Nitrogen as a gas is relatively inert, but some nitrogen is also vital to life as part of amino acids, the building blocks of proteins. Thus, all living things are made up of compounds including nitrogen, oxygen, hydrogen and carbon. Each of these comes from the air and water around us. Nitrogen from the air cannot be used directly by plants, so they rely on getting it from soluble nitrogen compounds instead. Each molecule of nitrogen is made up of twonitrogen atoms linked together extremely strongly.
Nature provides two fixing mechanisms.
One occurs whenever lightning flashes and heats up the air. To make use of nitrogen as a fertiliser, people have to dig up rocks containing nitrogen compounds, find chemical ways to make nitrogen compounds or grow legumes in rotation with other plants. This is why nitrogen compounds are favoured as raw materials for explosives, from gunpowder to nitroglycerine. In a nitrogen molecule. Nitrogen was one of the first gases to be formed in the early atmosphere, some four billion years ago.