The nitrogen cycle provides nitrogen to the ecosystem from the atmosphere, ground and oceans. Nitrogen is an important component of complex molecules such as amino acids and nucleotides, which lead to the creation of proteins and DNA, the building blocks of all life .
I would go with mathmatical formula because of physics and what not but I'm not completely sure so if you have a different possible answer you think would be better, go with that :)
Can you provide more details so that I can answer your question properly?