Name__________________________
SALINIZATION LAB INTRODUCTION
In Australia, where the climate is dry and precipitation is feeble, farmers and cropland
owners lose nearly a billion dollars a year due to degradation of the soil. This occurs
because water-soluble salts accumulate in the upper-rooting zone, thus hindering the
growth of crops by limiting their ability to take up water. The process of such is called
salinization and is a profound threat to food security and the environment.
Learning about salinization is important because it damages approximately one-tenth of
the world’s irrigated land and reduces irrigated land areas by 1-2% each year.
Salinization occurs where arid or semi-arid soil is present. In areas that experience an
ample amount of rainfall, the development of saline soil is hindered due to leaching,
which is the downward movement of salts.
Salinization may be caused by either natural processes or because of human practices.
The presence of soluble salts (such as sulfates of sodium, calcium, and magnesium), a
high water table, a high rate of evaporation, and low annual rainfall are conditions that
are necessary for the formation of salinization. Some natural landscape features allow
dissolved salts to accumulate in water. Once this water evaporates, the salt concentration
consequently increases. Thus, salinization can occur this way as well.
Other natural sources of salts in soil include the decomposition of rocks and minerals
through chemical weathering. Nearly all types of water (with the exception of natural
rainfall) contain dissolved salts. Once plants use the water, they leave the salt content
behind, allowing it to accumulate in the soil. The restriction of adequate water drainage
within the soil can also contribute to salinization. This is because the water will
eventually evaporate, leaving the salts behind to accumulate. Areas with irrigation are
also vulnerable to salinization, for a higher water table carries salts to the surface because
of high evaporation demand.
Although potentially destructive, there are several ways to prevent and correct
salinization. Provided that there is sufficient natural drainage, it might help to use a bit
more water than plants actually need. This would reduce the salt concentration by
leaching salts past the root zone and into the aquifers, which would then wash away the
unwanted salinity.
Various forms of drainage, such as ditches and underground pipes, can be constructed to
take water with high levels of salt away. In the case where an area experiences extreme
salinization and can no longer sustain agriculture, the land may be rehabilitated through
flooding. Though costly, this method would successfully wash away superficial salts.
One of the more practical ways to prevent salinization is through more efficient use of
irrigation water. For example, drip irrigation, where a metered amount of water is fed to
the area around plants, is better than surface irrigation, which could possibly cause salt
contents to accumulate.
Preventing the spread of salinization and reclaiming the lands that have already been
substantially salted are crucial in securing the stability of the global economy and the
Name__________________________
environment of the future. Salinization threatens approximately 10 percent of the world’s
grain harvest alone. By learning about the process and effects of salinization, one will
obtain a better understanding of the need to address the issue.
Lab Objective
To understand how salinization affects plant growth.
Question
How does varying levels of salt affect mung bean seed germination?
Hypothesis
Materials:
Petri dishes
Graduated Cylinders
Flasks and Beakers for mixing solutions
Distilled Water
Paper Towels
Tweezers for seed placement
Labels
Balances
Mung bean seeds
Procedure for making salt solutions
HINT: 1 mL of water weighs 1 gram
Group
Salt Concentration
1
0%
2
.01%
3
.1 %
4
.5 %
5
1.0%
6
2.0%
7
3.0%
8
4.0%
Amount Water (mL) Amount salt (g)
100
0
99
1
Procedure:
1. Set up 8 petri dishes with 2 paper towels cut to fit inside
2. Label the petri dishes with salt concentration and initials
3. Evenly space 10 mung bean seeds throughout your dish between the paper
towels
4. Pour 10 mL of appropriate salt solution into each dish
5. Place dishes in appropriate place under grow lights
6. After three days count and record the number of seeds that germinated
Name__________________________
Data:
Salt
Concentration
0%
.01%
.1 %
.5 %
1.0%
2.0%
3.0%
4.0%
G1
G2
G3
Mung Bean Seed Germination
G4
G5
G6
G7
G8
Average
Analysis:
1. How does increasing salt concentration affect seed germination?
2. Why does increasing salt concentration affect germination?
3. In agricultural lands, what causes salinization of soils?
4. What can be done to prevent the salinization of soils?
5. How might genetic engineering solve this problem?
%