Any agreement evidencing a lien on crops required by § 43-27 to be docketed in a clerk’s office may be destroyed by such clerk after twenty-four months from the date the same is docketed in his office. Any “Crop Lien Book,” together with the index thereto, required by § 43-27 to be kept in a clerk’s office, may be destroyed by such clerk after twenty-four months from the date the last entry has been made therein, provided the same is replaced with a similar book and index for the recordation of current liens.