Nitrogen Controversy

Dr. Ian Mulleins, a member of the United States Agricultural Research team, plans an initiative to examine the long-term effects of chemically manufactured nitrogen fertilizers. Recently he noted that the U.S. is producing so much artificially fixed nitrogen for agriculture that nearly one-third of all nitrogen content in the human body comes from artificial sources!

What We Need to Know

What is the source of artificially fixed nitrogen?
Why is nitrogen used in fertilization of crops?
How much does the agriculture industry depend on artificial nitrogen sources?
Review the nitrogen cycle to determine where natural nitrogen comes from.
Where is nitrogen used in plant and body structures?

What has had politicians in Washington concerned lately has been the population explosion worldwide. India just reached the 8 billion persons mark! Dr. Mulleins believes that it is the great success of agribusiness and an abundance of food that are responsible ultimately for the overpopulation. The use of artificial sources of nitrogen has allowed farmers and crop growers to cultivate more food than can be eaten. Dr. Mulleins demonstrated evidence of his ideas in the following Graphs 1 and 2. The data demonstrate that world population growth over time corresponds with an increase in the use of nitrogen fertilizer.

Graph 1. World Population from 1900 to 2000.

Graph 2. Amount of Nitrogen Fertilizer Consumed from 1900 to 2000.

What We Need to Know

Could there have been other factors that could explain world population growth?
What are the factors that control populations?
Would these factors apply to animals other than humans?

A Proposal of Significance

Dr. Mulleins has written a report requesting that the U.S. Department of Agriculture start to limit the amount of artificial nitrogen produced for fertilizer. His research team identified a number of advantages and disadvantages of producing artificial fertilizer. Examine the following lists.

Advantages

Disadvantages

Crop growers grow more food

Population continues to grow dramatically

Crop growers produce medicines and fibers

Artificial nitrogen causes diseases in infants

Areas of high population density are able to survive

High nitrate levels linked to cancer

Ranchers can grow a high protein diet for livestock

Leaching can contaminate ground andsurface water where fertilizer is used heavily

Nitrogen in ponds and lakes causes eutrophication

Assignment

Weigh the advantages and disadvantages. Determine which way you would vote if you were asked to decide on this issue.
How does crop nitrogen get into ground and surface water supplies?
What is eutrophication and why is it a problem? What could be the long-term effects of contaminated water?
What are other ways that soil can be fertilized without using artificially produced nitrogen fertilizer?
If growing vegetables without the use of artificial nitrogen means an increase in the prices of produce, would you pay the higher prices if it means benefiting the environment. Support your answer with rationale.

RESOURCES

Smil, Vaclav. 1997. Cycles of Life. Scientific American Library. W.H. Freeman and Co.

Smil, Vaclav. 1997. Global Population and the Nitrogen Cycle. Scientific American. July, pp. 76-81.

Galloway, James N.; William H. Schlesinger; Hiram Levy II; Anthony Michaels; and Jerald L. Schnoor. 1995. Nitrogen Fixation: Anthropogenic Enhancement--Environmental Response. Global Biogeochemical Cycles. Vol. 9 (2):235-252.

Van der Voet, Ester; Rene Kleign; and Udo de Haes. 1996. Nitrogen pollution in the European Union: origins and proposed solutions. Environmental Conservation. Vol. 23 (2):120-132.

Smil, Vaclav. 1991. Population growth and nitrogen: an exploration of critical existential link. Population and Development Review. Vol. 17 (4):569-601.

Derse, Phillip. 1971. The Carbon Dioxide System and Eutrophication. Madison: WARF Institute.

Sellers, B. 1987. Decaying Lakes. John Wiley and Sons. New York.

http://www.grida.no/soeno97/eutro