In any county wherein an election has heretofore been held or shall hereafter be held pursuant to the provisions of Kan. Stat. Ann. § 19-2113, or any amendments thereto, at which election a proposition to sell the county farm or any part thereof has been approved or shall hereafter be approved by a majority of the votes cast, the board of county commissioners, in its discretion, may reserve to the county all or any part of the minerals or mineral rights in and under said county farm or any part thereof for a period of not more than fifteen (15) years and as long thereafter as oil or gas is produced in paying quantities therefrom when it sells said county farm or any part thereof.