The Secretary of Agriculture, with respect to forest land under his jurisdiction, and the Secretary of the Interior, with respect to forest land under his jurisdiction, are severally authorized, for the purposes specified in section 583 of this title, to enter into cooperative agreements with private owners of forest land within a cooperative sustained-yield unit, established pursuant to said section, providing for the coordinated management of such private forest land and of federally owned or administered forest lands within the sustained-yield unit involved. Each cooperative agreement may give the cooperating private landowner the privilege of purchasing without competitive bidding at prices not less than their appraised value, subject to periodic readjustments of stumpage rates and to such other conditions and requirements as the Secretary may prescribe, timber and other forest products from federally owned or administered forest land within the unit, in accordance with the provisions of sustained-yield management plans formulated or approved by the Secretary for the unit; shall limit the time, rate, and method of cutting or otherwise harvesting timber and other forest products from the land of the cooperating private landowner, due consideration being given to the character and condition of the timber, to the relation of the proposed cutting to the sustained-yield plan for the unit, and to the productive capacity of the land; shall prescribe the terms and conditions, but not the price, upon which the cooperating private landowner may sell to any person timber and other forest products from his land, compliance by the purchaser with such conditions to be required by the contract of sale; shall contain such provisions as the Secretary deems necessary to protect the reasonable interest of other owners of forest land within the unit; and shall contain such other provisions as the Secretary believes necessary to carry out the pur