Explain the Nitrogen cycle

Answer 1

There are many sources online written at various grade levels. Perhaps this one will help:
http://www.elmhurst.edu/~chm/onlcourse/chm110/outlines/nitrogencycle.html

I recommend reading several that you easily find by using the search words "nitrogen cycle" . You will probably find one to your liking.

Answer 2

Already answered.

http://www.jiskha.com/display.cgi?id=1352679613