Notwithstanding any other provision of law, the Secretary, if he determines that it will not impair the effective operation of the program involved, (1) may permit the owner and operator of any farm for which a cotton acreage allotment is established to sell or lease all or any part or the right to all or any part of such allotment (excluding that part of the allotment which the Secretary determines was apportioned to the farm from the national acreage reserve) to any other owner or operator of a farm for transfer to such farm; (2) may permit the owner of a farm to transfer all or any part of such allotment to any other farm owned or controlled by him; Provided, That the authority granted under this section may be exercised for the calendar years 1966 through 1970, but all transfers hereunder shall be for such period of years as the parties thereto may agree.