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Chapter One
The Importance of Soil
Video
The Importance of Soil


Additional acreage
is lost due to
urbanization or
degradation .
Soil is a
nonrenewable
resource
The Importance of Soil


Most of the time we
take soil for
granted.
Soil is a very thin
and often fragile
layer of life
supporting material.
The Importance of Soil

What does living things need?
– Proper temperature
– Oxygen
– Water
– Carbon
– Other nutrients
– These factors are exchanged in the soil
that allow elements to be recycled rather
than lost
The Importance of Soil

Oxygen:
– Plant roots need
oxygen to grow.
– Gases will pass in
and out of the soil to
supply the oxygen
for the roots
The Importance of Soil
– Temperature
 Plants
will grow best in certain soil
temperature ranges.
 Most plants will root in temperature around
40-50 degrees F.
 Water:
– Seldom stays in one place
The Importance of Soil

Carbon:
– Plant leaves collect sunlight to use the
energy in the process of photosynthesis.
– Which involves converting atmosphere
carbon to biological carbon
– Atmosphere carbon = carbon dioxide
– Biological carbon = simple sugars
The Importance of Soil

Nutrients :
– Plant nutrients are
chemicals a plant
needs to grow.
– There are two types
of nutrients cycles


Nitrogen cycle
Mineral cycle
The Importance of Soil

Nitrogen:
– Comes directly from
the atmosphere
where it occurs as a
gas that plants
cannot use.
4 Needs of Soil

There are four needs of the soil
– Anchorage
– Water
– Oxygen
– Nutrients
4 Needs of Soil

Anchorage:
– This is where plants
grow freely and are
firmly supported or
anchored so they
can grow to reach
the sunlight.
– Water:
– Soil will provide the
plants with all the
water the plant
needs
– Roots are the best
water absorbing
body .
4 Needs of Soil

Oxygen:
– All creature even plants need oxygen.
Plants release oxygen during
photosynthesis but consume it during
respiration.
4 Needs of Soil

Nutrients:
– There are 16 nutrients usually considered
to be needed for plants.
– Plants obtain 13 of the 16 nutrients from
the soil itself.
– Other nutrients come from Air and water.
 Carbon
 Oxygen
 hydrogen
3 phase system

What is soil Matrix?
– It is the arrangement of solid particles
and pore spaces which consists of three
phases of solid , liquid, and gases.
3 phase system

The ideal Soil Type:
– 50% solid material
 45
% mineral particles
 5% organic matter
– 25% water
– 25% gases
3 phase system

Root Growth:
– Water reaches the root by two ways
either water flows toward the root
 Or the root grows into moist soil

Soil Particles
Sand: .05-2mm
 Silt: .002-.05 mm
 Clay: <.002 mm

Sand
.05-2mm
 Sand drains easily = POOR ABILITY
TO RETAIN MOISTURE
 Little chemical activity = LITTLE
NUTRIENT BONDING

Silt
.002-.05mm
 Able to hold lots of water and gives
water to plants easily
 Little chemical activity = LITTLE
NUTRIENT BONDING
 May compact under heavy traffic =
poor air and water movement

Clay
<.002mm
 Water adheres very well to clay =
HIGH ABILITY TO RETAIN
MOISTURE

– But can hold water so tightly plants can’t
get it

Very chemically active = GOOD
NUTRIENT BONDING
Soil Texture Ribbon
Test
Used to determine what particles your
soil is made up of
 Loam- a fertile soil of clay and sand
containing humus.
 Ribbon test Video

Soil Texture Triangle
Video