With the approval of the Department of Agriculture and the State Public Works Board, the amount paid into the Fair and Exposition Fund shall be available for expenditure by the county for permanent improvements for fair purposes on the property of the county, the purchase of equipment for fair purposes, or the acquisition or purchase of real property, including costs of appraisal or other incidental costs, to be used as sites for such permanent improvements. Any portion of such funds which is not so expended within three years after being paid into the State Treasury shall be added to and become a part of the amount available under law for permanent improvements upon the property of the state, citrus, county, or district agricultural associations for fair purposes, or the purchase of equipment for fair purposes, or the acquisition or purchase of real property and appraisal or other incidental costs, to be used as sites for such permanent improvements, in such amounts as are allocated by executive order of the Director of Agriculture.