Download Lesson 2 – Soil

Don’t SOIL
yourself…
Some Soil
Yep, that’s some more soil
Soil Creation
• Soil is the top layer of the earth’s crust that
has been physically and chemically
weathered into small particles
Soil-forming processes
• Decaying vegetation in humus
– Organic matter is broken down to form a dark,
sticky, partly decomposed layer at the soil
surface.
– Soil high in humus are generally very fertile
and ideal for agriculture
Soil-forming processes
• Leaching
– As water infiltrates the soil, it carries
dissolved minerals deep into the weathered
particles.
– In areas with a great deal of rainfall, leaching
is excessive and valuable minerals are lost in
the soil.
Soil-forming processes
• Capillary Action
– Occurs in dry desert and grassland areas
where the surface is so dry, that water is
transferred from deep in the ground to the
surface
Soil-forming processes
• Translocation
– The movement of solid material from one
place to another by moving water.
:
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Formation of Soil Profiles
• physical and chemical weathering from parent
material
• -broken material and organic matter (vegetation)
• -profiles are soil layers developed in different
climates
• -horizons are the layers that form due to water
and vegetation presence
TOPSOIL,
upper or A
horizon
SUBSOIL,
middle or B
horizon
PARENT
MATERIAL,
lower or C horizon
Horizons:
A horizon: is the topsoil layer
-darker it is, the more humus
-lots of humus is healthy, fertile
soil
B horizon: it the subsoil
-brown or red in colour(Fe)
-more clay than A horizon
-lose fertility quickly
C horizon: partially weathered rock
-rocky and fractured
Bedrock: parent material
1. Chernozem
2. Podzol
3. Laterite
4. Sierozem
5. Tundra
Chernozem Soils
-prairie grasslands
-thick-humus filled
topsoil
-leaching is not a
problem
-capillary action brings
nutrients to surface
-small animals burrow
to keep warm and mix
soil
Podzol
Podzol Soils
-formed in coniferous
forests
-humid continental with
cold winters, warm
summers
-heavily leached and
acidic
-thin humus layer of
evergreen needles
-not very fertile
Laterite: -hot, tropical climate, deeply leached, heavy rainfalls, ironoxide concentrations, most infertile soils in the world (nutrients are in the
Sierozem Soils
-desert soils (dry)
-limited vegetation, low
organic content
-poorly defined because
of lack of water
-could be fertile if
irrigated because capillary
action brings nutrients to
surface
Tundra Soil, peeled back to show layer
Tundra Soils:
-permafrost below surface
-not well defined profile
-vegetation cover is limited
because of climate
-partially decomposed peat
layer is slow to develop
because of climate
Key Soil Profiles