Adverse possession rule is 15 years. Vermont law provides that a person who possesses another’s property (or who uses a right of way over someone else’s property) obtains title to that property (or a legal right over that property) if their possession was “open, notorious, hostile and continuous for the full statutory period of fifteen years.” 12 V.S.A. § 501. Lawrence v. Pelletier, 154 Vt. 29 (1990). If the landowner has permitted the person to use the property no adverse possession claim can be made unless there is an express or implied revocation of that permission.
Note that it takes a court action to transfer title by operation of this law. Only when the town clerk is given such an order for recording as a deed to the property can the grand list be changed to reflect the new ownership.
A good recommendation for lands maintained or used by another is to have a signed lease agreement by both parties (even if it is for 10 years and just $1) for the field or R.O.W. This is an example of an agreement about both parties understanding the ownership of the property.