The term of office of all members of the commission, except ex officio members, shall be two years from the date of their election and until their successors are qualified. However, of the first members of the commission, one-half of the producers shall serve for one year, and one-half of the producers shall serve for two years, with the determination of the term of each such member made by lot at the time of the election. Terms of office of each member of the commission shall be limited to four consecutive terms. A member of the commission who was selected by lot to serve a one-year term may serve four consecutive terms in addition to the first one-year term.