N.M. Stat. § 19-7-45
This act [19-7-37 to 19-7-45 NMSA 1978] shall not be construed to affect any assignment, mortgage or other instrument covering any purchase contract or lease of state lands for grazing or agricultural purposes or improvements thereon heretofore given for the purpose of securing any indebtedness and any such instrument or a certified copy thereof may be filed in the office of the commissioner of public lands and when so filed shall be constructive notice to all persons of the contents thereof and the lien created thereby may be foreclosed in accordance with the provisions of this act. Provided, however, the provisions of this act prescribing forms or requiring the approval of assignments by the commissioner of public lands shall not apply to such instruments.
NMS § 19-7-45