(1) In respect of every loan raised by a Board under this Act, which is not repayable before the expiration of one year from the date of the loan, the Board shall set apart half-yearly out of its income as a sinking fund a sum sufficient to liquidate the loan within a period which shall not in any case, unless the previous consent of the Central Government has been obtained, exceed thirty years; but the maximum period shall not in any case exceed sixty years:
     Provided that a sinking fund need not in the absence of any stipulation to that effect be established in the case of loans taken by the Board from the Central Government or any State Government.
     (2) Where any sinking fund has, before the appointed day, been established by any authority in respect of a loan raised by it for which loan the Board is liable under this Act, the sinking fund so established by that authority shall be deemed to have been established by the Board under this section.