Transcript Soil - Earth Science With Mrs. Locke

Soil is
A loose mixture of
small minerals and
rock fragments,
organic material,
water, and air.
What’s in soil?
Soil
• The kind of soil in an area is
determined by:
–Parent rock or
bedrock
–Climate of region
Soil properties
1. Texture (grain size)
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Gravel
Sand
Silt
Clay
Each has advantages
and disadvantages so
its best with a
mixture.
2. Structure- how evenly mixed
the nutrients &textures are
3. Fertility- how much nutrients are
in the soil, how good it is for
growing.
Soil forms very slowly but it will
eventually form layers
Litter
Humus rich
(Topsoil)
Clay & mineral rich
(Subsoil)
Weathered rock
Bed or Parent Rock
Soil is important because:
How soil is made
1. The solid bedrock
is weathered by
acids from water
and living things
mainly into
smaller pieces...
2. Over time this
forms the C
horizon, a layer of
weathered rock.
3. Eventually enough
poor soil builds up
that simple plants
and animals move
into the area.
4. Weathering
continues to
make the rock
fragments
smaller and
smaller
5. As living things
die they add
humus to the
soil.
6. As humus is mixed
with the poor soil the
A horizon forms.
7. Then larger plants
and animals can
move in further
adding to the litter
and humus.
8. Rain water helps the
B horizon separate
out.
The role of organisms and
decomposers
• mix it making room for water and air.
• Make humus from litter (mostly Fungi
Bacteria, and worms)