(a) All registered voters in each county in a district shall elect two nonpartisan supervisors who shall hold office for a term of four years and until his or her successor is elected and qualified: Provided, That any county with a population of 100,000 based on the most recent decennial census shall elect one additional supervisor and any county with a population over 100,000 based on the most recent decennial census shall elect one additional supervisor for each 50,000 residents over 100,000.

(b) The provisions of § 3-1-1 et seq. of this code apply to the election of supervisors, and the terms of such members shall begin on July 1, next following the primary election at which they were elected: Provided, That if no candidate seeks the office, then the district shall advertise and select a candidate from the county in which the vacancy occurs and submit the name to the state committee for appointment.

(c) A candidate for supervisor must have experience in agriculture, as that term is defined in § 19-21A-3 of this code; conservation; or natural resources.

(d) Any vacancy occurring in the office of supervisor shall be filled by the state committee by appointment of a person from the county in which the vacancy occurs. Within 90 days after the vacancy occurs, the district shall advertise and select a candidate from the county in which the vacancy occurs and submit the name to the state committee for appointment. If the unexpired term is for less than two years and six months, the appointed person holds office until the expiration of the term. If the unexpired term is for more than two years and six months, the appointed person holds the office until a successor is elected in the next primary or general election and qualified.