The permitted improvements and growing crops covered by sections 72-240.10 to 72-240.23 and 72-258 shall be deemed to be separate permitted improvements and if the board and the lessee agree as to the value of some permitted improvements but disagree as to the value of others, only those on which they do not agree need be appraised under the appraisal provisions of sections 72-240.10 to 72-240.23 and 72-258.