Any irrigation district organized or hereafter organized under the laws of the state of Idaho is hereby authorized and empowered to purchase state lands within the boundaries of such irrigation district from the state at the state sale of said lands and may sell and dispose of the lands so purchased at a price and upon terms to be determined by the board of directors of such district. Any irrigation district, as a purchaser of any state lands within the boundaries of such district, shall be entitled to the same rights as a private purchaser and a title so acquired by the district may be conveyed by deed executed and acknowledged by the president and secretary of the board of directors: provided, that authority to so convey must be conferred by resolution of the board entered on its minutes: provided further, that in the sale by the state of state lands within an irrigation district under this chapter the lands shall be offered in tracts or parcels of not more than six hundred forty (640) acres.