SD Statute 10-6-31
Criteria for classification of land as agricultural. For tax purposes, land is agricultural land if it meets two of the following three criteria:
(1) At least thirty-three and one-third percent of the total family gross income of the owner is derived from the pursuit of agriculture ... or it is a state-owned public shooting area or a state-owned game production area as identified in § 41-4-8 and it is owned and managed by the Department of Game, Fish and Parks;
(2) Its principal use is devoted to the raising and harvesting of crops or timber or fruit trees, the rearing, feeding, and management of farm livestock, poultry, fish, or nursery stock, the production of bees and apiary products, or horticulture...
(3) It consists of not less than twenty acres of unplatted land or is a part of a contiguous ownership of not less than eighty acres of unplatted land....
The deadline to file for an agricultural classification is May 1st.