Ammonia, NH3, is an important raw material in the manufacture of fertilisers. Some ammonia is converted into nitric acid which itself is used in the manufacture of fertilisers and explosives. Ammonia is also a useful ingredient in some cleaning fluids.
Ammonia is a vital route by which nitrogen in the air can be made available to plants to enable them to build protein molecules. Plants cannot use nitrogen directly from the air. They need nitrogen compounds, dissolved in water, which they absorb through their roots.
Without synthetic, ammonia-based fertilisers, the world would be unable to grow enough food to feed its population.