Download WHAT IS SOIL? - Duplin County Schools

This PowerPoint explains and reports important concepts students should learn and master in an Earth Science unit.
The ideas presented should be understood by upper elementary and middle school student according to most state
science standards as well as Next Generation Science Standards (NGSS).
The concepts covered in this PowerPoint, as well as related activities and materials, are appropriate for upper
elementary and middle school science classrooms. Concepts are differentiated by a colored shape code:
Slides with a green circle deal with basic key ideas and understandings meant for upper elementary (grade 3-5)
students. These concepts can or should be reviewed with intermediate/middle school (grade 6-8) students.
Slides with a blue square deal with intermediate key ideas and understandings meant for middle school students.
These concepts may be appropriate for high-achieving upper elementary students. According to NGSS, some of
the “traditionally intermediate” level concepts are now recognized as upper elementary concepts.
Slides with a black diamond cover advanced concepts. Some of these concepts may be appropriate for your
intermediate students. Sometimes it helps students better understand the how and why of intermediate concepts
if they are introduced to advanced concepts.
This PowerPoint is meant to help students gain a first-order learning of Earth Science concepts. Students should be
able to remember and understand the information presented. Additional activities available for purchase at my store
will help students apply, analyze, create and synthesize knowledge important to a complete unit covering these
concepts.
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© Stephanie Elkowitz
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Soil
Living & Nonliving Parts of Soil
Formation of Soil
Soil Textures
Types of Soil
Layers of Soil
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© Stephanie Elkowitz
• Soil or “dirt” covers the
ground and is like the
skin of Earth.
• Soil covers all parts of
Earth’s surface,
including the “ground” of
oceans, lakes and other
bodies of water.
Soil, Rocks & Minerals
What is soil?
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© Stephanie Elkowitz
• Soil is a mixture of minerals,
water, air and organic matter
that formed from decomposed
remains of plants and animals
and waste produced by living
things.
• Soil also includes living things
such as microorganisms, fungi
and insects.
Soil, Rocks & Minerals
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© Stephanie Elkowitz
• Soil is important because:
– Plants extract water and nutrients
from soil and use soil to anchor
themselves.
– Organisms such as bacteria, fungi
and animals live in soil.
– Soil helps cycle nutrients and
substances, such as carbon and
nitrogen, in the environment.
– Water precipitates to the ground and
flows along Earth’s surface. Water
seeps into the ground to form
groundwater. Soil filters and cleans
the water.
Soil, Rocks & Minerals
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© Stephanie Elkowitz
• When studying soil, we often consider the living and
nonliving parts of soil.
• The living parts of soil include organism that inhabit soil.
• The nonliving parts of soil include the dead and nonliving
substances that make up soil. These substances make up
the material that we call dirt.
Soil, Rocks & Minerals
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© Stephanie Elkowitz
• There are 5 major nonliving components of soil:
– Sediments: small particles of broken down rock.
– Minerals: important elements needed by living things in the soil,
make up rocks, determine the fertility of soil
– Nutrients: substances in soil that are used by living things to
survive; the most important nutrients are nitrogen, phosphorus and
potassium
– Water: Water is found in between the particles of soil
– Organic Matter: made from dead and decaying organisms
Soil, Rocks & Minerals
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© Stephanie Elkowitz
• Many different living things live in soil or depend on soil:
– Plants: establish their roots in soil to extract nutrients, water and
other substances to help them grow
– Bacteria: help decompose dead organisms and they help “prepare”
nutrients, such as nitrogen, in the soil. Bacteria are plentiful in soil 1 teaspoon of soil can have up to 1 billion bacteria!
– Animals: some animals, such as snakes and groundhogs burrow in
soil, insects (ex. worms) in soil help decompose dead organisms
– Fungi: important decomposers that break down dead organisms
Soil, Rocks & Minerals
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© Stephanie Elkowitz
• Soil can take a long time to form. In fact, soil can take up to
1,000 years to form! There are 4 factors that influence how
fast soil forms:
1. Organisms
2. Topography
3. Climate
4. Parent Material
Soil, Rocks & Minerals
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© Stephanie Elkowitz
Factor #1: Organisms
• Living things known as decomposers help break down dead
organisms into organic matter. Organic matter is an
important part of soil.
• The kind and amount of decomposers in the soil can affect
how fast organic matter forms.
Soil, Rocks & Minerals
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© Stephanie Elkowitz
Factor #2: Topography
• Elevation and slope make up the shape of the land. We call
the shape of land topography.
