Nitrogen-Phosphorus Fertilizers

Ammonium phosphates are produced by reacting ammonia with phosphoric acid or a mixture of phosphoric and either sulfuric or nitric acids. Ammonium phosphates are the leading nitrogen-phosphorus products in the fertilizer industry. High analysis, high water solubility, good physical characteristics, and low production costs are positive features.

Monoammonium phosphate (MAP) (11-52-0) and diammonium phosphate (DAP) (18-46-0) are products of ammonia and phosphoric acid and are available in dry granular form. The liquid formulation (8-24-0) has been replaced by ammonium polyphosphate (10-34-0).

Ammonium phosphate-sulfate (16-20-0 + 15S) or (13-39-0 + 7S) is manufactured by reacting ammonia with a mixture of phosphoric and sulfuric acids. The proportion of these two acids determines the fertilizer grade.

Ammonium phosphate-nitrate (27-12-0 + 4.5S) is made by reacting ammonia with a mixture of phosphoric and nitric acids.

Ammonium polyphosphate is produced by reacting ammonia with superphosphoric acid. This product is most commonly available in fluid form (10-34-0). However, it also can be produced as a dry granular material (11-57-0).

The development of ammonium polyphosphate revolutionized the fluid fertilizer industry. The increased nutrient content resulted in a product that could be produced and handled economically to compete with dry granular formulations. A gallon of 10-34-0 weighs 11.4 pounds and contains 1.1 pounds of nitrogen and 3.9 pounds of phosphate.