Uses

NH₄NO₃

Ammonium nitrate has two main uses: fertilizers and explosives.

Fertlizers
There are three major elements needed to increase plant growth: potassium, phosphorus, and nitrogen. Fertilizers are made of combinations of these three elements in order to grow healthier and stronger plants.

Grain farm. How could they get a field this green without fertilizer?

As the world population increase drasticaly, we are constantly trying to find ways to produce more food to keep up with the exponintial growth of the human population. Fertilizer has become and will continue to be an essential part of our existence. The commercialization of fertilizer production can be attributed to Fritz Haber and Carl Bosch for developing the synthesis process for ammonia (See History). This process served as the basis for creating most nitrogen fertilizers. Plants need nitrogen and they absorb it commonly through the nitrate (NO3-) and ammonium(NH4+) ions formed by the disassociation of ammonium nitrate. Because ammonia is an important part in the creation of fertilizers, it has become the 2nd most important chemical in the U.S. Presently, It is the most important source of nitrogen for fertilizers.

Explosives
Ammonium nitrate is also a common component of many explosives. Types of explosives that can contain ammonium nitrate include explosives for wars and for mining. Bombs, explosive shells, torpedoes and missile warheads are all explosive devices used for war purposes. Many of these contain ammonium nitrate. Mining is also an industry where this compound has "triggered" progress. High explosives are required for mining so rock can be broken easily

Ammonium nitrate explosion being used for mining.

and safely. A popular combination of explosives is known as ANFO. It is a mix of ammonium nitrate and diesel fuel oil. It is mainly used for both open pit and underground mining because of its low cost and safety (as compared to other explosives). Often times TNT will be added to mixtures like ANFO in order to make a more powerful explosion.

Other uses include the formation of nitrous oxide. It is formed by dissolving ammonium nitrate (NH₄NO₃) crystals into water, and heating the solution. Yet another use for ammonium nitrate is for cold packs for athletic injuries. A cold pack consists of a block of solid ammonium nitrate and a separate area containing water. The pack is broken to combine the two substances and since the disassociation of ammonium nitrate causes a temperature drop, this is a pratical use for ammonium nitrate.