• Topography affects how fast soil forms. Water travels faster
down steeper slopes. This causes faster soil formation
along steep slopes.
• Elevation and slope are also important to the type of soil
that forms.
Soil, Rocks & Minerals
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© Stephanie Elkowitz
Factor #3: Climate
• Climatic factors, such as precipitation and temperature,
affect how fast soil forms. These factors cause weathering.
• Weathering is breaking down of rock. Weathering is
important to soil formation.
• Increased precipitation and warmer temperature causes
faster weathering, which leads to faster soil formation.
Soil, Rocks & Minerals
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© Stephanie Elkowitz
Factor #4: Parent Material
• Parent material is solid rock and minerals found within
Earth.
• Over time, parent material breaks down to form soil. Some
rocks and/or minerals break down faster than others.
• Softer rock breaks down faster than harder rock.
Soil, Rocks & Minerals
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© Stephanie Elkowitz
• In order for soil to form,
there must first be parent
material. Parent material is
solid rock and minerals.
• Parent material is often
bedrock. Bedrock is hard,
solid rock that covers Earth.
This rock is formed from
different natural processes.
It can become exposed
when overlying soil or rock
erodes.
Soil, Rocks & Minerals
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© Stephanie Elkowitz
• Over time, parent
material is weathered
or broken down into
small particles.
• The most influential
weathering factors are
wind, water and plants.
Soil, Rocks & Minerals
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© Stephanie Elkowitz
• Eventually parent material is
completely broken down into small
particles. Water and gases mix with
the rock and mineral particles.
• Plants begin to grow in the material,
organisms move into the material and
larger organisms roam the surface of
the material.
• Organisms die and decompose into
organic matter, which is incorporated
into the material. Over time, the
material transforms into soil.
Soil, Rocks & Minerals
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© Stephanie Elkowitz
• There are several characteristics of soil. These
characteristics include texture, density, color, consistency
and porosity.
• The most important characteristic of soil is texture.
• Texture is a measure of what the soil feels like. Texture
depends on the size of the particles within the soil.
• Texture determines other characteristics of soil.
Soil, Rocks & Minerals
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© Stephanie Elkowitz
• There are three soil textures:
1. Sand
2. Silt
3. Clay
Soil, Rocks & Minerals
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© Stephanie Elkowitz
• Sand is made of large or coarse
particles with diameters ranging
from 0.05 to 2.00 millimeters.
• Because sand is made of large
particles, it feels gritty or rough.
• It allows water and air to pass
through easily. However,
because it is porous, it does not
hold nutrients or water well.
Soil, Rocks & Minerals
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© Stephanie Elkowitz
• Silt is made of medium-sized
particles with a diameter of 0.002
to 0.05 millimeters.
• Because silt is made of smaller
particles, it is not as rough as sand.
When dry, it feels like smooth
powder. When wet, it feels slippery.
• Because its particles are smaller, it
allows some drainage and air to
pass through but holds onto
nutrients. It can be easily packed
down, which allows less water and
air to pass through.
Soil, Rocks & Minerals
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© Stephanie Elkowitz
• Clay is made of tiny or fine
particles with a diameter less
than 0.002 millimeters.
• When dry, clay feel smooth and
hard. When wet, it feels sticky.
• Because its particles are fine, it
holds onto water and nutrients
very well and does not allow air
to pass through easily. When
wet, clay gets “heavy” from the
water and then becomes very
hard when dry.
Soil, Rocks & Minerals
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© Stephanie Elkowitz
• The three soil textures form mixtures to make up different
types of soil. Each type of soil has a different fraction or
proportion of sand, silt and/or clay.
• There are many different types of soil but we often focus on
the three types below:
1. Sandy Soil
2. Clay Soil
3. Loamy Soil
Soil, Rocks & Minerals
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© Stephanie Elkowitz
• Sandy soil is mostly (but not entirely)
made of sand. Because sandy soil is
mostly sand, it has properties very
similar to sand, the soil texture.
– Sandy soil is dry and gritty. The particles
are large and there are spaces between
the particles - they cannot hold water or
nutrients.
– Water drains quickly through sandy soil
and so it’s usually dry. For this reason,
sandy soil is not good for plants. Plants
cannot extract enough water and
nutrients in order to survive.
• Sandy soil is common at beaches.
Soil, Rocks & Minerals
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© Stephanie Elkowitz
• Clay soil is mostly (but not entirely)
made of clay. Because clay soil is
mostly clay, its properties are most
like clay, the soil texture.
