Science Fair Project
Effects of Salt Water on Plant Growth
Jimmy Ester
.Mr. Williams; 7/8 Science
A.N.L.C.
The Question:
What affect will a 20% saline solution have on the
growth of a bean plant?
Project Overview
Irrigated agricultural regions of the Southwest United States are
accumulating high concentrations of dissolved mineral salts in soil
due to overuse and recycling of water resources . When salt
concentrations reach high levels, the soil becomes “sodic.” Sodic
soils are characterized by a poor soil structure: they have a low
infiltration rate, they are poorly aerated and difficult to cultivate.
Thus, sodic soils adversely affect the plants' growth.
This experiment will illustrate the effect of water containing a
high concentration of salt on the growth of plants.
Research
Soils that contain a harmful amount of salt are often
referred to as salty or saline soils. Soil, or water, that has a
high content of salt is said to have a high salinity.
A soil may be rich in salts because the parent rock from
which it was formed contains salts. Sea water is another
source of salts in low-lying areas along the coast. A very
common source of salts in irrigated soils is the irrigation
water itself. Most irrigation waters contain some salts.
There are two types of salt problems which are very
different, those associated with the total salinity and those
associated with sodium. Soils may be effected only by
salinity or by a combination of both salinity and sodium.
Variables
 Control: The control for this experiment will be half
of the bean plant population receiving water from the
City of Phoenix supply.
 Independent variable: The plants in the group
receiving the treatment of being watered with the salt
solution are being tested for ability to thrive with
saline solution.
 Dependent variable: The dependent variables to be
measured will be actual plant height and leaf color.
Hypothesis
Bean plants receiving the 20% saline
solution will die or fail to thrive as
compared to the control bean plant
group.
Materials
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Two 1000 ml beakers
Digital Balance
Table Salt- 20 g/L
20 pinto beans
20 ¼ cup peat pots
Outdoor area receiving appox. 6 hrs. of sunlight per day
30 cm ruler
Kellogg potting mix- 150 g/pot
60 liters of tap water
60 liters of 20% salt water
Excel growth log template
Digital camera
Procedure
1.Establish an outside area that receives approximately 6 hours of sunlight per day that
will accommodate 20 pots2. Fill 20 ¼ cup peat pots with 150 grams of Kellogg potting mix per pot3. Place one pinto bean in each pot at a depth of 3 centimeters.
4. Divide plants into two groups of ten.
5. Label one group “Control” and the other group, “Treatment.”
6. Place both groups in the outside sunlit area determined in step #1.
7. Label beakers #1 and #28. Fill beaker #1 with 1000 ml of tap water.
9. Weigh 20g of salt, add to beaker #2. Fill the beaker up to the 1000ml line. (This will
result in the 20% solution).
10. Water the control group of plants with 100ml of water, from beaker #1, twice per day7:00AM and 5:00 PM. Refill the beaker as needed from the City water supply11. Water the treatment group with 100ml of water from beaker #2. Twice per day,
7:00AM and 5:00PM- Prepare more solution as needed describer in step 912. Measure plant growth and observe leaf color every 3 days for 4 months.
13. Enter data in Excel program, analyze data, report results, list conclusions.
Data/Observations
Bean Plant Growth: Treatment/Control
7
6.2
O
b
s
e
r
v
a
t
i
o
n
6
5
4.4
4.2
4
3.1
3
2.32.1
2
1 1
Series1
Series2
1.31.3
1
0 0
0 0
0 0
1
2
3
0.10.1
0
4
5
6
Growth in Centimeters
7
8
Color: The treatment plants started to yellow at
observation four where the control maintained a
healthy deep green color. The color change
corresponded to the slowing of growth relative
to the control plants.
9
Conclusion
The salt solution eventually killed 100% of the treatment plants.
The treatment group failed to thrive in growth and remained pale or
yellow throughout the growth cycle , which impeded photosynthesis.
The control group continues the thrive and have actually produced
been pods.
The hypothesis: “Bean plants receiving the 20% saline solution
will die or fail to thrive as compared to the control bean plant
group.” has been proven correct.
Works Cited
“Evaluating Recycled Waters for Golf Course Irrigation”
http://turf.lib.msu.edu/2000s/2004/041125.pdf
“Irrigation Water Quality”
http://www.fao.org/docrep/R4082E/r4082e08.htm#7.6.1
“IRRIGATION WATER QUALITY STANDARDS AND SALINITY MANAGEMENT”
http://agnewsarchive.tamu.edu/drought/DRGHTPAK/SALINITY.HTM