The City of Frederick by action of the board of aldermen may exempt from taxation all agricultural property within the city or may levy a lower tax rate thereon than is levied on other property within the city. For the purposes of this section, agricultural property shall include all unimproved land used exclusively for agricultural purposes, all barns, stables, and similar improvements located thereon, and all farming implements and stock used in connection therewith. Nothing in this section shall be deemed to permit the exemption from taxation or the levying of a lower tax rate on any dwellings or improvements other than those mentioned above and the land on which these are erected and the curtilage and garden used in connection therewith. (Acts 1951, Ch. 539, § 109)