(a) Prohibition.--No person may distribute a fertilizer that is adulterated. A fertilizer shall be deemed to be adulterated if any of the following apply:
(1) It contains a deleterious or harmful substance in any 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 that may be necessary to protect plant life, animals, humans, aquatic life, soil or water are not shown on the label.
(3) Its composition falls below or differs from that which it is purported to possess by its labeling.
(4) It contains viable weed seed or unwanted crop seed in amounts exceeding the limit that the department establishes by regulation.
(b) Exception.--A fertilizer shall not be considered adulterated under this section if the quantity of the substance in the fertilizer does not ordinarily render it injurious.