally by front foot or by square foot of the land area of the real property;
(2) equally by acreage of the real property;
(3) according to the value of the real property or agricultural product as determined by the board, which may consider the value of a structure or improvement on real property;
(4) based upon the productivity of land subject to the assessment or on which the agricultural product subject to the assessment is produced;
(5) in proportion to the value of the agricultural product produced on the real property for the year preceding the year of the assessment; or
(6) according to any other reasonable assessment plan that imposes a fair share of the cost on property or agricultural products similarly benefited.