It is well-known that it is not practical to produce an NP fertilizer by simply mixing superphosphate, especially SSP and urea because of quality problems with the final mixture during storage (formation of dust, caking).
The USP modification of the Casale superphosphate process makes it possible to obtain, straight from the plant outlet, a powdered urea-based 20-10-0 NP fertilizer with a high P2O5 water-solubility after a very short curing time. The raw materials needed are urea, phosphate rock and sulphuric acid.
Thanks to this original process there are no secondary reactions during storage.
The agronomic efficiency of USP has been demonstrated on both rice and maize: a given crop yield can be achieved using 10% less nitrogen than when urea and a phosphate are applied separately.
As with SSP and TSP, if a granular USP product is desired, the powder product can be granulated (alone or with other raw materials) in a conventional fertilizer granulation unit.