Earth Science
Cumberland Prairie Plot Soil Analysis
Name of experiment: Chemical Composition of the Soil Experiment
Purpose of experiment: To find out what kinds of chemicals are in the Prairie Plot’s soil.
Materials:
Soil
Test Tubes
Test Tube Stoppers
Test Tube rack
Eye droppers
Labforms
Safety Glasses
Pipettes
Distilled Water
Plastic spoons
Cups
Waste cup
Soil Extract (made by us)
Chemical Testing solutions / testing paper strips:
Sodium Hydroxide solution
Magnesium Reagent
Acetic Acid solution
Hydrochloric Acid
Phosphorous Reagent
Tin pieces
pH testing strip
Nitrate testing strip
Sulfate testing strip
Ammonium test paper
Ammonium Oxalate solution
Potassium test paper
Iron test paper
Steps (Procedures):
1. Test for organic matter by putting 1 spoonful of soil to test tube; add 3ml of Sodium
hydroxide solution in the test tube; add 3 ml of distilled water; stopper the test tube and
shake it well. Store in test tube rack overnight. Observe and record data.
2. Test for pH (acidity) by putting a spoonful of soil in the center of the labform; pipet enough
distilled water to just moisten the soil; add 5 drops. Let the soil sit for 30 seconds; press the
soil to the side of the labform to release the water; using a pH testing strip, dip in the water
and compare the color of the strip to the chart.
3. Test for carbonates by adding ½ spoonful of soil to the labform; add 10 drops of
Hydrochloric acid solution to the tube; look for bubbles indicating that carbonates are in the
soil.
4. Make a soil extract that will be used for the rest of the soil tests by adding a spoonful of soil
to the test tube; pipet 8 ml of distilled water in the test tube; add 2 drops of acetic acid
solution to the test tube; stopper the tube shake for about a minute; let it sit overnight. (We
did this three times.) The next day we poured off the water into a plastic sample cup.
5. Test for nitrates by pipeting 20 drops of soil extract (S.E.) and then dipping a nitrate testing
strip in the solution for 1–2 seconds; remove and wait for 60 seconds and then record.
Nitrates are present if the lower part of the strip turns red. Nitrites are present if the upper
part of the strip turns red.
6. Test for phosphates by adding 5 drops of phosphorous reagent to 20 drops of S.E.; drop a
piece of tin into the tube and wait 15 to 20 seconds; Record– if solution is blue – indicates
the presence of phosphates: the darker the blue the higher amount of phosphates.
7. Test for sulfates by adding 20 drops of the S.E. into a tube and then dip the sulfate testing
strips (reagent end); wait for 2 minutes; observe and record results ~ If one or more pad in
the strip turns yellow/orange, indicates sulfates. The more reagent pads with positive
reaction indicate a higher amount of sulfates.
8. Test for ammonium by placing a piece of ammonium testing paper in the depression (bowl)
in the labform; pipet 2 drops of S.E. onto the test paper; add 7 drops of sodium hydroxide
solution; a brownish-yellow color shows ammonium ions are present.
9. Test for magnesium by putting 20 drops of S.E. into a test tube; add 1 drop of sodium
hydroxide solution into it; add 1 drop of magnesium reagent into the S.E.; let it sit for 30
seconds; A brownish color indicates a medium amount of magnesium.
10. Test for calcium by pipet 20 drops of S.E. into a labform; add 2 drops of ammonium oxalate
into the S.E.; a white cloud appears indicating that calcium is present. Record.
11. Test for potassium by getting a piece of potassium testing paper and place it in the center
well of the labform; pipet 1 drop of S.E. onto the testing paper; add 2 drops of phosphorous
reagent to the same spot on the paper. An orange or red spot shows the presence of
potassium ions. The paper surrounding this spot will turn yellow, indicating no potassium;
record.
12. Test for iron by placing a piece of iron test paper in a clean depression well in the labform;
pipet 1 drop of S.E. onto the test paper. A brownish-red spot indicates the presence of iron.
Results (Including drawing if needed):
Of the eleven different chemicals we were testing for, there were four chemicals present
in our soil. They were organic matter, calcium, magnesium, and iron. Plants that can tolerate
these chemicals seem to grow well in our prairie plot. Plants that require high amounts of
nitrogen and phosphorous might have problems with keeping their root systems. We created a
table that follows indicating the results for each of the chemicals we tested for.
Soil Analysis Table:
Material
Results
Organic Material
(scale of 0-5)
4
pH (1-14)
6
Nitrates (present or absent)
Absent
Carbonates
(high, medium, low, none)
None
Phosphates
(high, medium, low, none)
Low
Sulfates
(high, medium, low, none)
Low
Ammonium
(present or absent)
Absent
Magnesium
(high, medium, low, none)
Medium
Calcium
(high, medium, low, none)
High
Potassium
(present or absent)
Absent
Iron (present or absent)
Present
Conclusions:
We have learned about the chemicals that are in soil, especially about the soils that are at
our school’s prairie plot. If we tested a sample of soil from Toledo, it would probably be
different from the school’s sample. The prairie plants that are in our plot change the chemical
content of the soil as well. The soil testing kit that we bought was easy to use.