S.D. Codified Laws § 11-2-28
The plan, ordinances, restrictions, and boundaries adopted pursuant to this chapter may be amended, supplemented, changed, modified, or repealed by action of the board. Any such modification or repeal shall be proposed in a resolution or ordinance, as appropriate, presented to the board for adoption in the same manner and upon the same notice as required for the adoption of the original resolution or ordinance. The amendment, supplement, change, modification, or repeal may be requested through a petition by twenty percent of the landowners in the zoning district or districts requesting change. For purposes of this section, the term, landowner, means any person who owns land in the county as evidenced by records in the offices of the register of deeds and clerk of courts. If land is sold under a contract for deed that is of record in the office of the register of deeds in the county, both the landowner and the individual purchaser of the land, as named in the contract, are treated as landowners. Any charitable, benevolent, or religious society that owns any agricultural land in the county is not a landowner for purposes of this section if the agricultural land is exempt from taxation pursuant to § 10-4-10, but any such society is a landowner for purposes of this section for any of its real property in the county that is not exempt from taxation pursuant to § 10-4-10.
SDCL 11-2-28