Va. Code § 3.2-301
In order to limit the circumstances under which agricultural operations may be deemed to be a nuisance, especially when nonagricultural land uses are initiated near existing agricultural operations, no locality shall adopt any ordinance that requires that a special exception or special use permit be obtained for any production agriculture or silviculture activity in an area that is zoned as an agricultural district or classification. Localities may adopt setback requirements, minimum area requirements, and other requirements that apply to land on which agriculture and silviculture activity is occurring within the locality that is zoned as an agricultural district or classification. No locality shall enact zoning ordinances that would unreasonably restrict or regulate farm structures or farming and forestry practices in an agricultural district or classification unless such restrictions bear a relationship to the health, safety, and general welfare of its citizens. This section shall become effective on April 1, 1995, and from and after that date all land zoned to an agricultural district or classification shall be in conformity with this section.
Va. Code § 3.2-301