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Science Project  
Level of Nitrogen vs. Plant Growth

Researched by Morgen A.



The purpose of my experiment was to determine the effects of water solutions that contain different levels of nitrogen on bean growth.

I became interested in this idea when I noticed my dad putting lawn clippings on our vegetable garden and I wondered if it would help the garden to be healthier and produce more vegetables.  I wondered if adding different fertilizer solutions would make a more productive garden.

The information gained from my experiment will help gardeners and farmers grow healthier gardens and more abundant crops. 


My hypothesis is that the plants receiving a 4% nitrogen solution will be affected the most by growing the tallest. 

I base my hypothesis on information that I gathered from Doug Anyan, an employee at G.S. Long.  He told me, "A plant receiving a 4% nitrogen solution would grow better than plants receiving levels of nitrogen other then 4%."

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The constants in this study were:
* the amount of water
* the amount of light
* the temperature 
* the kind of bean 
* the size of the  bean
* the size and type of container
* the location of the plants 

The manipulated variable was the amount of nitrogen in the solution.

The responding variable was the bean height in centimeters and the weight of the green matter in grams. 

To measure the responding variable I took a ruler and measured the plants in centimeters after two weeks of growth.  I then found the average of the two plant’s growth and the weight in grams of the green matter on a scale.

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20  clear containers
2 holding containers
20 bean seeds
3 jugs of distilled water
1 ruler (centimeters)
1 bag of nitrogen fertilizer 21-0-0
1 scale
7 200ml beakers
1 bag of Pearl Light
1 permanent marker (black)
7 stick on labels
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1. Gather materials
2. Fill 20 clear containers about 2/3 full of Pearl Light
3. Plant one bean seed in each container about half way down
4. Using a distilled water jug (make sure there are holes in the cap) water the beans in each container so the top is moist, but there’s no water visible on the bottom
5. Water the beans each day until 14 seeds germinate.  The other 6 are back ups
6. After 14 seeds have germinated, separate them into seven groups  of 2 each
7. Label 2 containers 1/2% nitrogen
8. Repeat step #7 with the other containers, except label each group of two 1%, 2%, 4%, 6%, and 10%
9. Pour 200 ml of distilled water into each of the seven beakers
10. Us a balance scale to weigh the nitrogen from the bag.  Add the nitrogen to the scale until it balances at 0.  Set the scale to 1 gram for 1/2%, 2 grams for 1%, 4 grams for 2%, 8 grams for 4%, 12 grams for 6%, and 20 grams for 10%. 
11. Pour the nitrogen into the beaker labeled 1/2% nitrogen.
12. Repeat steps 10 and 11 five more times, except set the scale so that it will balance for the different levels of nitrogen.
13. Shake each container vigorously until the nitrogen dissolves
14. Using a 1 ounce measuring cup, fill it with the 1/2% nitrogen solution about 2/3 of an ounce full
15. Pour the solution into one of the containers labeled 1/2%
16. Repeat step #15 with the other solutions.  Have one beaker contain just distilled water.  That is the water for the "Control Group."
17. Let the containers sit on a windowsill or under a grow light.
18. Water the beans every other day during a two-week growing period.  If you need to make more of one of the nitrogen solutions, follow steps #9-#13
19.  After the two weeks are up, carefully remove the plants from the Pearl Light but measure the plants before taking them out.
20. Record the height (in centimeters) and the weight (in grams) of the plants and find the average for each group.

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The original purpose of this experiment was to determine if the level of nitrogen would affect a plants growth. 

The results of the experiment were the control group grew the best (20cm), the .5% and the 1% grew the second best (1.5cm), and the 2%, 4%, 6%, and the 10% died.  The control group also weighed the most (3.5g), the 1% was the second heaviest (3g), the 2%, 6%, and the 10% weighed 2g, and the .5% and the 4% weighed 1.5g.

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My hypothesis was that the plants receiving a 4% nitrogen solution would grow the best.

The results indicate that this hypothesis should be rejected.  My results indicate that the plants that weren’t given any nitrogen (the control group) grew the best.

Because of the results of this experiment, I wonder if a plant receiving an amount of nitrogen larger then 2% will die and if I would get the same results if I used different plants?

The usefulness of my findings will benefit farmers so they know not to overdose their bean plants with nitrogen. 

If I were to conduct this project again I would try harder to find more info before writing my procedures, I would start growing my plants in early November for better results, I would use more plants in each of my groups, and I would try to get better pictures to document by experiment.

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 Beans are important sources of food.  Certain beans are among the most nourishing vegetables human beings eat.  Nitrogen, along with other important elements, help to make a plant grow so that animals and humans can have food and oxygen. 


 A bean is the name of several plants that belong to the pea family.  They are one of the most nourishing vegetables that humans eat.  Beans also have the power to enrich soil.  These are some of the reasons why beans are among the most important vegetables grown by farmers today.  There are insects that are a threat to the bean.  Mexican Bean Beetles, Aphids, and Leafhoppers are considered to be the bean's worst enemies.

