Target Grade Level / Age Range:

9 th-12 th Grades


50 minutes


Students will gain an understanding of the nitrogen cycle and why farmers practice crop rotation or choose to fertilize.


  • Set of Nitrogen Reservoir Cards-11
  • Set of Nitrogen Passports - 1 per student
  • Dice - 11
  • Stamps or markers - 11

Suggested Companion Resources (books, websites, etc.)

Vocabulary (with definitions)

  • Nitrogen Fixation:  The process of converting nitrogen gas into biologically available nitrogen
  • Ammonification:  Prokaryotes and fungi convert the nitrogen compounds in animal waste and dead organic matter into ammonia.
  • Nitrification: The process (mostly from prokaryotic bacteria) that converts ammonia to nitrate and then nitrite.
  • Denitrification:  The process that converts nitrate to Nitrogen gas making it biologically unavailable.
  • Biogeochemical Cycle: The pathway by which a chemical substance moves through both biotic and abiotic compartments on earth.
  • Yield: the amount of product produced per acre, measured in bushels

Interest Approach or Motivator:

To introduce this lesson, start the students with a problem to solve.  A farmer has a field with very poor corn yields.  It has been diagnosed with nitrogen deficiency.  Rather than yielding 200 bushels per acre, the farmer’s field is only yielding 140 bushels per acre. His field is 70 acres. At the current price of corn (have students research), how much money is he losing on this field?

Have students do the calculations individually, and then discuss as a class. If it costs $140 per acre to fertilize his field, is it worth the extra money? Why or why not?

Background – Agricultural Connections (what would a teacher need to know before teaching this lesson):

Nitrogen in the form of ammonium (NH 4 +) and nitrate (NO 3 -) are useable by plants. Nitrogen gas (N 2) is the most abundant gas in the atmosphere but is inaccessible to plants and animals. Bacteria, animal waste, and dead plants/animals provide usable sources of nitrogen.

Nitrogen is found in many places in the environment and cycles constantly in different forms.

Legumes, such as soybeans, harbor nitrogen fixing bacteria on their roots which can naturally fertilize the soil.  Nitrogen can be made as synthetic fertilizer which can be added to amend the soil.

Nitrogen is needed by living things to make nucleic acids like DNA, proteins, and enzymes.  It aids in the growth of plants.


  1. Before students arrive, hang or place the 11 nitrogen reservoir posters around the room.
  2. Display the economic impact of nitrogen poor crops, and explain what the difference in income would be from a healthy field of corn vs. a lower yielding nitrogen deficient field.  Have students jot down a quick list of other factors that could influence the yield.  Ask a few to share.
  3. Explain that each student will be an atom of nitrogen and will get a passport to stamp as they travel through the cycle.  They all pick a place to start.  Each poster has a number code and a die to roll.  It tells them where to go next.  There they will stamp their passport, roll the die, and travel on till their passport is full.
  4. Questions for discussion when they return to their seats could include:
    1. Does the cycle have a beginning and/or an end?
    2. Share with your table group the most surprising or interesting move you made as a nitrogen atom.  Was your journey similar or different from theirs?
    3. What is the significance of a lot of nitrogen ending up in the same place at once?
    4. What role to legumes such as soybeans play in the nitrogen cycle?
    5. How do humans influence this cycle either unknowingly or on purpose?
    6. How does the nitrogen cycle affect agriculture?
    7. How might farmers work with the nitrogen cycle to ensure their plants get the nitrogen they need?
  5. The passport also contains spaces to identify the form of nitrogen they would have been in and the process that they would undergo as they moved (or record no change for some moves).  This information can be found by reading the text and web sources listed with the lesson.  This can be homework if class time runs short.
  6. Write a small proposal of various ways a farmer could change the amount of nitrogen in the field.  This will be homework.

Essential Files (maps, charts, pictures, or documents)

Extension Activities (how can students extend learning outside of the classroom?)

  • Have students research and write about another nutrient that plants require. Students can compare and contrast the nutrient they choose with nitrogen, including symptoms of deficiency, what the nutrient does, and where it comes from.


Part of this lesson was adapted from Windows to the Universe Teacher Resources. 


Jennifer Burn, Bedford Community High School

National Agriculture Literacy Outcomes

  • Theme 1 - Agriculture and the Environment
    • Understand the natural cycles that govern the flow of nutrients as well as the way various nutrients (organic and inorganic) move through and affect farming and natural systems
    • Evaluate the various definitions of “sustainable agriculture,” considering population growth, carbon footprint, environmental systems, land and water resources, and economics.
  • Theme 2 – Plants and Animals for Food, Fiber and Energy
    • Compare similarities and differences between organic and inorganic nutrients (i.e., fertilizer) on plant growth and development; determine how their application affects plant and animal life

Iowa Common Standards (Essential Concepts and Skills)

  • S.9-12.LS.12: Atoms and molecules cycle (e.g., carbon, nitrogen, oxygen cycles). The atoms and molecules on the earth cycle among the living and nonliving components of the biosphere.
  • HSN.Q.A.2: Define appropriate quantities for the purpose of descriptive modeling.

Next Generation Science Standards

  • HS-LS2-3 Ecosystems: Interactions, Energy, and Dynamics


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