The Effect of Potable vs. Gray Water on Radish Growth

Researched by Myca T.
2001-02

PURPOSE

The purpose of this experiment was to determine if radishes irrigated with gray water rather than potable water have greater biomass. 

I became interested in this idea while watering plants at my house. I wondered why people always used "good" water to irrigate plants rather than recycled water. 

The information gained from this experiment may be used to help conserve water and enhance plant growth.

HYPOTHESIS

My hypothesis is that radishes irrigated with gray water will have greater biomass in a period of 42 days vs. radishes irrigated with potable water over the same period of time. 

I base my hypothesis on the fact that gray water contains small particles of compost material which could act as a fertilizer. 

EXPERIMENT DESIGN

The constants in this study were:
* The type of radish
* The pot size (one gallon)
* The type of soil (Miracle-Grow)
* The amount of water added to each plant (350ml)
* The temperature of the water added to each plant (room temperature)
* The amount of light each plant was exposed to (8-9 hours)
* The temperature of which each plant was grown (60°-80°)
* Date of planting (12/9/01) 
* Date of harvest (1/20/02)
* Method of judging biomass (triple beam balance)
* Period of time before sunlight rotation (one week)
* Method of planting (See procedures) 
* Depth of seed planting (13mm)
* Method of rinsing off plant (See procedures)
* Method of drying off plant (See procedures)
* Temperature of rinsing water (See procedures)
* Amount of radish seeds in each pot (four)
* Amount of potting soil in each pot  (1,100 grams)
* Where each seed is placed (in 90° intervals)

The manipulated variable was the type of water added to each of the experimental groups. There were two experimental groups. Each group received a different type of water. 

The responding variable was the biomass of the radish. 

To measure the responding variable the mass of the entire radish plant was measured in grams, after a period of 42 days. 


MATERIALS
 
QUANTITY  ITEM DESCRIPTION
24 radish seeds
6 2 liter plastic planting containers
6,600 grams potting soil
350ml each watering potable water
350ml each watering  gray water
1 growing table
6 drainage dishes
1 light source
1   triple beam balance
1 25ml graduated cylinder
1 potting soil scoop
1 ruler
2 new water containers
1 sink
6 paper towels
1 permanent marker

 PROCEDURES

1. Gather materials
2. Prepare gray water (at least 12 hrs. before planting) Gray water will be prepared by dumping 1 liter of used dish water into a bucket. Set for at least 12 hrs. Potable water will be prepared in the same way and at the same time. Except water will come from spigot of the sink.
3. Label containers "gray water" 1-3 and "potable water" 1-3
4. Place 1,100 grams of potting soil in each container
5. Shake container side to side 3 times so soil is spread evenly
6. Tap container on table 3 times so soil is packed down
7. Make a mark 13 mm from top of finger
8. At every 90° interval around container measure in 7.5cm and plunge finger into soil until  mark on finger is level with soil
9. Place one radish seed on bottom of each hole
10. Put soil back over seed
11. Add 350ml of gray and potable water to respective plants
12. Repeat step 11 as needed keeping amount of water constant for all plants
13. Rotate plants one to the left each week to ensure plants receive equal amount of sunlight
14. On the 42nd day gently uproot gray water plants and leave lying in container 
15. Repeat previous step with potable plants
16. Fill container with room temperature water 
17. Dip each plant into 350ml of water 15 times with the same force and temperature. This is to get any excess dirt of the plant roots and fruit. 
18. Lay on paper towel to dry for 10 min. Keeping plant groups separate at all times. Turn plant over at 5min. interval
19. Weigh entire biomass of each of the 12 gray water plants
20. Repeat previous step with potable plants
21. Average the biomass of the gray water plants
22. Repeat previous step with potable water plants
23. Draw conclusion(s) 

RESULTS

The original purpose of this experiment was to determine weather radishes irrigated with gray water rather than potable water have greater biomass. The results of the experiment were that radishes watered with gray water did not have a greater boimass. Instead plants that were watered with potable water grew an insignificant amount more.  Potable water averaged to be about .17 grams heavier than the radishes that were irrigated with gray water. I think this occurred because mold from the food particles, started growing on the plant, and this may have caused some damage in the growth.  The final averages were very close.
View my data and graphs

CONCLUSION

My hypothesis was that radishes irrigated with gray water would have greater biomass than radishes that are watered with potable water. The results indicate that this hypothesis should be rejected. Radishes watered with gray water and potable water weighed about the same over all. Therefore I would still advise strongly using gray water to irrigate radishes, because it causes no harm, and works nearly as well as potable water. 

These findings could be useful to people who wish to conserve water, showing them that it does not make a difference in which kind of water they use to water plants. 

