Ammonium sulphate

Ammonium Sulfate . Ammonium Sulfate (SA) is the only single granular nitrogen fertilizer, with sulfur (S) and calcium (CaO) in the same granule.


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  • 1 Features
  • 2 Physical Properties
  • 3 Chemical Properties
    • 1 Manufacture
  • 4 Commercial Products
  • 5 Uses, applications and recommendations
  • 6 Mix compatibility
  • 7 Source.


Chemical Name: Ammonium Sulfate Other Names: Ammonia Sulfate, Sulfur Salt and Ammonium Chemical Formula: ((NH4) 2 SO4) Molecular Weight (g / mol): 132.14

Physical Properties

  • Appearance: In their pure state they are white crystals in the form of diamonds (Plates, agglomerates), but in a commercial state of fertilizer, theypresent a slight yellow tone due to Arsenic Sulfide (from coke ovens).
  • Density: In its pure state it is 1.77, but agricultural ammonium sulfate has a bulk density without weighing it down, from 0.8 to 1.1.
  • Solubility: In water it is very large and increases considerably with temperature. The solubility in kg of ammonium sulfate per Lt of water is: at 0 ºC, 70.6; at 20 ºC, from 75.4; at 60 ºC, from 88.0 and at 100 ºC, from 103.3.
  • Hygroscopicity: typical of ammonium sulfate is not very high, being the critical atmospheric humidity of 70%, but it can increase if there is free sulfuric acid, whose avidity for water is very high. Hygroscopicity index at 30 ºC = 20.
  • Reaction of the fertilizer: Acid. Acidification index = 110
  • Salinity: Salinity index = 69.

Chemical properties

It is the result of the action of a strong acid (sulfuric) on a weak base (ammonia). This explains why their solutions are partially hydrolyzed and have a slightly acidic reaction. For the same reason, the boil makes them give off ammonia. Ammonium sulfate can find strong oxidants, such as chlorates, explosive mixtures.

Decomposes in heat (at elevated temperature) with loss of NH3. It decomposes easily at normal temperature with alkaline products and with ammonia evolution .


  • Treatment of a suspension of calcium sulfate with ammonia and acid and carbonic acid:

The insoluble calcium carbonate is separated by filtration from the ammonium sulfate solution, from which it is extracted by evaporation

CaSO4 + 2 NH3 + CO2 + H2O ————— NH4 (SO4) + CO3Ca

  • Reaction of sulfuric acid with ammonia, which can be of synthesis or recovery (coal distillation and purification of gas from lighting)

2NH3 + SO4 (NH4) 2 ——————- SO4 (NH4) 2

Commercial products

Agricultural ammonium sulfate comes commercially in the form of:

  • Synthetic sulfate, 21% N
  • Recovery sulfate: from 20.5 to 20.8% N

The properties are very similar to those of ammonium sulfate.

Uses, applications and recommendations

Product exclusively for agricultural use. It is a direct application fertilizer; excellent “start” or “bottom” fertilizer at planting time. It is the Ammonium Sulfate fertilizer suitable for all types of terrain and crops; controlled release (immediate action and long-acting) with good storage qualities. Because it is a fertilizer with nitrogen and sulfur in higher concentration, calcium slightly modifies the PH of the soil in the laying area, so that calcium is the best used by the crop.

Due to its magnificent granular presentation, its hygroscopicity is lower than that of common ammonium sulfate. Its fluidity and chemical stability are excellent; which facilitates the preparation of fertilizer formulas in physical mixtures and their mechanical manual application.

The nitrogen and phosphorus , influence growth and development of the foliage, roots and stems of plants, and the optimum growth of microorganisms; sulfur is part of the sulfur amino acids found in proteins.

Calcium influences the quality of the product and resistance of the fruits or damage by pests. The sulfate Granular ammonium is not lost by leaching because of the absorption of the ammonia by soil colloids and controlled degradation. To know how much to apply of granular SA, consult our technical staff.

Mix compatibility

It can be mixed with natural phosphates, phosphaphase and dicalcium phosphate without any precaution. It is recommended not to prepare until the last moment the mixtures are silvinite, potassium chloride, potassium sulfate and superphosphates, due to the risk of setting during storage.

It is also necessary to avoid mixing ammonium sulfate, except at the time of use, with alkaline products such as lime and dephosphorous slag, to avoid possible nitrogen losses. The addition of chlorate herbicides should also be avoided, due to the danger of explosion.


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