The purpose of
this experiment was to compare the effect of four common types of domestic
water on the growth of soybeans: chlorinated municipal water, un-softened well water,
potassium salt softened water, and sodium salt softened water.
I became interested in this idea because every summer I helped my mom water our plants. She always told me not to water them with our softened, chlorinated water. I often wondered what would happen.
The information gained from this experiment could be very useful to gardeners and farmers who irrigate with domestic water. It would help them decide which type of water to use (or avoid) to help their plants grow best.
My first
hypothesis was that the potassium salt softened water would result in the most
plant growth in mass.
My second hypothesis was that the potassium salt softened water would result in the most plant growth in height.
My third hypothesis was that the sodium salt softened water would result in the least plant growth in mass.
My fourth hypothesis was that the sodium salt softened water would result in the least plant growth in height.
My fifth hypothesis was that the un-softened well water would result in less soybean growth in mass than potassium salt softened water, but more than the chlorinated water.
My sixth hypothesis was that the un-softened well water would result in less soybean growth in height than potassium salt softened water, but more than the chlorinated water.
I based my first and second hypotheses on information I collected from the Morton Salt website. The website stated, “Potassium is one of the 16 elements necessary for plant growth. It also helps plants resist disease and optimize moisture utilization.”
I based my third and fourth hypotheses on information I found from Penn State College of Agricultural Sciences. In their website they stated, “Calcium and magnesium compounds are the components that make water hard. They are important nutrients for plants and sodium is not. Softened water can also affect the soil structure for a potted plant.”
I based my fifth and sixth hypotheses on information I found at a website created by Penn State College of Agricultural Sciences. They stated, “If there is a source of un-softened water, use that water for your plants. If you have a faucet in your water line before the water softener, you can also use that tap as the source of un-softened water for your plants.”
The constants in this study were:
• Date planted
• Depth planted in the soil
• Amount of water given to plants at any one time
• Amount of soil in each planting cup (1/4 of a cup)
• Type of soil
• 16 hours of light for all plants
• Distance of light above soil
The manipulated variable was the type of water used on the soybeans.
The responding variables were height and mass of the soybeans.
To measure the responding variables I used a centimeter ruler to determine height and a triple beam balance to measure biomass.
QUANTITY
|
ITEM DESCRIPTION
|
1
|
3cc. Syringe
|
2
|
Planting
trays with 72 individual soil cells
|
1
|
Bag of
potting soil
|
1
|
Automatic
Timer Switch
|
4 Liters
|
Well water (un-softened)
|
4
|
Plastic
Containers for the four types of water
|
4
Liters
|
Potassium
salt softened water
|
4
Liters
|
Sodium salt
softened water
|
4
Liters
|
Chlorinated
water (un-softened)
|
1
|
Triple Beam
Balance
|
1.
Fill all 72 individual cells in a divided planting tray with potting
soil.
2. Repeat step 1 using another tray. So you should have 2 trays altogether
3. Plant one soybean one centimeter deep in the soil in each cell.
4. Divide the plant holders into four groups of 36.
5. Make labels (Sodium, Potassium, Chlorinated, and Un-softened well water) one for each of the four sections.
6. Water the soybeans with the 3cc syringe but water them with 5cc of water. Use only the type of water for that group.
7. Put the transparent cover on top of the plant holders to act as a mini green house.
8. Every day, leave the lights on for 16 hours.
9. After 16 hours of light turn off the lights for 8 hours.
10. Look at the temperature in the room and record it in a journal.
11. Once the sprouts have grown so big that they touch the plastic covers, remove the covers.
12. Repeat step 5, except this time instead of using 5cc of water use 3cc.
13. If there are any sprouts, count them and record the amount.
14.
Repeat steps 6-14 until the experiment is complete.
15. Once the experiment is finished, uproot each plant one section at a time.
16. Rinse off the plant roots until there is no dirt on them.
17. After all the dirt has been removed, measure the height of each plant
with a tape
measure. Make sure to measure in centimeters.
18. Record the heights. Add up all the measurements and divide the total by how many plants there are to get an average height. Round to 1 decimal place.
19. Now, place one of the four groups on a triple beam balance to find the biomass of the watering group.
20. Divide the total weight (in grams) for the group by how many plants there are in the group. That will be the average. Round to 2 decimal places.
21. Repeat 19-20 with each of the 3 remaining groups.
The original
purpose of this experiment was to compare the effect of four common types of
domestic water on the growth of soybeans: chlorinated municipal water,
un-softened well water, potassium salt softened water, and sodium salt softened
water.
The results of the experiment were that the sodium salt soybeans grew the most plants. But the potassium salt soybeans had the greatest average in growth. The un-softened well water soybeans resulted in the least plant growth. The potassium soybean group weighed the most and the chlorinated water weighed the least.
My first
hypothesis was that the potassium salt softened water would result in the most
plant growth in mass.
The results indicate that this hypothesis should be accepted, because potassium water did result in the most plant growth in mass.
My second hypothesis was that the potassium salt softened water would result in the most plant growth in height.
This hypothesis should be rejected, because it turned out that un-softened well water resulted with the most plant growth in height. Potassium salt softened watered soybeans had the second to the most soybean plants.
My third hypothesis was that the sodium salt softened water would result in the least plant growth in mass.
This hypothesis should be rejected, because the sodium softened watered soybeans had the second to the most mass.
My fourth hypothesis was that the sodium salt softened water would result in the least plant growth in height.
This hypothesis should be rejected, because sodium salt softened water had the second to the least average of heights.
My fifth hypothesis was that the un-softened well water would result in less soybean growth in mass than potassium salt softened water, but more than the chlorinated water.
This hypothesis should be accepted, because un-softened well water was less then potassium and more then chlorinated water.
My sixth hypothesis was that the un-softened well water would result in less soybean growth in height than potassium salt softened water, but more than the chlorinated water.
This hypothesis should be rejected, because un-softened well water resulted in the most plant growth in height.
After thinking about the results of this experiment, I wonder if I used a different type of plants like tomatoes or ornamental flowers would the outcome be the same? I wonder if I used a more concentrated potassium salt solution or a more concentrated sodium salt solution would the outcome be the same?
If I were to conduct this project again I would definitely make sure the soybeans had more light, preferably sunlight during the summer. I’d use far more plants in each group. I’d test the water to make sure it actually had some potassium or sodium salt dissolved in it. I’d also grow the plants for many more weeks.
Researched by --- Josh M
