Nitrogen is available in the earth's atmosphere by 78 % as N2 gas.
In nitrogen fixation, bacteria convert nitrogen gas into ammonia or usable form of nitrogen used by plants., When animals eat the plants, they acquire usable nitrogen compounds.
During the nitrogen cycle, nitrogen atoms used in the cycle are neither created or destroyed, or changed into other atoms.
Thus it can be said that the law of conservation of matter is related to the nitrogen cycle, which states that matter is never created or destroyed in any chemical or physical process.
