Soil: A Natural
Resource
SOL 3.7
By
Ellen Benegar
Suffolk Public Schools
Why is soil important?
• Many plants grow in soil.
• Soil provides support and nutrients for
the plants.
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How is Soil Created?
• Weathering is when weather, water and
living things break down rocks and
create soil.
• Weathering takes place over many
years.
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http://www.geography4kids.com/files/land_weathering.html
What are nutrients?
• Materials that plants and animals need
to live and grow.
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What makes up soil?
•
•
•
•
•
Rock
Clay
Silt
Sand
Humus
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3 Layers of Soil:
topsoil, subsoil and bedrock
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What is topsoil?
• Topsoil is the
upper surface of
soil.
• It is a natural
product of
subsoil and
bedrock.
• Topsoil is the
best for plant
growth.
What is Subsoil and Bedrock?
• Subsoil and bedrock are layers of soil
under the topsoil that are formed over a
long period of time by water.
• Subsoil and bedrock aren’t as good for
growing plants as topsoil.
What is Humus?
(“HYOO-mus”)
• Humus is decayed or dead matter in
soil.
• It adds nutrients to the soil.
• Humus is found in topsoil.
http://www.ngu.no/Kola/cd2-22b.gif
What is Clay?
• Clay contains small particles of soil that
hold water well and provides nutrients.
www.dahlias.net
What is Sand?
• Sand is made up of small grains of
worn-down rock.
• It has few nutrients.
• Sand doesn’t hold water well.
www.dahlias.net
What is Silt?
• Silt is composed (made up of) very
small broken pieces of rock.
• Its particles are larger than clay and
smaller than sand.
www.hi.is
Fill in this diagram of soil
layers using the terms:
subsoil, bedrock and topsoil.
Best soil for plants
Best soil for
plants
Not good for
growing
plants
Formed
over a long
period of
time
1. In which soil type did the plant grow the slowest?
2. In which soil type was there the greatest amount of
growth?
3. What is the worst soil to grow plants in according to
the chart?
Plant Growth in Different Soil
Types
2
# of 1.5
Inches 1
Grown 0.5
0
Day 5 Day Day Day
10 15 20
Days of Growth
Humus
Clay
Silt
How can soil be conserved?
• Proper use of farming
• Proper use of mining
• Proper use of cutting down of trees to
avoid erosion
Review
• Name the 5
components of soil.
Check answer here
• What are nutrients?
Check answer here
• Why is soil important?
Check answer here
• What is weathering?
Check answer here
• Fill in this chart to
compare 4 types of soil.
Humus
Clay
Sand
Silt