Readings: Session 12
- Keeney, D.R., and J.L. Hatfield. The nitrogen cycle, historical perspective, and current and potential future concerns. In: Follett, R.F., and Hatfield, J.L. Nitrogen in the Environment: Sources, Problems, and Management. 2001.
- Foth, H.D., and Ellis, B.G. Soil Fertility, 2nd.ed. Chapter 6. Nitrogen (part). 1997.
- Council for Agricultural Science and Technology, “Gulf of Mexico Hypoxia: Land and Sea Interactions,” Task Force Report, June 1999.
The Nitrogen Cycle, Historical Perspective, and Current and Potential Future Concerns
- How does the amount of nitrogen brought into global circulation from anthropomorphic sources compare to that which is fixed naturally?
- Which human activity brings the maximum amount of fixed nitrogen into circulation?
- What are the local and global consequences of the increased N levels in our surroundings?
- What is the MCL allowed for nitrate nitrogen in drinking water? What are the arguments against this levels?
- What factors complicate regulation of N levels in ground water?
- Which are the nutrients of concern when we consider the problem of eutrophication and hypoxia in freshwater, and, ocean and estuaries?
- What factors affect movement of nitrogen into ground and surface waters?
- What is the general use of nitrogen use and manure production in the US over the 15 years?
- What different routes does the author suggest for improving nitrogen fertilizer use efficiency?
- What are the major storehouses of nitrogen?
- What are the dominant forms of nitrogen in soils?
- What is the importance of biologically fixed nitrogen with reference to the overall amount of nitrogen that is added to soils?
- What is the difference between symbiotic and non symbiotic nitrogen fixation? What are some of the examples for the two different mechanisms?
Gulf of Mexico Hypoxia
- What conditions define hypoxia?
- What are the factors causing hypoxia?