The two products occupy separate subheadings — 310420 for potassium chloride and 310430 for potassium sulfate — and may carry different duty rates and trade-remedy exposure. The chemical composition (chloride vs. sulfate anion) is the classification criterion, confirmed by the product's chemical specification or certificate of analysis. Antidumping orders have targeted MOP from specific origins, so the distinction also has significant duty-liability implications.

Canada's Saskatchewan basin holds some of the world's largest and highest-grade potash deposits, giving Canadian producers a structural cost and proximity advantage for US buyers. This concentration means US agricultural supply chains are sensitive to Canadian production disruptions, rail logistics constraints, and any changes in trade policy between the two countries.