S.D. Codified Laws § 10-6-112
For tax purposes, land is agricultural land if the land's 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, all for intended profit. Agricultural land also includes woodland, wasteland, and pasture land, but only if the land is held and operated in conjunction with agricultural land and is under the same ownership. For purposes of this section, the term, principal use, means the primary use to which the land is devoted. This definition is intended to reference the primary and predominant use of the land as opposed to a mere secondary and incidental use.
In addition, to be classified as agricultural land for tax purposes, the land must meet one of the following criteria:
The owner shall produce to the director of equalization any writing that is requested by the director for the purpose of verifying that the requirement of this subdivision has been satisfied; or
For the purposes of this section, the term, management unit, means any two or more parcels of land, whether adjoining or not, under common ownership located within this state and managed and operated as a unit for one or more of the principal uses listed in this section. No parcel of land within a management unit may be more than twenty air miles from the nearest other parcel within the management unit. If requested by the director, the owner shall provide supporting documentation of the land contained in the management unit.
SDCL 10-6-112