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Essential Question
What
is Soil?
Add to table of contents:
Soil Horizons
Soil
Pg. 68
Pg. 69
Observing Soil - What do you
see?
Soil
Soil
Pg. 69
is a mixture of four materials:
Soil
Soil
Pg. 69
is a mixture of four materials:
Weathered
rock particles
Soil
Soil
Pg. 69
is a mixture of four materials:
Weathered
rock particles
Organic matter
Soil
Soil
Pg. 69
is a mixture of four materials:
Weathered
rock particles
Organic matter
Water
Soil
Soil
Pg. 69
is a mixture of four materials:
Weathered
rock particles
Organic matter
Water
 Air
Humus: The decayed organic matter in
soil.
Humus: The decayed organic matter in
soil.
(Organic matter comes from the
remains and waste products of plants,
animals and other living things.)
Factors that form soil:
Factors that form soil:
Kind of rock.
Factors that form soil:
Kind of rock.
The area’s climate.
Factors that form soil:
Kind of rock.
The area’s climate.
Landforms in the area.
.
Factors that form soil:
Kind of rock.
The area’s climate.
Landforms in the area.
Plant cover and animals in the area.
Factors that form soil:
Kind of rock.
The area’s climate.
Landforms in the area.
Plant cover and animals in the area.
Time.
Soil Horizon: A layer of soil
with properties different
from the layers above and
below it.
Horizon O - organic-mostly dead plant matter.
Horizon O - organic-mostly dead plant matter.
Horizon A - Topsoil. Contains the most organic
matter (humus) and is dark in color.
Horizon O - organic-mostly dead plant matter.
Horizon A - Topsoil. Contains the most organic
matter (humus) and is dark in color.
Horizon B - Subsoil. The layer under A that
contains clay and minerals and is usually
brownish or reddish in color.
Soil Horizons
Horizon C - The deepest layer of soil.
Contains the largest and least weathered
rocks. It is usually yellowish brown.
Soil Horizons
Horizon C - The deepest layer of soil.
Contains the largest and least weathered
rocks. It is usually yellowish brown.
Horizon D – Bedrock below soil.
How do organisms effect soil?
Plants – add organic matter or humus to the soil.
Microorganisms – decomposers(bacteria and
fungi) decompose dead organisms and return
nitrogen to the soil.
Animals - loosen and mix the soil(as they build
their homes) which adds air to the soil. They
also add humus when they die.
Soil Horizons Pg. 68
Attach to page 68 and color
and label each soil horizon.