The Internal Revenue Service's classification of "Agricultural Employees" includes farm workers that raise or harvest agricultural or horticultural products on a farm, including raising livestock. It also includes those who work in connection with the operation, management, conservation, improvement, or maintenance of a farm and its tools and equipment if the major part of such service is performed on a farm.
For this purpose, the term "farm" includes stock, dairy, poultry, fruit, fur-bearing animals, and truck farms, as well as plantations, ranches, nurseries, ranges, greenhouses or other similar structures used primarily for the raising of agricultural or horticultural commodities, and orchards.
Farm work does not include reselling activities that do not involve any substantial activity of raising agricultural or horticultural commodities, such as a retail store or a greenhouse used primarily for display or storage. It also does not include processing services which change a commodity from its raw or natural state, or services performed after a commodity has been changed from its raw or natural state.
See IRS Pub. 51 for more information.