- Nitrogen gas, N2(g), is the major constituent of air, ~78% by volume.
- Inorganic (non-carbon) compounds of nitrogen are not commonly found as minerals because most of them are water soluble.
In dry climate locations there are beds of nitrates.
- Nitrogen is found combined in organic (carbon) compounds in all living matter, both plant and animal.
- Nitrogen in the atmosphere is the source of all nitrogen found in living matter.
- The complex interrelationship between atmospheric nitrogen, nitrate, nitrate and ammonium ions found in soils, and organic nitrogen compounds found in living matter, is called the nitrogen cycle.
- The nitrogen cycle keeps the nitrogen content of the atmosphere constant.
- Nitrogen fixation refers to the conversion of nitrogen gas into nitrogen compounds.
- Nitrification is the process of converting one nitrogen compound to another.
- Denitrification is the process of releasing nitrogen gas back into the atmosphere.