(a) Residential property used solely as the principal place of residence of the owner thereof shall be assessed in accordance with its value as a residence, so long as said property is used as the principal place of residence of the owner thereof, and shall not be assessed in accordance with some other method of valuation until said property ceases to be used for such residential purpose.

  (b) Agricultural land, pasture land, timber land, residential and commercial land, excluding structures thereon, used primarily as such, shall be valued for taxation purposes under the provisions of Section 5 of this Article, upon the basis of its agricultural, pasture, timber, residential, or commercial productivity or use, and when so valued, such land shall be assessed at the same percentum of value and taxed at the same rate as other property subject to ad valorem taxes.

  (c) The General Assembly shall enact laws providing for the administration and enforement of this Section and for the imposition of penalties for violations of this Section, or statutes enacted pursuant thereto.

[Added by Const. Amend. 59.]