Transcript Soil

 The
loose, weathered material
on Earth’s surface in which
plants can grow.
 The
main ingredient for soil is
the solid layer of rock
beneath the soil called
bedrock.
A
mixture of rock
particles, minerals,
decayed organic
materials, water and air.
 Known as sand, silt, clay
and gravel
 Decayed
organic material in
soil from plant and animal
remains
 Provides spaces in soil for
water and air
 Also contains many nutrients
that plants need to grow
 Often dark in color
 The
measure of how well soil supports
plant growth
 Soil rich in humus has a high fertility
content
 Sandy soil has low humus and a low
fertility content
 Depends
on the size of soil particles
 Sand feels coarse and grainy
 Clay feels smooth and silky
 Silt is dry or moist and sticky
 Classified by size (smallest to largest)
• Clay
• Silt
• Sand
• Gravel
 Soil
that is made of equal
parts clay, silt and sand
and holds air and water
 Soil
forms as rock is broken down
by weathering and mixes with
other materials on the surface
 Soil is constantly being formed
whenever bedrock is being
exposed
 Soil forms into horizons or layers
A
layer of soil that differs in
color and texture from the layers
above and below it
 Horizon
A- topsoil- a crumbly, dark
brown soil with a mixture of humus,
clay, and other materials
 Horizon B – subsoil- clay and other
particles washed down from A, little
humus
 Horizon C – weathered rock
Horizon A Topsoil
Horizon B Subsoil
Horizon C
Bedrock
 These
living things make
humus and other materials that
makes soil fertile
 These creatures mix the soil
and make spaces for water and
air
 The
loose layer of dead plant
leaves and stems on the soil
surface
 Organisms
that live in soil and turn dead
organic material into humus
 Includes fungi, bacteria, worms and other
small animals or bugs
 Worms do most of the work, they eat their
way through the soil and carry soil
between layers, the waste is enriched
with nutrients