Diammonium phosphate (DAP 18:46:0) is one of a series of water-soluble ammonium phosphate salts which can be produced when ammonia reacts with phosphoric acid.
Di-Ammonium Phosphate, analysis 18-46-0, is the world’s most widely used ammo-phos fertilizer. DAP is easily adapted to all ranges of dry fertilizer application methods. DAP is a perfect choice, as a base product for custom blends. The high analysis of 18-46-0, also aids in reducing handling, freight, and application costs.
DAP is used as a fertilizer. When applied as plant food, it temporarily increases the soil pH, but over a long term the treated ground becomes more acidic than before upon nitrification of the ammonium. It is incompatible with alkaline chemicals because its ammonium ion is more likely to convert to ammonia in a high-pH environment.
Nutrients include P2O5 (46%) and Ammonical Nitrogen (18%). DAP provides the correct proportion of phosphate and nitrogen needed for farming wheat, barley and vegetables. It is also applied in the early stage of fruit orchard fertilization.
Rock phosphate is the raw material used in the manufacture of most commercial phosphate fertilizers on the market. In the past, ground rock phosphate itself has been used as a source of P for acid soils. However, due to low availability of P in this native material, high transportation costs, and small crop responses, very little rock phosphate is currently used in agriculture.
The manufacture of most commercial phosphate fertilizers begins with the production of phosphoric acid. A generalized diagram showing the various steps used in the manufacture of various phosphate fertilizers is provided in Figure 1. Phosphoric acid is produced by either a dry or wet process. In the dry process, rock phosphate is treated in an electric furnace. This treatment produces a very pure and more expensive phosphoric acid (frequently called white or furnace acid) used primarily in the food and chemical industry. Fertilizers that use white phosphoric acid as the P source are generally more expensive because of the costly treatment process.