– Clay soil is made of tiny particles that
tend to settle together. This makes it
hard for water and air to pass through.
It also means clay soil holds onto
nutrients tightly.
– Clay soil poor soil for plants. Plants
cannot extract water or nutrients from
clay soil because the soil holds onto
these substances so tightly.
• Clay soil is found everywhere.
Soil, Rocks & Minerals
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© Stephanie Elkowitz
• Loamy soil is made of almost equal parts sand, clay and
silt. For this reason, it has characteristics of all three types
of soil textures.
• Loamy soil is considered to be the ideal soil type. It
contains a balance of all three soil textures – plus organic
matter.
– It holds onto water and nutrients and drains water well. Air moves
freely through loamy soil.
– Loamy soil is the best for plants because of these characteristics.
This soil is just right for plants.
Soil, Rocks & Minerals
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© Stephanie Elkowitz
• Loamy soil makes up fertile lands. These lands are ideal
for farming and other agricultural uses.
Soil, Rocks & Minerals
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© Stephanie Elkowitz
• Most people think soil is just
the “dirt” that covers the very
top of the ground. In fact, soil
is much more than just this
material.
• Soil is actually made of layers.
We call these layers horizons.
Each horizon is distinct and
has its own characteristics.
Soil, Rocks & Minerals
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© Stephanie Elkowitz
• There are 5 major
horizons of soil:
– O Horizon (Humus)
– A Horizon (Topsoil)
– B Horizon (Subsoil)
– C Horizon (Parent
Material)
– R Horizon (Bedrock)
O Horizon
A Horizon
B Horizon
C Horizon
R Horizon
Soil, Rocks & Minerals
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© Stephanie Elkowitz
O Horizon
A Horizon
O Horizon
B Horizon
A Horizon
B Horizon
C Horizon
C Horizon
R Horizon
Soil, Rocks & Minerals
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© Stephanie Elkowitz
• The very top layer of soil
is called the O horizon.
• This layer is mostly made
of leaf litter and
decomposed organic
matter. We call the
decomposed organic
matter humus.
• For this reason, the
O horizon is also called
humus.
Soil, Rocks & Minerals
O Horizon
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© Stephanie Elkowitz
• The second layer is called
the A horizon or topsoil.
• When we talk about soil
types, we often are referring
to the soil in this layer.
• This layer is made of mineral
and rock particles mixed with
humus.
• This is the primary layer
where plants grow and
animals live.
Soil, Rocks & Minerals
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A Horizon
© Stephanie Elkowitz
• The third layer is called the
B horizon or subsoil.
• This layer is mostly made of
clay and mineral deposits.
• When water drains through
the topsoil, it carries
minerals with it. When the
water moves through the
subsoil, the minerals are
left behind. This process is
called leaching.
Soil, Rocks & Minerals
B Horizon
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© Stephanie Elkowitz
• Sometimes a lightcolored region of soil
forms at the bottom of
the A horizon. This is
where minerals are
“picked up” and carried
to the subsoil. Some
texts assign this lightcolored region as a
separate horizon called
Horizon E.
Soil, Rocks & Minerals
A Horizon
B Horizon
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© Stephanie Elkowitz
• The fourth layer is called the
C Horizon.
• This layer is made of slightly
broken up or weathered
rock.
• The rock in this layer is
considered to be the parent
material to soil. There is no
organic matter in this layer.
Soil, Rocks & Minerals
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C Horizon
© Stephanie Elkowitz
• The bottom layer is called the
R horizon or bedrock.
• Bedrock is solid rock. Over
time, bedrock will weather or
break down, forming the nonorganic (inorganic) particles
that make up soil.
• Some text do not include
bedrock as part of soil but
we will consider it because it
is important to the formation
of soil.
Soil, Rocks & Minerals
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R Horizon
© Stephanie Elkowitz
• Images obtained from commons.wikimedia.org courtesy:
wilson44691, wpsopo, Malene Thyssen, Lyokoi88, En-casede-solei, michael linnenbach, Jarek Tuszynski, Luid Miguel
Bugallo, Mikenorton, luca galuzzi, phillip halling, slim sepp,
Matthew hatten, wilson biggs
• Other images obtained from the Public Domain
• Clipart by:
– Stephanie Elkowitz
– www.mycutegraphics.com
– www.mysweetclipart.com
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© Stephanie Elkowitz