All parcels of land becoming the absolute property of the state under the provisions of the 1938 Supplement to Mason's Minnesota Statutes of 1927, section 2139-2, and acts amendatory thereof or supplementary thereto, situated within any conservation or reforestation area created under the provisions of sections 84A.20 to 84A.30, or 84A.31 to 84A.42, shall be classified by the county board of the county wherein such parcels lie as agricultural and nonagricultural, which classification shall be approved by the commissioner of natural resources before any lands are offered for sale. The county board of the county wherein such parcels lie shall determine the appraised value of all lands classified and approved as agricultural and may reappraise annually if in their judgment it be deemed necessary to carry out the intent of sections 282.14 to 282.22. Any merchantable timber on such agricultural land shall be appraised separately, and such appraisal approved by the commissioner of natural resources. All such parcels of land, classified as agricultural, shall be sold by the state at public sale, as provided in sections 282.15 and 282.16, when it shall be determined by the county board of the county wherein such parcels lie that it is advisable to do so. No such lands shall be sold by the board of county commissioners without the approval of the commissioner of natural resources. All sales of land shall be made in accordance with the subdivisions thereof by the United States surveys unless the same shall have been subdivided into smaller parcels or lots, but no land shall be sold in larger quantity than 160 acres.