At the expiration of any lease issued for grazing purposes only, the commissioner of public lands in his discretion and after investigation of facts may withhold approval of application to lease any land filed by a previous lessee, which land is located within the duly permitted individual Taylor grazing allotment of another where the land is not being used by prior lessee; provided, however, the holder of such grazing allotment has made timely and proper application to lease such land.