A subsequent lessee or a purchaser of the land shall pay the prior lessee the reasonable value of improvements erected by him within permission of the board of county commissioners, that are not physically capable of removal, and such payment shall be made before a lease, contract of purchase, or deed is issued to such subsequent lessee or purchaser. The value of the improvements shall be determined as of the date of such lease, contract of purchase, or deed.
SDCL 7-31-9