Both SSP and TSP fall within the superphosphate fertilizer heading, but they differ significantly in P₂O₅ content — SSP typically contains around 16–20% P₂O₅ while TSP contains 44–48%. At the HTS level, these grades may be separated into distinct tariff lines, and antidumping duty orders may define scope by P₂O₅ concentration or by production method. Importers should confirm which grade their product represents and whether it falls within the scope of any active order.

Superphosphate production is upstream-constrained by phosphate rock mining, which is geographically concentrated in a small number of countries. Disruptions to rock supply — whether from export restrictions, mining capacity changes, or logistics bottlenecks — can ripple quickly into superphosphate availability and pricing. Importers with large seasonal procurement needs often use forward contracts or maintain safety stock to buffer against supply interruptions.