Any ordinance or resolution of any unit of local government that makes the operation of any agricultural operation a nuisance or provides for the abatement thereof as a nuisance under the circumstances set forth in this chapter is void, except that the provisions of this section shall not apply when a nuisance results from the negligent or improper operation of any such agricultural operation or from an agricultural operation located within the corporate limits of any city as of July 1, 1981.