A major use of ammonia is in the manufacture of fertilisers. The most effective fertilisers contain nitrogen because plants need it in order to produce proteins. Phosphorus and potassium are also essential elements commonly found in fertilisers. Using artificial fertilisers has advantages and disadvantages.
Many fertilisers are ammonium salts. They can also be made from ammonium hydroxide (ammonia solution). If ammonium hydroxide is used, water is also produced in the neutralisation reaction.
Ammonia + nitric acid → ammonium nitrate
NH3 + HNO3 → NH4NO3
Ammonium hydroxide + nitric acid → ammonium nitrate + water
NH4OH + HNO3 → NH4NO3 + H2O
Ammonia + sulfuric acid → ammonium sulfate
2NH3 + H2SO4 → (NH4)2SO4
Ammonium hydroxide + sulfuric acid → ammonium sulfate + water
2NH4OH + H2SO4 → (NH4)2SO4 + H2O