Each director shall be elected for a term of six years from and after the date of election and, unless removed from office as provided in Section 73-14-59 N.M. Stat. Ann., shall serve until a successor is duly elected and has qualified; provided that at the first election, one director shall be elected for a term of two years, two for a term of four years and two for a term of six years, to be determined according to counties if there is land in any district in more than one county, by the board calling the election. Appointments to fill vacancies shall be for the unexpired term of the director whose office becomes vacant.