The Microbial World: The Nitrogen Cycle and Nitrogen Fixation
- How nitrogen gets "fixed" by bacteria to become available for plants on earth.
- http://www.biology.ed.ac.uk/research/groups/jdeacon/microbes/nitrogen.htm

The Nitrogen Cycle
- Diagram and explanation of the cycle.
- http://www.physicalgeography.net/fundamentals/9s.html

Nutrient Overload: Unbalancing the Global Nitrogen Cycle
- Shows how nutrient pollution through man can lead to algae blooms that unbalance the cycle.
- http://pubs.wri.org/pubs_content_text.cfm?ContentID=1412

Animation of Nitrogen Cycle
- Presents an active diagram of this process, together with a description of each stage and component.
- http://www.sp.uconn.edu/~terry/229sp03/lectures/Ncycleanim.html

Nitrogen Cycle
- Diagram, facts, nitrogen fixation methods, and what fixes nitrogen.
- http://homepages.nyu.edu/~pet205/nitrogen.html

Streams Reduce Nitrogen Pollution, Scientists Find
- Article describing the finding of scientists that small streams are extremely efficient at removing some of the excess nitrogen that is flowing into waterways, endangering fish and other forms of aquatic life.
- http://news.nationalgeographic.com/news/2001/05/0504_smallstreams.html