SDCL § 15-3-13: Acts constituting adverse possession under claim other than written instrument or judgment.

For the purpose of constituting an adverse possession by a person claiming title not founded upon a written instrument, or judgment, or decree, land shall be deemed to have been possessed and occupied in the following cases only:

(1) Where it has been protected by a substantial inclosure; or

(2) Where it has been usually cultivated or improved.