Limitation on power of certain public agencies to impose benefit assessments or special ad valorem levies. No political subdivision providing public services such as sewer, water or lights or for non-farm drainage may impose benefit assessments or special ad valorem levies on land used for primarily agricultural production within an agricultural area on the basis of frontage, acreage, or value, unless such benefit assessments or special ad valorem levies were imposed prior to the formation of the agricultural area, or unless such service is provided to the landowner on the same basis as others having the service.