APES: Soil Analysis Lab
PART ONE: GENERAL OBSERVATIONS
Choose one of the soil samples. Remove any stones, roots, grass, or thatch from the sample and place the
pieces in the trash. Makes note of the surroundings where the sample was collected. Factors such as plant
life, buildings, walkways, and paved areas may influence some of your tests and give clues about why you
got the results you measured.
Now take a look at your soil. What do you see? Perhaps you will see organic matter, worms or insects.
Observe the various particle sizes in your soil. Are they large or small? Take a hand magnifier and look more
closely. What do you see now that you did not see before?
Take a Petri dish and put some soil in it. Observe this soil under a stereomicroscope. What can you see not
that you couldn’t see before?
Record the following on your data page.
General Observations
Abiotic Components
Biotic Components
PART TWO: SOIL FERTILITY ANALYSIS
Read the following and answer the questions on your data page.
Four variables are important in determining the fertility of soils. They are: pH and the amount of nitrogen,
phosphorous, and potassium. The values of each of these components can serve as a limiting factor for the
growth of plants. Use the soil test kits and directions at the table to determine the values of each variable
for your sample.
Follow the directions included at the table.
Record the results on your data page.
pH:_______
Nitrogen:________ Phosphorous:_________
Potassium: _________
PART THREE: SOIL TEXTURE
Read the following and answer the questions on your data page.
Soil is made of mineral particles belong to three size categories: clay, silt, and sand. The size of soil particles
is important. Large particles of sand allow empty space for air and water to enter the soil. Smaller silt and
clay particles help holed the water in a soil so that it does not drain away too quickly to be of use to plants.
The ratios of these materials, or texture, can be determined qualitatively and quantitatively.
Qualitative Test:
Refer to the Soil Texture by Feel Flow chart. Follow the directions to determine what type of soil you have.
Have everyone in your group perform this activity. Compare results.
Answer the following question on your data page.
What kind of soil do you have? Why do you think this?
APES / Chapter 8- Earth’s Systems / Soil Analysis Lab
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Quantitative Test:
1. In a 50-mL snap seal container, place about 25-30 mL of your soil sample.
2. Add enough water to saturate the soil completely and then keep adding water until the level gets to
about the 40-mL mark.
3. Add 5-6 drops of ammonium hydroxide (household ammonia) to the jar.
4. Seal the container and shake the whole apparatus until the soil and water completely mix to make freemoving slurry. Be sure to break up any lumps in the soil. Do this for at least 1 minute.
5. Let the container stand for one day
6. After settling for one day, study the soil in the container carefully. The sand will be easily identifiable
because if you can see the individual particles then it is sand. The silt
should form above the sand. The clay will be a thin third layer (in our
sandy soils) lying on top of the silt. Mark these layers with a Vis-a-Vi
marker.
7. Measure the total depth of soil in the bottle, in millimeters (mm). Then
measure the depth of each layer. If the clay fraction is still in part
suspended (as indicated by cloudy water), add 1-2 mm to the clay reading
depending on the density of the suspension.
Record these measurements on your data page.
Total Height: ___________cm
Sand:
___________ cm
Silt:
___________ cm
Clay:
___________ cm
Answer the following question on your data page.
What type of soil do you have? Use the Soil Triangle.
How does your answer compare to the qualitative method?
PART FOUR: CARBONATE ANALYSIS
Add a few drops of vinegar to the soil sample in the Petri dish. If this creates a lot of bubbling, you have a
high level of free carbonates in your soil. A little bubbling means a moderate to low level of free
carbonates in the soil. No bubbling means no carbonates in the soil.
Circle you soil’s free carbonate level on your data page: none
low
medium
high
PART FIVE: DRY PERCOLATION RATE (INFILTRATION)
Materials:
 2 plastic cups
 soil samples
 50 ml graduated cylinder
APES / Chapter 8- Earth’s Systems / Soil Analysis Lab
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Read the following and answer the questions on your data page.
