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THIRD QUANTITATIVE EXERCISE:
NITROGEN: PROTEIN AND MANURE
DUE IN CLASS ON TUESDAY, MAY 13 AT 1:30 p.m.
This is one of four quantitative exercises, of which you must choose three.
Your task here is to one of the practical implications of the discussions about nitrogen, chemical fertilizers, world food supply, fossil fuels, carbon budgets, etc., that thread their way through our case study on farming.
Consider the following propositions:
- Dairy foods are the most efficient way to deliver protein to human diets.
- Dairies produce enormous amounts of manure in concentrated areas
- Manure is high in nitrogen, and is thus a good fertilizer, but is also harmful if released into bodies of water.
- Growing grain to feed cows requires nitrogen fertilizer
- Pastures also grow faster if fertilized
- Manure is heavy and much more expensive to transport than other fertilizers
With these facts in mind (and numbers gleaned from Smil, from a study on nitrogen availability and the reference it links to) figure out whether Western Washington could supply all the protein needs of its population just from its dairy farms (remember dairy cattle are slaughtered for hamburger after 4-6 years), whether, in this case, there is a use for all the manure that these farms generate, and if not, what would be the costs of disposing of this manure?
This exercise is designed, more than anything to show you the difficulty of modeling even a small part of an ecosystem. Obsess for awhile on what variables you need to measure, compare current values with what would be needed in the ideal scenario of efficient protein conversion, and then do the numbers. Do not obsess too long; the point is to try the exercise, not to come up with a definitive answer.
Points for doing effective quantitative exercises:
- Each quantitative exercise should be no more than 3 pages in length. I will not read page 4.
- References can be in any standard footnote, endnote, or embedded reference format. If you use endnotes or embedded references, the notes or bibliography may appear on page 4.
- Each exercise should consist of the use of data, calculations, and statistics of your own choosing to illustrate a point about the environmental problem posed.
- Exercises will be graded on reliability of the data used; appropriateness of specific data, calculations, and statistics to the problem posed; accuracy of calculations, and persuasiveness of arguments made on the basis of the calculations.
- Remember: Figures are human creations. How your calculations come out depends not only on the accuracy and completeness of your data and on how well you do your calculations, but also on how you frame the question and how you interpret the data and the calculations. For this reason, some of your exercises include the requirement to reflect on your own biases in selecting your particular data and in doing the calculations the way you did.
Processes and grading:
- All the quantitative exercises are due at the beginning of a class. You should print out your exercise and bring it to class that day; we will spend the first 25-30 minutes of the class going over the exercise. You should also turn it in electronically to the instructor before the beginning of class. If you have drawings, etc., you can scan and send as a .jpg or, better yet, if you have the capability to do that, as a .pdf.
- I will grade and return exercises, with comments, within one week of the due date.
- A is 4.0, A- is 3.7, B+ is 3.3, B is 3.0, etc.
- Late exercises will be graded down one letter-scale point (A to A-, B- to C+) at 1:30 p.m. on the due date, and one more letter-scale point for each additional calendar day they are late.
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