Soil
The following power point was adapted
from Ryan P. Murphy. A full collection of
his amazing power points can be found at:
http://sciencepowerpoint.com/index.html
SOIL
http://www.youtube.com/watch?v=Uv1btp3E8qk
Weathering is the process that will, overtime,
create soil.
Soil is a mixture of weathered rock and decaying
organic material.
Soil Formation
•Soil is formed as rock is broken down by weathering and is mixed wit
other materials on the surface by burrowing animals.
•Soil is constantly being formed wherever bedrock is exposed.
•Bedrock is the solid layer of rock beneath the soil.
Five Factors That Affect Soil Formation
1. Climate: temperature
and rainfall
2. Plants and animals
3. Topography: flat lands
are more fertile than
hilly lands
4. Parent material
5. Time: more time =
healthier soil
Four Steps To Soil Formation
1. Bedrock disintegrates
Four Steps To Soil Formation
1. Bedrock disintegrates
2. Parent material forms
Four Steps To Soil Formation
1. Bedrock disintegrates
2. Parent material forms
3. Organic matter collects forming humus
Four Steps To Soil Formation
1.
2.
3.
4.
Bedrock disintegrates
Parent material forms
Organic matter collects
Thick vegetation grows and gives back to the soil
Soil Composition
•Soil is a mixture of rock
particles, minerals, decayed
organic material, air, and
water.
•The type of rock particles
and minerals depends on the
bedrock that was weathered
and the type of weathering.
•Sand, Silt, and clay make up
the portion of soil that
comes from weathered rock.
Humus
•Decayed, organic material
in soil
•Dark in color
•Forms from decaying
plant and animal material
•Creates spaces in soil for
air and water
•Rich in nutrients that
plants need to grow
Color Of Soil- helps determine what
soil is made of and its health
Black Soil
• Lots of organic matter (carbon)
• May be poorly drained
• Usually fertile
Brown Soil
• Lots of sand and clay
• Well drained
• Good soil
Light brown, white, orange, red,
yellow
• Many compounds
present (iron,
manganese, sulfur)
• High is salt
• Not as healthy
• Iron turn rust color
when it mixes with
oxygen (oxidation)
Particles of Soil
• The type of soil depends on its particles
• The combinations of particle size can
determine how well plants grow in soil
Soil Texture and Particle Size
• Gravel: 2-7.5cm
Soil Texture and Particle Size
• Gravel: 2-7.5cm
• Sand: 2-.125mm
Soil Texture and Particle Size
•
•
•
Gravel: 2-7.5cm
Sand: 2-.125mm
Silt
Soil Texture and Particle Size
•
•
•
•
Gravel: 2-7.5cm
Sand: 2-.125mm
Silt
Clay
Soil Horizons
•Soil Horizon is a layer of
soil that differs in color
and texture from the layers
above or below it.
• O – organic layer (leaves,
pine needles, twigs, decay)
• A – Top Soil: dark color is
from the mixing of humus
with weathered materials
• E – Eluviated zone;
movement of dissolved
materials from A horizon
• B – Sub Soil; Illuviated zone
– contains soil materials
leeched from above
• C – Parent Material;
partially weathered mineral
particles
• D/R - Bedrock
Rate of Soil Formation
•Depends on climate and
type of rock
•Weathering occurs most
rapidly in a warm, rainy,
climate
•Some rocks, like
limestone, weather faster
than other types of rock,
like granite.