(a) General rule.--No person shall distribute an adulterated soil amendment or plant amendment product. A soil amendment or plant amendment shall be deemed to be adulterated if:
(1) it contains any deleterious or harmful substance in sufficient amount to render it injurious to beneficial plant life, animals, humans, aquatic life, soil or water when applied in accordance with its intended use or directions for use on the label;
(2) adequate warning statements or directions for use which may be necessary to protect plant life, animals, humans, aquatic life, soil or water are not shown upon the label;
(3) its composition falls below or differs from that which it is purported to possess by its labeling; or
(4) it contains viable weed seed in amounts exceeding the limits which the department establishes by regulation.
(b) Exception.--A soil amendment or plant amendment shall not be considered adulterated under this section if the quantity of the substance in the soil amendment or plant amendment does not ordinarily render it injurious.