 Because of the results of this experiment, I wonder if radishes watered with bath water instead of sink water would grow any better. I also wonder why sometimes radishes are so big, and other times so small. If I were to conduct this project again I would have allowed the radishes to grow six more weeks to ensure that they were fully grown. I would also have grown more plants so that, I could have more radishes weights to average, and my results would be more reliable. 


 

RESEARCH REPORT

Introduction

Recently the Pacific Northwest has experienced drought conditions.  This experiment was designed to create a way to conserve water in an economical and practical way by watering green plants with recycled water.  In this research report, topics will be discussed that are essential in this experiment.

Water

Water is made of hydrogen and oxygen.  Its chemical formula is H20.  Each day an average person uses more than 100 gallons of water.  A person will take in about 16,000 gallons of water in a lifetime.  The world is facing the prospect of water shortages because of population growth, uneven supplies of water, pollution, and other factors.  The United Nations predicts water shortages could retard the economic growth of some countries, lead to food shortages, and possibly bring international conflicts.  Based on these important facts, people living today need to concentrate on how to conserve water.

The total amount of water on the earth is 326 million cubic miles.  Salt water makes up 97% of the world’s surface water.  Salt water is unfit for human consumption.  Only 3% of the earth’s water is fresh.  Of this fresh water, three-fourths is frozen in glaciers and ice caps. 

Water problems occur in the United States because water has appeared to be been plentiful, easy to get, and cheap.  People have become careless and wasteful.  In the past, people have dumped untreated sewage and other waste into fresh water resources.  As a  result, water has been spoiled.  There have been many attempts to increase the amount of our fresh water supply.  For example, people have sprayed the clouds with chemicals to make them release more moisture.  Scientist have developed a way to change salt water to drinking water, however, this process is very costly. 

Water is never actually used up.  It is simply reused in the water cycle.  For this reason, efforts should be made to recycle water and not contaminate it. 

Gray Water and Potable Water

Gray water is any kind of  used water from the home except toilet water.  At times, gray water can be used in place of drinking water so that drinking water is not wasted.  An example of this is watering grass and plants.  Gray water may contain small bits of plant and animal matter and detergents.  These particles can act as compost or fertilizers that are helpful for plant growth.  Having households use gray water for indoor or outdoor watering purposes may put less strain on septic tanks and water treatment plants.

Potable water is water that is suitable for human consumption.  This water may come from an underground aquifer or from some other domestic water supply.  This water is commonly known as "household" water.  This water is used to wash clothes and dishes, drink and bathe in, fill hot water tanks and toilet bowls, and is often used to water yards, flower or vegetable gardens.  Potable water is used and then drained into septic tanks or sent to water treatment plants.

Radishes

Radishes are a type of root plant like carrots, beets, sweet potatoes, yams, and potatoes.  They have a tap root system.  A taproot is a main root that grows straight down. Radishes belong to the mustard family and their scientific name is Raphanus sativus.  Radishes are crisp and sharp tasting.  They are eaten in salads or as appetizers.  Some different types of radishes are French Breakfast, Cherry Belle, Scarlet Globe, and White Icicle.  Radishes can either be round, oblong or shaped like icicles.  They range in weight from 
28 grams to one kilogram.  Their colors are various: white, red, yellow, pink, purple, black, and a combination of red and white.  Radishes grow best in cool weather and are able to withstand frost.  They have a growing period of twenty to sixty days.  They are harvested in the United States in March, April, and May.  In Florida, California, and Ohio, they grow year-round.

Plants

There are 260 thousand types of plants that grow on mountaintops, in oceans, in deserts, and in snow-covered areas.  They range in size from big to small.  Plants produce oxygen which helps us breath.  They also provide food for the world’s population. 

There are four parts of a plant: the roots, the stem, the leaves, and the flower.  Roots grow underground and absorb water and minerals.  They also hold the plant in place.  Stems support the leaves and flowers.  They also hold leaves up toward the sunlight.  Leaves make most of the food the plant needs.  Flowers are where seeds grow.

Plants are identified by their leaves, stems, roots, life spans, and reproduction cycles.  All seed producing plants and ferns are vascular.  Stems and roots of these plants have vascular tissues, which are have tubes or some way of transporting needed materials to a plant.  There are two different types of vascular tissues.  Xylem is a tissue that carries nutrients up from the roots.  Xylem cell walls are thick and help support the plant.  Phloem tissues carry water, nutrients, and waste throughout all the plant.  Phloem carry materials up and down the plant; xylem carries it just up.

