Under SITC 56294, mixtures of monoammonium phosphate and diammonium phosphate are explicitly included in the MAP heading rather than the DAP heading. At the HTS level used for US customs entry, the specific composition ratio and the applicable tariff schedule notes govern classification, so a certificate of analysis and consultation with a licensed customs broker are advisable for mixed-product shipments.

MAP is preferred when soil pH management is a concern, as it has a more acidifying effect than DAP, and when a higher phosphorus-to-nitrogen ratio is agronomically required. DAP is more common in broad-acre grain programs. Blenders often combine both to hit a target N-P ratio, which is why the mixture category exists as a distinct trade classification.