Double salts and blended mixtures of ammonium sulfate and ammonium nitrate occupy a distinct classification niche from either straight ammonium nitrate or straight ammonium sulfate, because the combined nitrogen-sulfur nutrient profile targets crops with elevated sulfur demand such as canola, alfalfa, and small grains. The classification boundary between this heading and adjacent nitrogenous fertilizer categories turns on the specific salt chemistry and blend ratios, making laboratory analysis or supplier certification useful documentation at entry. Importers should also confirm whether any active antidumping or countervailing duty orders on ammonium nitrate-containing products extend to these mixtures, as scope rulings can be product-specific.

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