S.D. Codified Laws § 47-21-56
Unless the bylaws prescribe the presence of a greater percentage or number of the members for a quorum, a quorum for the transaction of business at all meetings of the members of a cooperative having not more than one thousand members, shall be five percent of all members, present in person, and of a cooperative having more than one thousand members, shall be fifty members, present in person. If less than a quorum is present at any meeting, a majority of those present in person may adjourn the meeting from time to time without further notice. The sufficiency or requirement of a quorum for the transaction of business at a district meeting of members shall be established in the bylaws. However, the quorum may not be less than five members.
SDCL 47-21-56