Solution:
Nitrogen is important because, it helps us grow crops, and it produces grass for animal. It comes from lightning and is named nitrogen fixation
By which free nitrogen (N2) is extracted from the atmosphere and converted (fixed) into nitrogen compounds which are plant nutrients (fertilizer). In nature, this process is carried out by certain bacteria (present in the root nodules of legumes such as beans and peas), blue-green algae, and the lightning flash.
Thus the Nitrogen form the atmosphere the biotic part to the ecosystem converted into the biotic part.