Before any buildings, wells, irrigation improvements, dams, or drainage ditches are placed upon school lands by a lessee, written approval must be obtained from the Board of Educational Lands and Funds, except necessary improvements for the temporary handling and sheltering of livestock, and such improvements where approval is secured shall be called permitted improvements and belong to the lessee and the lessee has the right to be paid a sum of money equal to the value which the improvements add to the value of the land by the buyer of the land or the new lessee in accordance with procedures as given in sections 72-240.10 to 72-240.23 and 72-258. The value to the land of each permitted improvement shall not exceed its replacement cost less depreciation. Any such improvements placed upon school lands before September 14, 1953, and any improvements which were bought by new lessees during an involvement by the state in the transferring of leases after September 14, 1953, shall be considered as authorized or permitted improvements whether or not approval has been secured from the board and shall belong to the lessee unless there has been a provision in the lease to the contrary or unless there has been some written agreement between the lessee and the board to the contrary. Any improvements placed upon school lands after September 14, 1953, where written approval for such improvements was not obtained from the board and where there was no involvement by the state in the transferring of leases or other written agreement with such lessees to the contrary, shall be called nonpermitted improvements and considered as owned by the lessee, whether or not the nonpermitted improvements are attached to the land, unless there has been a provision in the lease to the contrary, and, the lessee shall have the right either (1) to remove such improvements from the land any time during the term of the lease or within six months after the land is sold or leased to a new lessee, and when the nonpermitted improvements are removed the old lessee shall clean up the debris caused thereby or bury it at least three feet below the surface of the land and any basements or holes caused by the nonpermitted improvements shall be filled such that cultivated crops can be grown on the land or (2) to sell the nonpermitted improvements to the buyer of the land or the new lessee at prices agreed upon by the old lessee and the buyer or new lessee. If the parties cannot agree upon the prices of the nonpermitted improvements, or if the improvements are not removed from the land within six months after the land is sold or leased to a new lessee other than the old lessee, the improvements shall become the property of the state. The board shall notify the old lessee by certified letter of the name and address of the purchaser of the land or the new lessee within ten days after the land has been sold or leased to a party other than the old lessee. The board shall, at the same time, notify the old lessee how much money the old lessee shall have to place in escrow with the county treasurer of the county in which the land is located for each nonpermitted improvement if the old lessee takes the option to remove any or all nonpermitted improvements to guarantee removal of debris and to do other things required by the board so as not to damage the land. The old lessee shall within thirty days after receipt of such certified letter notify the board which improvements he or she intends to remove from the land and which shall be left on the land and show proof of deposit of escrow money. If the debris is not removed and if other things required by the board are not done within the six-month period after the land is sold or leased, the old lessee shall forfeit the money placed in escrow to the state, and the board shall hire a contractor to do the things required of the old lessee in order that there not be damage to the land. Any money left in the escrow fund after being depleted by making payment to the contractor for the work done shall be remitted to the old lessee. The board shall have authority to sell any improvement left on the land.