S.D. Codified Laws § 49-34-12
Any trust deed or mortgage described in § 49-34-9 may be assigned or discharged by filing for record in the office of the secretary of state and in the office of the register of deeds of each county, if any, in which the trust deed or mortgage shall have been filed for record an instrument of assignment or discharge executed in the manner and setting forth the information required with respect to real estate mortgages by §§ 44-8-13 and 44-8-14, respectively; provided, however, that no such instrument need set forth the description of the mortgaged property, except that an instrument of discharge whereby less than all the mortgaged property is released from the lien of the trust deed or mortgage shall set forth the full description of, or clearly identify by reference to numbered or lettered portions of the descriptions as the same appear in the trust deed or mortgage, the property so released.
SDCL 49-34-12