A soil's permeability is a measure of the ability of air and water to move through it. Permeability is
influenced by the size, shape, and continuity of the pore spaces, which in turn are dependent on the soil
bulk density, structure, and texture. Most soil series are assigned to a single permeability class based on
the most restrictive layer in the upper five feet of the soil profile. However, soil series with contrasting
textures in the soil profile are assigned to more than one permeability class. In most cases, soils with a
slow, very slow, rapid, or very rapid permeability classification are considered poor for irrigation.
Infiltration is the downward flow of water from the surface through the soil. The infiltration rate
(sometimes called intake rate) of a soil is a measure of its ability to absorb an amount of rain or irrigation
water over a given time period. It is commonly expressed in inches per hour. The infiltration rate is
dependent on the permeability of the surface soil, moisture content of the soil, and surface conditions
such as roughness (tillage and plant residue), slope, and plant cover.
Coarse textured soils such as sands and gravel usually have high infiltration rates. The infiltration rates of
medium and fine textured soils such as loams, silts, and clays are lower than those of coarse textured soils
and more dependent on the stability of the soil aggregates. Water and plant nutrient losses may be
greater in coarse textured soils, so the timing and quantity of chemical and water applications is
particularly critical on these soils.
Procedure:
1. Take one of the plastic cups and poke three holes in the bottom.
2. Fill that cup halfway with one of the soil samples. Pack it down lightly to avoid having large air spaces.
3. Have one of the lab partners hold the cup with the soil above an empty cup with no holes so that they
can catch the water as it drips through the soil.
4. The other lab partner should measure out 50 ml of water and slowly pour it on top of the soil.
5. Time for 1 minute and then set the cup with the soil aside. (Be careful where you place the cup. It will
continue to drip water, so put it over a cup or beaker.)
6. Pour the water from the second cup into the graduated cylinder to see how much of the 50 ml came
through.
7. Record the volume on your data page. Repeat two more times.
Volume of Water (ml)
Soil Sample 1
Soil Sample 2
Soil Sample 3
___________
___________
___________
PART SIX: SOIL POROSITY
Read the following and answer the questions on your data page.
Porosity is the amount of air space in a soil sample. Porosity is important because it determines the ease
with which water, oxygen, and nitrogen can work their way down to the roots of plants. The creation of
aquifers also depends on pore spaces between soil particles.
To determine the porosity of your soil, fill a 250 mL beaker to the 50 mL mark with dried soil and tamp
down gently. Fill a 100 mL graduated cylinder to the 50 mL mark with water. Gently pour the water onto
the surface of the soil until the soil is completely saturated and water just starts to pool up on the surface.
Measure the amount of water left in the graduated cylinder. The amount of water used is the amount of
air space in your sample. If the soil is extremely porous, you may need to refill the graduated cylinder.
Record your data on your data page.
APES / Chapter 8- Earth’s Systems / Soil Analysis Lab
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PART SEVEN: SOIL CONSISTENCE
Determine which of the following is closest to your soil and circle the number on your data page.
1.
Loose – soil flows easily through one’s hand like sand
2.
Friable – soil does not flow, but it does crumble easily between one’s fingers
3.
Firm – soil resists crumbling and it takes effort to break it into pieces
4.
Extremely Firm – soil is cement-like and feels like it might need a hammer to break it into pieces.
Soil Analysis Lab Questions
Answer the questions on your data page.
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Could the size of the soil particles affect life of microorganisms living in the soil? Explain.
Why would a farmer need to know the soil permeability of his land?
What is the relationship between soil texture and water?
What are the causes of erosion?
What can be done about erosion problems?
Which type of soil would be more subject to erosion?
What do you think gardeners and farmers could do to minimize contamination of groundwater from
certain compounds in fertilizers?
Is there a relationship between elements found in your soil sample and the pH? Explain.
What environmental effects does adding the wrong type of fertilizer have?
How are the movement of nutrients and pollutants different through each soil type?
Imagine a sloping field of very sandy soil and a sloping field of soil with very high clay content, each
with an identical drainage ditch at the bottom. In a prolonged, heavy downpour, which ditch would be
more apt to flood than the other? Why?
If you had two fields of crops, one in which the soil was mostly sand and the other mostly clay, which
one would you have to water most often and why?
Would your soil be suitable for growing crops? Why or why not?
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