Montana Title 70. Property § 70-19-408. Claim founded on instrument or judgment--what considered possession and occupation

(1) For the purpose of constituting an adverse possession by any person claiming a title founded upon a written instrument or a judgment or decree, land is deemed to have been possessed and occupied in the following cases:

(2) Where a known farm or a single lot has been partly improved, the portion of such farm or lot that has been left not cleared or not enclosed, according to the usual course and custom of the adjoining country, shall be deemed to have been occupied for the same length of time as the part improved and cultivated.