Section 13(b)(15) of the Fair Labor Standards Act exempts from the overtime requirements of section 7:
Any employee engaged in ginning of cotton for market, in any place of employment located in a county where cotton is grown in commercial quantities, or in the processing of sugar beets, sugar-beet molasses, sugarcane, or maple sap, into sugar (other than refined sugar) or syrup.
Section 13(b)(15) supplants two exemptions that were contained in the Act prior to the Fair Labor Standards Amendments of 1966. The first is former section 13(a)(18), having identical language, which provided a complete exemption for those employed in the ginning of cotton. The second is the former section 7(c) which provided an overtime exemption for the employees of an employer engaged in sugar processing operations resulting in unrefined sugar or syrup.