Notwithstanding the provisions of sections 471.38 to 471.41, when purchases and agreements have been authorized and when vendor discounts are available thereunder to the county upon early payment, the administrator shall have authority to authorize such early payment without prior board approval. Authority hereunder may only be exercised when purchases and agreements have been approved by the board and contain provisions permitting discounts for early payment. When early payment is made, the board shall ratify such action and record it in the official proceedings of the board.