The effect of NaCl(s) on grass
Schreefel, R. & Eldewieh, S.
Het 4e Gymnasium, The Netherlands
Received April 2011
Summary
Road salt is widely used in regions with cold winters in order to combat slippery roads and to avoid
dangerous situations that can cause lethal accidents. This is the positive side of spreading salt. Some
years there is more salt used than others according to the severity of the winter. The use of more salt
there came negatives sides; road salt can cause for example corrosion on cars and motorcycles.
And salt used in the winter solves in the water and ends up in the groundwater. It is widely known that
salt is not very good for plants. That is why not all plants can grow close to the see because of the salt.
This is why we wanted to study how big the effect of salt is on growing plants.
© 2011 Schreefel&Eldewieh. All rights received
Introduction
During cold winters citizens expect the
government to deice the road with as much salt
as needed. But the governments do not spread
to much salt, because it is very expensive and
it can have environmental effects. It is widely
known that salt isn’t good for plants and
animals. However it is not clear how big the
effect of the salt is.
That is why we wanted to do our research
about the effect of road salt on the
environment. We hadn’t unfortunately the
possibility to do our research on a big area.
Therefore we have made a small preparation
with grass and done our research about the
effect of NaCl on the growth of grass. This had
an advantage: we could control the amount of
salt in the water and our results would not be
affected by other variables.
Experimental procedure and approach
We took ten identical glass petri, all numbered,
and each one filled with two filters with a layer
of cotton wool above it. Then we put 30 seeds
of grass (pokon grass repair set of Gamma) on
the top layer of cotton wool. All the glass petri
were then put down in a tray under a
fluorescent tube.
We made two lines with each five petri
glasses. We had decided to give the bottom
line from day one a NaCl-solution. The second
line received water after 2 weeks. The different
solutions that we have used are given in the
following table:
Number of the
glass petri
1
2
Percentage of NaCl in the
added water
Only water
10gram/l NaCl
3
4
5
6
7
8
9
10
30gram/l NaCl
50 gram/l NaCl
100 gram/l NaCl
Only water
10gram/l NaCl from week 2
30 gram/l NaCl from week 2
50 gram/l NaCl from week 2
100 gram/l NaCl from week 2
Table1: Different solutions of NaCl.
We gave the seeds water every 3 or 4 days.
Before we gave them the water we checked
how far the seeds were with growing. We gave
them each time 50 ml of the NaCl-solutions.
After a while as we were working on our
research we experienced that after the water
was evaporated there remained a hard layer of
salt. This layer grew every time we gave the
seeds water.
So we started again with the same approach
but with new quantities of salt. The new
solutions that we have used are given in the
following table:
Number of the
glass petri
1
2
3
4
5
6
7
8
9
10
Percentage of NaCl in the
added water
Only water
1gram/l NaCl
3gram/l NaCl
5 gram/l NaCl
10 gram/l NaCl
Only water
1gram/l NaCl from week 2
3 gram/l NaCl from week 2
5 gram/l NaCl from week 2
10 gram/l NaCl from week 2
Table 2: The new solutions of NaCl.
Data gathering and analysis
We looked every 3 or 4 days how the seeds
grew and we wrote all our notations down. We
wanted to use a ruler to measure the length of
the grass. We also judged the developments
with the eye.
looked if dirt or loam can hold the water better
than the cotton wool that we have used.
We also think that it was unnecessary that we
used a lamp for the seeds to germinate. Light
is used for photosynthesis what seeds still
don’t do.
We still have not completed our research. We
can see what we have done till now as
information to build on and do other tests. We
have come with a new preparation that we can
see as our conclusion. It will look like the
picture beneath.
Figure 1: The layer of salt.
Results
After four weeks of waiting and giving the
plants water we came with the following
results: grass seeds cannot grow well in an
environment with water containing 1 gram of
salt per liter of water. We also concluded that
not every single seed germinates.
Conclusion and discussion
When we look back at our results we can
induce that our approach has not worked well.
We have seen that we have used a NaClsolution with too big amounts of salt. As
results there arose a layer of salt on the seeds.
Our first set of grass seeds did not grow, so we
must started again with lower salt percentage
in the water. We discovered that the new
amount of salts in the solutions are also too
much.
Another problem was that the water in the
NaCl-solution evaporated so quickly that we
had to refill the glass petri every day. That was
for us a huge problem. If we gave the seeds to
much water, so we had not refill it so much,
they drowned. And we did not know how bad
it is for seeds to have no air.
We also know now that not every seed that
you plant will germinates and become a blade
of grass. It may be due to the type of seeds that
we have used, but it could also be the place it
was lie. The cotton wool that we have used
was not perfectly equal. This caused that seeds
in the deeper parts got more water what can
possibly ensure that they grow better that
other-placed seeds.
What we could have done was to look if loam
was a better option to use, because in the
nature seeds grow in dirt. Next time we also
Figuur 2 New preparation
We will cut a coffee filter from one side so we
can see inside it. We will hang the filter up and
it will be connected with the different NaClsolution by two or more strips. This always
keeps the seeds wet and with this we will be
avoiding one of our problems.
We will also plant new seeds in loam and to
see how big the effect of salt on grass seeds
and the environment is and to come with clear
figures.
The big questions about road salt will still be
unanswered. How big is the effect of salt on a
bigger scale? And how different is it in
different countries? Some researchers have
tried to find an answer on it. And will there
ever a substance developed that can replays
salt? The time will reveal the answers…
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