Germination

Germination is the sprouting of a seed.  Most seeds have periods of dormancy before growing.  For a plant to grow properly, it needs the proper temperature, moisture, and oxygen. .  Plants grow best in the temperatures between 18.3 C° and 29.4 C°  A plant will germinate at time that suits its climate.  Seeds get moisture from the ground where it is planted.  This moisture softens the seed coat and growing parts break through.  As the seed splits, a tiny seedling appears.  The lower part of the seedling turns into root and the upper part of the root grows up.  The tip of the seedling will be the bud that produces leaves.  Moisture provides nutrients to the plant and the plant continues to grow.  Too much water rots the plant.  Yet, not enough water will slow down or end the growing process.  Oxygen is needed so changes can take place within the plant.  A plant’s growth is determined by its heredity and environment.  Heredity determines the characteristics of the plant.  The environment is the plant’s living conditions. 

Photosynthesis

Photosynthesis is the process plants use to make food from carbon dioxide gas, water, and energy from sunlight.  Light energy is converted into chemical energy which helps produce food for the plant.

Light is absorbed by a green pigment called chlorophyll.  Chlorophyll is a pigment that makes the plant appear green.  Each food-making cell in a plant has chlorophyll in it.  Chlorophyll is in small bodies in the plant cell called chloroplasts.  In chloroplasts, the light energy that was absorbed divides that water drawn from the soil into two different molecule parts, oxygen and hydrogen.  In a series of complicated steps, hydrogen mixes with carbon dioxide from the air to form a simple sugar.  The oxygen from the water is given off in the process.  From the sugar and other ingredients in the soil, a plant is able to create the nutrients it needs to live. The oxygen green plants produce is essential for human life.

Soil

Most plants are grown in some type of soil.  Commercial potting soil can be used.  Potting soil is formulated from forest products, Canadian sphagnum peat moss, horticultural perlite, a wetting agent, and fertilizer.  Other ingredients found in potting soil are nitrogen (a gas), phosphate (an acid), and potash (a type of potassium).

Detergents

A detergent is a substance that cleans a soiled surface.  Soap is a type of detergent.  Detergents are produced as bars, flakes, grains, liquids and tablets.  People use detergents to wash dishes, laundry, floors, windows and other household items.  Doctors even use detergents to kill germs.  These cleaners contain a basic cleaning agent called surfactants or surface-active agent.  Surfactants attach themselves to dirty particles then pull out dirty particles and store them until the soap and dirty particles are washed away.  Most detergents contain a man-made product plus other chemicals.  These other chemicals may improve cleaning ability or make the product easier to use.  Soaps and detergents often have added colors or perfumes.  Most surfactants used today are biodegradable. 

Recycling

Recycling is a process designed to collect, process, remanufacture, and reuse materials instead of disposing of them.  Recycling also helps conserve raw materials and energy that manufacturers would otherwise use to make new products.  Pollution can also be reduced when recycling occurs. 
 

BIBLIOGRAPHY

Dimichele, William A. "Plants" The World Book Encyclopedia 1999 vol. 15 pages 536-537

Feinstein, Myron E.  "Detergent and Soap" The World Book Encyclopedia 1999 vol. 5 pages 163-166

Gedzelman, Stanley David. "Air" The World Book Encyclopedia 1999 vol. 1 page 166

"Gray water Central" www.graywater.com 9/10/99

Hughes, George R. "Radishes" The World Book Encyclopedia 1999 vol. 16 pages 99-100

Keinath, Thomas M. "Water" The World Book Encyclopedia 1999 vol. 21 page 116

Kyle, William C.  Jr. , Rubinstein , Joseph H. and Vega, Caroline J. " Real Science." Columbus, Ohio McGraw- Hill Companies 2000

"Miracle Grow" 2/10/02 http://www.scotts.com/gardening/ContainerSoils.cfm 

"Plant." Student Discovery Encyclopedia  2000 vol. 9 pages 94-95

"Recycling." World Book Encyclopedia 1999 vol. 16 pages 184 and 185

"Root." Student Discovery Encyclopedia 2000 vol. 9 page 242

Tesar, Jenny. "Food and Water: Threats, Shortages, and Solutions." New York, NY A Blackbirch Graphics Inc. 1992 pages 63-91

Turner, Steve. "Will There be Enough Water in the Next Century?" Microsoft Encarta Encyclopedia 2001

Wagner, David H.  "Photosynthesis." The World Book Encyclopedia 1996 vol. 15 page 430
 
 

 

ACKNOWLEDGEMENTS

This science project would not have been possible without the help of my parents, My sister, and Mr. Newkirk. My parents gave me ideas for my science project, helped me correct my reports, showed me how to border documents on my board properly, and helped me buy the materials necessary to complete the procedures in this experiment. My little sister had done a science experiment before and showed me how to correctly set up my board.  Mr. Newkirk also helped critique my reports and showed me the proper methods of completing a science project.

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