Straight fertilizers containing a single nutrient (nitrogen, phosphorus, or potassium) are classified in specific headings by nutrient type, while mixed or compound fertilizers containing two or more nutrients fall under heading 3105. The nutrient ratios and whether the product is in tablet or similar form can further affect the specific subheading, making lab analysis documentation useful at entry.

Nitrogen fertilizer prices track natural gas costs closely, since ammonia synthesis is energy-intensive; supply disruptions in major gas-producing regions ripple quickly into urea and UAN markets. Phosphate fertilizer availability is tied to phosphate rock mining concentration in a handful of countries. Importers managing seasonal agricultural demand often use forward contracts and multiple-origin sourcing to hedge against these volatility factors.