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The Effect of Different Detergents on Pea Growth.

Researched by Katie K.


The purpose of this experiment was to see how detergent affects the growth of bush peas.

I became interested in this idea when my mom accidentally watered the plants with soapy water. The plants died, but it was late in the fall, so I wasn’t sure if the soapy water caused them to die.  

The information gained from this experiment could help farmers and gardeners understand how soapy wastewater affects their crops. It would also be useful to industries that produce or use large amounts of detergent or soap.  




My hypothesis was that the plants receiving detergent would grow more poorly.  

I based my hypothesis on World Book Encyclopedia 2002 which said that detergent has a lot of chemicals, so I think that will harm the plants.

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The constants in this study were:
* Number of seeds put in each pot
* The temperature they grow in
* The type of seeds used
* How old the seeds are and how they are stored
* Type of soil 
* The soil’s moisture
* The amount of light the plants get
* Pot size and shape
* The amount of soil
* Planting depth
* Testing procedures
* How tall the peas are before detergent is applied
* The amount of water
* Type of detergent within a specific test group.

The manipulated variable was the type of detergent put into the pea plant’s water 

The responding variable was the mass of the peas when they have completed their growth.  

To measure the responding variable I weighed my pea plants with a triple beam balance.

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4 Pea Packets
30 Foil Trays
30 Pots
1 Growing Tent
1 Florescent Light
1 Triple Beam Balance Scale
1 40 milliliter cup
1 Box of powder detergent no bleach
1 Box of liquid detergent with no bleach
1 Bag of soil
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1. Make five holes in 15 of the foil trays one in each corner and one in the center.
* Put 4 sticks in foil trays that don’t have the holes.
* Set each tray with holes into sticks in tray without holes.
2. Fill all 30 pots with soil leaving about 3 centimeter on the top.
3. Plant three pea seeds 2 cm deep in all 30 pots.
4. Water each of the pots 40 ml every 5 days.
5. Put all the pots in the growing tent and turn on the light for 10 hours.
6. Turn off the light for the remainder of the day.
7. Repeat steps 4-6 everyday until the peas are at least one centimeter tall.
8. Mix 1ml of powder detergent into 40 ml of water before water before watering 10 of the plants.
9. Mix 1ml of liquid detergent into 40ml in 10 different plants.  
10. Continue watering the control group with no detergent.
11. Repeat steps 8-10 everyday you water them add the detergent to their regular water.
12. Repeat step 10 for 3 weeks.
13. After the third week of watering the plants pull them out roots and all and dry them off and then weigh them with a triple beam balance.
14. Record data.  

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The original purpose of this experiment was to see how detergent affects the growth of peas.

The results of the experiment were the liquid detergent grew more than water and powder detergent.  

See my Data Table and Graph.

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My hypothesis was that the plants receiving more detergent would grow more poorly.

The results indicate that this hypothesis should be rejected because the plants that got liquid detergent grew better.

Because of the results of this experiment, I wonder if different amounts of detergent would affect them differently. Would different sorts of pollution like acid or anti freeze change the results a lot.

If I were to conduct this project again I would have more plants in each group. I would add a smaller amount of detergent perhaps 1 ml per 100ml. I would try to test something more important to the world like corn or wheat.  

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Humans need food. Agriculture produces most of our food efficiently. Pollution damages plants including food. Detergent is a type of a pollution.


Peas have been around since the cave men and still popularly used through out the world. They are in the legume family. Legumes are important because they can take nitrogen from the air and use it to grow. There are about 12,000 to 14,000 different plants in the legume family. Like broom, peas, peanuts, beans, and clover are a few examples that are in the legume family. Peas have vitamin C and A in them. All peas are cultivated and two main peas are garden peas and field peas. Garden peas you can eat and field peas are mainly used to feed livestock.  


Germination is the sprouting of a seed. A seed is made up of a seed coat, embryo, and endosperm. The endosperm is the food storage tissue in the seed. The seed coat is the hard layer around the outside of the seed. The embryo is the part of the seed that actually becomes the plant. The part that becomes the roots is called the hypocotyls and the part that becomes the stem and leaves is called epicotyls.

Dormant seeds take weeks to months just to germinate. Two things that can cause seeds to break dormancy is a certain amount of sunlight or a certain amount of cold weather. Dormancy is good for plants because it can stop the seeds from germinating too soon when growing conditions are not favorable.

Seeds often become dehydrated during dormancy and need water to begin germination. Like when people get dehydrated and they need water to survive.


Photosynthesis is a process used by plants, which takes two things carbon dioxide and water, which makes useable sugars for plants to grow. This process also uses a substance called chlorophyll. Carbon dioxide gets into the stomata, which are small openings in the underside of the leaf. Chlorophyll is a green pigment that makes the leaves green. Water gets into the plant by going through the roots, up the stem and to the leaves. This process also requires sunlight. It can be written as the following equation.

6 H2O + 6 CO2= C6H 12 O6 + 6O2 


Agriculture involves growing food to feed livestock and people. Over half the world’s employee work in agriculture. Agriculture was developed about 10,000 years ago. People used to get food from bushes or catching fish. There are eight major groups in agriculture, (1) grains, (2) roots, (3) pales, (4) fruits and vegetables, (5) oil-bearing, (6) sugar-bearings, (7) nuts, (8) coca beans. Farmlands cover over half of the United Sates. The rest is used to raise livestock. Only two percent of all working Americans are farmers that work on a farm. Yet still the United States has much of the world’s food.


Detergent has been around since the 1940’s and still is commonly used to clean your household. It is often used in the laundry to clean clothes. All detergents contain a surfactant which is a chemically reacts to messy substance like a hand grabbing dirt. Some detergents have different surfactants; some even have perfume and color added to them.

Detergent is used everywhere around the house it is used to clean dishes, candle wax, blood, and all most anything else.   ]


Every body in the world needs food and agriculture produces most of the worlds food. Pollution damages plants including food. Detergent is a type of pollution.

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 “Detergent and soap”. “ World Book”, 5 2002 

“Detergent. ” ENCARTA Encyclopedia Deluxe. 2001 edition. CD-ROM. Redmond, WA: Microsoft Corporation, 2001.

“Detergent and Soap”. Feinstein, Myron. E “ The World Book Multimedia Encyclopedia,”

“ Detergent”. “ Science Encyclopedia,” 6 1997

“Ingredients. ” ENCARTA Encyclopedia Deluxe. 2001 edition. CD-ROM. Redmond, WA: Microsoft Corporation, 2001.

“Peas. ” “ENCARTA Encyclopedia Deluxe. 2001 edition. CD-ROM. Redmond, WA: Microsoft Corporation, 2001.

“Photosynthesis” January 14, 2004<http://www. alienexplorer. com/ecology/e66.html

“Soap. ” ENCARTA Encyclopedia Deluxe. 2001 edition. CD-ROM. Redmond, WA: Microsoft Corporation, 2001.

“Soap and Detergent. ” ENCARTA Encyclopedia Deluxe. 2001 edition. CD-ROM. Redmond, WA: Microsoft Corporation, 2001.

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I would like to thank the following people for helping make my project possible:
* My parents for helping set up my experiment and growing tent.
* Mr. Newkirk for fixing my report and loaning me things to make my experiment work correctly.  
* Mrs. Helms for helping me format my graphs and helping get stuff for my experiment.


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