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Growing, Growing, Gone! An Experiment on Nitrogen Fertilizers

Difficulty
Time Required Long (2-4 weeks)
Prerequisites None
Material Availability Readily available
Cost Very Low (under $20)
Safety Adult supervision recommended during preparation of nitrogen fertilizer solution

Abstract

Plants need nitrogen to build proteins and nucleic acids to grow healthy stems and leaves. Though the Earth's atmosphere is made up of 79% nitrogen, the form of nitrogen found in the atmosphere cannot be used by plants. In this experiment, you will compare plants grown without nitrogen fertilizer to plants grown with nitrogen fertilizer.

Objective

The goal of this experiment is to compare the growth of plants with and without added nitrogen fertilizer.

Credits

La Né Powers
Edited by Andrew Olson, Science Buddies

Cite This Page

MLA Style

Science Buddies Staff. "Growing, Growing, Gone! An Experiment on Nitrogen Fertilizers" Science Buddies. Science Buddies, 26 June 2014. Web. 30 Aug. 2014 <http://www.sciencebuddies.org/science-fair-projects/project_ideas/PlantBio_p012.shtml>

APA Style

Science Buddies Staff. (2014, June 26). Growing, Growing, Gone! An Experiment on Nitrogen Fertilizers. Retrieved August 30, 2014 from http://www.sciencebuddies.org/science-fair-projects/project_ideas/PlantBio_p012.shtml

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Last edit date: 2014-06-26

Introduction

Plants require more than just water and sunlight to grow. They also require many nutrients found in the soil. One of the most important nutrients required for plant growth is nitrogen. Nitrogen is used to build plant proteins and nucleic acids, including DNA.

Nitrogen is found naturally in the atmosphere and in the soil. Even though there is an abundance of nitrogen available, the most common form of nitrogen (N2) cannot be used by plants. Nitrogen can be combined chemically with oxygen or hydrogen to form types of nitrogen compounds that plants can use. These nitrogen compounds can be added to the soil in the form of ammonium (NH2+) and nitrate (NO3+) fertilizers. Plants grow well when fertilizer containing nitrogen is added to the soil, but this method can be expensive and has to be repeated each time the nitrogen in the soil is used up.

In this experiment, you will compare plants grown without nitrogen fertilizer to plants grown with nitrogen fertilizer. You will observe the effects of nitrogen on the health of the plants by measuring the increase in biomass of each plant during the experiment.

Terms and Concepts

  • fertilizer
  • nutrient
Questions
  • What nutrients do plants need to survive?
  • How do plants use nitrogen and what do they use nitrogen for?

Bibliography

Materials and Equipment

Note: Adult supervision recommended during preparation of nitrogen fertilizer solution.
  • at least eight small pots
  • potting soil
  • one packet of seeds
  • commercial nitrogen fertilizer mix for house plants (e.g., Miracle Gro, Peter's or equivalent)
  • empty glass or plastic bottle for mixing nitrogen fertilizer

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Experimental Procedure

Note: Adult supervision required during use of nitrogen fertilizer.
  1. Make sure pots have holes in the bottom to allow the roots to "breathe" and excess water to drain out.
  2. Measure equal amounts of soil into each of the pots.
  3. Moisten the soil in each pot with the equal amounts of water.
  4. Label four pots with "nitrogen fertilizer" and four pots with "no nitrogen added."
  5. Plant seeds in each pot according to seed packet instructions.
  6. Place plants near a sunny window or under a grow light.
  7. Check your plants regularly and water when needed.
    1. Soil should be kept moist.
    2. Water the "no nitrogen added" pots with regular water.
    3. Water the "nitrogen fertilizer" pots with water mixed with nitrogen fertilizer. Follow the fertilizer manufacturer's recommendations for preparing this solution.
    4. All plants should receive the same amount of liquid at each watering.
    5. Keep track of your watering schedule in your lab notebook.
  8. At regular intervals, record observations on the growth of the plants (e.g., height, number of leaves on each plant, etc.) in your lab notebook. For information on scientifically measuring plant growth see the Science Buddies How-to page, Measuring Plant Growth.
  9. Here is a sample data table for organizing your data:

    No Fertilizer With Fertilizer
    #1 #2 #3 #4 #5 #6 #7 #8
    Date:
    • Height
    • # of Leaves
    • Observations
                                                                                                                                   
    Date:
    • Height
    • # of Leaves
    • Observations
                                                                                                                                   
    Date:
    • Height
    • # of Leaves
    • Observations
                                                                                                                                   
    Etc.




                                                                                                                                   


  10. Allow plants to grow to maturity, then make final measurements of the growth of each plant. Here are some suggested methods for accurately quantifying plant growth: http://sciencebuddies.org/science-fair-projects/project_ideas/PlantBio_measuring_growth.shtml.
  11. Summarize your results by averaging over the No Fertilizer and + Fertilizer Conditions, and prepare one or more bar graphs to compare your measurements.

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Variations

  • Compare different amounts of nitrogen fertilizer to see what the ideal concentration is for growing plants
  • Experiment with other types of nutrient fertilizers to test their effects on plants.

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