This act is supplemental to the provisions of the laws of this state which authorize counties to adopt zoning regulations for all or any part of the land located within the county and outside of any incorporated city, which laws are specifically Kan. Stat. Ann. §§ 19-2901 to 19-2937, inclusive, and amendments thereto. All city zoning regulations and the authority of any city to adopt zoning regulations for land located outside the city shall cease and terminate as to any tracts of land lying within such area on the date the county places in effect zoning regulations governing the same tracts of land which are in reasonable conformance with a comprehensive plan and have been adopted in conformity with the appropriate statutes set forth in this section.