(1) Upon the filing of such petition in the district court, the judge thereof shall set a date for a hearing, not less than forty days nor more than sixty days thereafter. It is the duty of the clerk of said court to cause a copy of such petition and a notice of the date and the time set for such hearing to be served upon the mayor of the city. The same shall be served at least thirty days prior to the hearing of such petition by the court. Upon the hearing and proof of the facts set forth in said petition, it shall be determined whether said tracts of land should be disconnected from such city, and the court shall enter an order or decree accordingly. When a city has maintained streets, lights, and other public utilities for a period of three years through or adjoining said tracts of land, the owners shall not be entitled to disconnect the land under the provisions of this part 6.
(2) If an area has been annexed to a city for a period of two years and then successful action is undertaken to disconnect such area, the zoning placed on the area by the city shall remain in force and effect after disconnection unless and until changed by the county.