(20) Assume the responsibility for successful revegetation, as required by subdivision (19) of this subsection, for a period of not less than five growing seasons, as defined by the secretary, after the last year of augmented seeding, fertilizing, irrigation or other work in order to assure compliance with subdivision (19) of this subsection: Provided, That when the secretary issues a written finding approving a long-term agricultural post-mining land use as a part of the mining and reclamation plan, the director may grant exception to the provisions of subdivision (19) of this subsection: Provided, however, That when the director approves an agricultural post-mining land use, the applicable five growing seasons of responsibility for revegetation begins on the date of initial planting for the agricultural post-mining land use; On lands eligible for remining assume the responsibility for successful revegetation, as required by subdivision (19) of this subsection, for a period of not less than two growing seasons, as defined by the director after the last year of augmented seeding, fertilizing, irrigation or other work in order to assure compliance with subdivision (19) of this subsection;