| Agricultural Uses | Ammophos is the trade name of one of the most popular
brands of ammonium phosphate fertilizers. It contains
16% nitrogenand 20% phosphorus (as P2O5).
Ammophos is made by ammoniating a mixture of
sulphuric and phosphoric acids. After ammoniation, the
slurry formed is granulated in a pugmill or a drum unit,
dried, and screened to give a product that is two-thirds by
weight of ammonium sulphate and one-third that of
ammonium phosphate. This water-soluble product has
good storage properties.
Two grades of ammonium phosphate are known. One
contains 11 % nitrogen and 48 % phosphorus (as P2O5),
the other contains 16.5% nitrogen and 20% phosphorus
(as P2O5). The first grade is made by neutralizing
phosphoric acid with ammonia, and the other is made by
neutralizing a mixture of phosphoric and sulphuric acids
with ammonia. The first grade of ammophos has a
theoretical lime requirement of 5 kg of calcium carbonate
per kg of fertilizer, which indicates the acid forming
nature of the fertilizer.
Ammonium dihydrogen phosphate sulphate is also
called ammoniated sulphate. It is a double salt of
ammonium dihydrogen phosphate, NH4(H2PO4) and
ammonium sulphate, (NH4)2SO4, and is formed by
neutralizing a mixture of sulphuric acid and phosphoric
acid by gaseous ammonia. |