Dear Sir / Madam,

 what is organic nitrogen? Can you please include a video for nitrogen fixation and make the concept a little more clear?

The nitrogen obtained from the living organisms is known as organic nitrogen. In otherwords the nitrogen combined in the organic molecules like proteins and amino acids present in living organisms is termed a organic nitrogen. 

We keep on adding videos and animations time- to -time based upon on students' requests. We have taken your suggestion into consideration and will try to work on it. Keep posting!