Types of Beans

 There are two major types of beans.  There are beans that grow low to the ground and are considered bushy and there are types that climb around poles of other plants.  Other varieties are snap beans, which are eaten as immature pods.  Types of snap beans include string, stringless, and wax beans.  Dry beans are used when they're in their mature dry form.  Pinto, Navy, Great Northern, Kidney, and Pink beans are types of dry beans.  Green Shell beans are eaten at their full size.

How Beans Grow

 Beans need sun, water, and soil to grow.  A bean is divided into two halves lengthwise.  When the bean seed is ripe, the plant splits the two halves open and the plant starts to grow up through the soil.  When certain beans reach the level of growth at which they are used or eaten they are picked.


 Plants are essential to human and animal survival.  They provide us with oxygen to breathe and we give them carbon dioxide.  Scientist's know of 260,000 species of plants on our earth.  Plants provide us with types of food, clothing, paper, fuels, plastics, etc.  In order for a plant to grow it needs proper temperature, moisture, and oxygen.  After germination, a plant needs sunlight, water, and soil.


 Nitrogen is a colorless, tasteless, odorless element.  It constitutes about 78% of the earth's atmosphere by volume.  Nitrogen doesn't exist in the soil in a natural mineral form.  The scientific symbol for nitrogen is N.  The amount of nitrogen a plant is receiving affects its growth.

Nitrogen Cycle

 In order for nitrogen to help a plant grow it has to go through a cycle known as the nitrogen cycle.  The first step is called nitrogen fixation.  In this step the nitrogen is converted into compounds the plant can use.  During the second step the plant uses the nitrogen compounds and makes them into protein.  The third step consists of animals eating the plants and the proteins in the plant.  During the fourth and final step dead animals and plants return nitrogen to the soil and nitrogen gases into the air. 


 Fertilizers are used to increase the level of certain nutrients in the soil.  Ancient farmers would use manure or guano for fertilizers.  Industrial waste is in some commercial fertilizers.  An overuse of fertilizer can be harmful to the plant or plants it's being used on.

Types of Fertilizers

 Types of fertilizers include compost and mulch.  Compost is made up of partly decayed plant materials.  Mulch is any material that's spread over the soil in order to let air in and reduce the amount of water that evaporates from the soil.  Mulch can be straw, hay, clover, chaff, alfalfa, leaves, and other substances.  It should be applied about 2-3 inches thick.  Mulch also reduces weed growth, but it costs more than commercial fertilizers.

How Nitrogen Fertilizers Are Made

  Manufactures that make fertilizers with nitrogen in them have to go through a process in order to get it.  First, the manufactures separate the nitrogen from the oxygen by a process called distillation.  According to World Book Encyclopedia, "Distillation is a process that separates a mixture by using vaporization."  The nitrogen is then collected in special containers and stored under great pressure. 


  Beans are some of the most important vegetables that are grown by farmers today.  Beans and other plants use nitrogen.  Nitrogen has to go through the nitrogen cycle so that it can help the plants grow.  Fertilizers are used to promote plant growth, but an overuse can be harmful to plants.  There are different types of fertilizers including mulch and compost.  Fertilizer manufactures have to go through a process to get nitrogen for their fertilizers.  These are some basic facts about beans, fertilizers, and nitrogen.

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Acker, Duane. "Agriculture," World Book Encyclopedia. 1995. Pp. 146

AIL Agricultural Laboratories. Agronomy Handbook, A and L Laboratories: AIL Laboratories, Unknown

Butt, John B. "Distillation," World Book Encyclopedia. 1995. Pp. 238

Edwin, Munson S. "Nitrogen," World Book Encyclopedia. 1991. Pp. 429 and 430

"Fertilizer," Encarta Encyclopedia. 1999.

Gibson, Sullivan J. and Bratten, James W. Soils, University of Alabama: University of Alabama, 1970.  Pp. 279

Hershey, David R. Plant Biology Science Projects. Canada: John Wiley and Sons Inc., 1995. Pp. 3, 4, 7, 9, 10, 11, 12, 14, 17

Howell, Catherine Herbert. "Plants," Washington D.C., National Geographical Society: 1998.  Pp. 8

McKenzie, Paul G. "All About Fertilizers,", Unknown

"Plant," World Book Encyclopedia. 1991. Pp. 516, 536, 537

Salunkhe, D.K. and Kadam, S.S.  Bean, Academic American Encyclopedia. Unknown. Pp.  139

Siegchrist, Charles. "Fertilizers for Free, United States of America, A Story Publishing Bulletin," 1980.  Pp. 1, 9, 10, 11, 21

Taylor, Johnston J. "Compost," World Book Encyclopedia. 1999. Pp.  906

Taylor, Johnston J. "Mulch," World Book Encyclopedia. 1991. Pp. 913

Weier, Elliot T., Stocking, Ralph C., and Barbour, Michael. Botany an Introduction to Plant Biology. United States of America: John Wiley and Sons Inc., 1974

Wittwer, S.H.  "Bean," World Book Encyclopedia. 1995. Pp.  180-182

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