Nitrogen makes up about 78% of the earth’s atmosphere however the atmosphere of
Mars contains less than 3% nitrogen. The element seemed so inert that Lavoisier
named it azote, meaning "without life". However, its compounds are vital components
of foods, fertilizers, and explosives. Nitrogen gas is colourless, odourless, and
generally inert. As a liquid it is also colourless and odourless.
Nitrogen is "fixed" from the atmosphere by bacteria in the roots of certain plants such
as clover, hence the usefulness of clover in crop rotation.