Download organisms in compacted soil

ORGANISMS IN
COMPACTED SOIL
Introduction
Soil is essential to a healthy ecosystem. Because it is not alive, soil is
described as an abiotic environmental factor. There are, however, many
biotic, or living, factors in soil, like fungi, insects, and worms. Their jobs
are to break down organic matter and make it available to other living
things. The burrows of these subterranean residents help aerate the soil
by making it possible for oxygen to penetrate. Different kinds of soil,
shown in Figure 1, can support different populations of living things.
Sandy soil, which consists of large particles that do not compact easily,
loses water and nutrients quickly. Clayey soils are made of small particles
that are easily compacted. This type of soil holds nutrients and moisture,
but it often has poor drainage and aeration. Loam, a mixture of sandy and
clayey soils, holds moisture and nutrients very well and does not compact
easily. Loamy soils often provide optimal conditions for living things.
Some factors that cause soil compaction are heavy foot or vehicular traffic
and falling water. In this experiment, you will observe the way earthworms
respond to different soil types and to compacted and loose soil.
sand
loam
Figure 1
Walker/Wood-JNEOF Fig 1 Pg 3.3-1)
rev.10/20/05
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clay
ORGANISMS IN COMPACTED SOIL
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Time Needed
55 minutes
What You Need
F 2 quart jars or 500-milliliter (ml) beakers
F sandy soil (about 1 cup)
F clayey soil (about 1 cup)
F clock or watch with a second hand
F 2 earthworms
F 2 sheets of newspaper
F small paper cup
F science notebook
Safety Precautions
Handle earthworms with care, touching them as little as
possible. After working with earthworms, wash your hands
with soap and water. Please review and follow the safety
guidelines.
What You Do
1. Fill one jar with sandy soil and the second jar with clayey soil. To
avoid compacting the soil samples, do not press them down into
the jars.
2. Find out how long it takes an earthworm to dig completely into the
sandy soil. To do so, place one earthworm (Figure 2) in the jar of
sand. Record the time (in minutes and seconds) in your notebook as
“starting time.” When the earthworm has completely buried its body
in the soil, record the time as “final time.” Subtract the starting time
from the final time to determine how long it took the earthworm to
bury its body in the sand.
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ORGANISMS IN COMPACTED SOIL
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earthworm
anus
clitellum
mouth
Figure 2
Figure 2
3. Repeat step 2 with the second earthworm and the jar of clayey soil.
4. Remove the sand and earthworm from the first jar by gently pouring
the sand onto a piece of newspaper. Gently lift the earthworm with
your hands or scoop it up with a small paper cup. Set the earthworm
aside.
5. Fill the jar with the sand again. This time, use your hand to compact
the sandy soil in the jar.
6. Place the earthworm in the jar of sandy soil. In your science
notebook, record the starting time. Watch the earthworm until it has
completely buried its body in the soil, then record the final time.
Subtract the starting time from the final time to determine how long
it took the earthworm to bury its body in the compacted sand.
7. Repeat steps 4 through 6 with the second earthworm and the jar of
clayey soil.
Observations
1. In which case was the worm able to dig through the soil
the fastest:
a. In loose sand or in compacted sand?
b. In loose clay or in compacted clay?
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ORGANISMS IN COMPACTED SOIL
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2. In nature, do you think that earthworms are more likely to
be found in loose soil or compacted soil? Explain your
reasoning.
3. If you wanted to locate a few earthworms, where would
you expect to find them:
a. In the soil that makes up a path between the school
and the bus stop?
b. In the soil that is located beneath the shrubbery?
Explain your reasoning.
4. How do earthworms help aerate the soil?
Want to Know More?
See Our Findings.
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SAFETY PRECAUTIONS
Review Before Starting Any Experiment
GENERAL
• Always obtain your teacher’s permission for experiments performed
at school, and your parent’s permission for experiments performed
at home, before attempting any experiment.
• Read all instructions for an experiment before starting the
experiment, and follow the directions exactly as they appear in
this volume.
• If an experiment requires adult supervision, do not perform the
experiment unless you have an adult supervising you the entire
time you are performing the experiment.
• Wash your hands before the start of and after each experiment
you perform.
• Keep your work area clean.
• Never eat or drink while performing an experiment. Never taste a
substance used in an experiment unless you are told that it is safe
to do so.
• Be aware of the location of safety equipment you may need in an
emergency, such as running water, an eyewash if you are at school,
and a fire extinguisher.
• If you are going outside, make sure you have permission to go
from your teacher and parent. Take a buddy with you, and dress
appropriately for the weather. Make sure you or someone who
accompanies you is familiar with the area, and bring along a firstaid kit in case of emergency.
• Never look directly into the Sun.
CHEMICAL SAFETY
• Always wear goggles when working with chemicals, such as acids
and bases, and near heat sources like flames. If at all possible,
avoid wearing contact lenses when working with chemicals.
• If any substance gets into your eyes, notify an adult (e.g., your
teacher or parent) immediately, and flush your eyes with running
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SAFETY PRECAUTIONS
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water for at least 15 minutes. Do not mix chemicals unless you are
told to do so by a teacher or parent.
• Never touch, taste, or smell chemicals unless instructed to do so.
• Keep chemicals in closed containers when they are not in use.
• Dispose of all chemicals properly. Do not pour any chemicals or
solids down the drain unless instructed to do so.
• Use safety gloves and a plastic apron when handling chemicals. If
any chemicals spill on your skin, rinse the affected area with
running water for at least 10 minutes, and notify your teacher or
parent immediately.
• Take precautions to avoid spilling chemicals. If a chemical spills on
any surface, notify your teacher or parent immediately to assist
with clean-up.
• Exercise caution when using sharp instruments such as knives or
scissors. Always cut away from yourself, not toward yourself. If you
cut yourself, notify your teacher or parent immediately.
GLASSWARE
• Clean glassware when you are finished with the experiment.
• Be careful when using glassware. If a piece of glassware breaks,
have an adult assist you in clean-up to avoid injuries from broken
glass. Never use broken or damaged glassware.
FIRE SAFETY
• Do not heat glassware that is not completely dry. Do not pick up
hot glassware without heat-resistant gloves or tongs.
• When heating glassware, keep it away from yourself and from
others.
• Do not heat anything unless instructed to do so by a teacher or
parent.
• Do not heat substances in a closed container.
• After an experiment, make sure that all heating sources are off
and that all flames have been put out.
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SAFETY PRECAUTIONS
• Do not reach across such heating sources as flames.
• If you have long hair, tie it back, out of the way. Do not wear
clothing with loose sleeves, scarves, bows, ties, or anything else
that may hang into a fire. Do not wear long earrings.
ELECTRICAL SAFETY
• Do not touch electrical equipment when your hands are wet.
• Do not plug several electrical devices into one outlet or use an
extension cord.
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