No person may distribute an adulterated soil amendment. A soil amendment shall be deemed to be adulterated if: (1) It contains any deleterious or harmful agent in sufficient amount to render it injurious to beneficial plant or animal life when applied in accordance with directions for use on its label, or if adequate warning statements and directions for use that may be necessary to protect beneficial plant or animal life are not on the label; (2) its composition differs from that which it is purported to be in its labeling; or (3) it contains unwanted crop or weed seed.