43 U.S.C. § 316f

(a) Period of lease A lease may be made for such term as the Secretary deems reasonable, but not to exceed fifty-five years, taking into consideration all factors that are relevant to the exercise of the grazing privileges conferred. (b) Size of leasehold Leases shall be made for grazing on a definite area except where local conditions or the administration of grazing privileges makes more practicable a lease based on the number of stock to be grazed. (c) Terms for surrender of lease Each lease shall provide that the lessee may surrender his lease, and, if he has complied with the terms and conditions of the lease to the time of surrender, may avoid further liability for fees thereunder by giving written notice to the Secretary of such surrender. The lease shall specify the length of time of notice, which shall not exceed one year. (d) Terms for renewal of lease Each lease shall provide that the lessee may negotiate for renewal of such lease, subject to the provisions of this subchapter, at any time during the final five years of the term of such lease.