Ammonium nitrate (NH4NO3) is a colorless rhombic or monoclinic crystal at room temperature. It can be decomposed into water and nitrous oxide at 210 °C. Upon severe heating at 300 ℃ above, it undergoes decomposition to form nitrogen, oxygen and water. It is soluble in water, methanol and ethanol.
Ammonium nitrate is one of the major nitrogen fertilizer varieties in the world today as it has no residue in the soil; all of it can be absorbed by crops. Ammonium nitrate is suitable for a wide range of soils and crops but is most suitable for dry and dry crops especially suitable for cash crops such as tobacco, cotton and vegetables.
Ammonium nitrate should not be used as a basal fertilizer, because ammonium nitrate, after being applied to the soil, has its dissociated nitrate ions be easily leached into the soil. At the same time, ammonium nitrate should not be used seed manure because of its higher nutrient content, high hygroscopicity, which will affect the germination upon contact with seeds.
Ammonium nitrate, when applied in paddy field, can have its nitrogen content easily leached. Therefore, its efficiency is not comparable to other nitrogenous fertilizers of equal nitrogen content, being only equivalent to 50% -70% of that of ammonium sulfate with equal nitrogen content. The most ideal application is for top dressing and is most suitable for top-dressing in dry land. The usage amount can be determined according to soil fertility and yield indicators.
There are 2 main methods to produce ammonium nitrate:
Method 1: Neutralisation between nitric acid (HNO3) with ammonia (NH3). The neutralization of 45 - 65% HNO3 with gaseous NH3 is accompanied by the release of 100 - 115 J per mole of NH4NO3. In most processes this considerable heat of reaction is used for partial or complete evaporation of the water. Depending on the pressure and the concentration of the nitric acid, 95 - 97% solutions of NH4NO3 can be obtained.
Method 2: Reacting calcium nitrate tetrahydrate with ammonia and carbon dioxide to form ammonium nitrate and calcium carbonate.