Download Chapter One

The Importance of Soil
Original by Nancy Williams
Modified by Georgia Agricultural
Education Curriculum Office
July, 2002
August 2008
The Importance of Soil
• The history of soil
– Dates back all the way to the Egyptians
civilization of 4,000 years ago
– Recently in the US history supplies another
example of soil misuse. This is with the Dust
bowl of the 1930’s.
– The Dust bowl was a drought that misused
the soil in having wind erosion.
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The Importance of Soil
• Additional acreage is lost due to
urbanization or degradation .
• Soil is a nonrenewable resource
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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.
August 2008
The Importance of Soil
• Facts about the earth
– Earth consists of solid part (core, mantle, and
crust) and the atmosphere surrounding it.
– Most of the earth is covered by sea
– Where continents exist the crust is thicker
– This is usually about 50 miles thick
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The Importance of Soil
• The atmosphere is about 170 miles deep.
• The soil forms a very thin interface
between the two.
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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
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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
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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
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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
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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
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The Importance of Soil
• Nitrogen:
– Comes directly from the atmosphere where it
occurs as a gas that plants cannot use.
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4 Needs of Soil
• There are four needs of the soil
– Anchorage
– Water
– Oxygen
– Nutrients
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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 .
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4 Needs of Soil
• Oxygen:
– Call creature even plants need oxygen. Plants
release oxygen during photosynthesis but
consume it during respiration.
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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
August 2008
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.
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3 phase system
• The ideal Soil Type:
– 50% solid material
– 45 % mineral particles
– 5% organic matter
– 25% water
– 25% gases
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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
August 2008
Ag Uses of Soil
• Humans depend on soil to grow food,
fiber, timber, and ornamental plants.
• Most Ag uses require different soil types
and management practices
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4 Types of Ag Uses
• 1. Cropland:
– Cropland is land which soil is worked and
crops are planted, cared for, and harvested.
– Crops that are grown
• Annual crops are corn and soybeans
• Fiber crops are cotton horticultural crops like
vegetables.
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4 Types of Ag Uses
• Annual Crops:
– Require yearly soil preparation
– Perennial Forages:
– Are alfalfa.
– Which are crops that are in the ground for a few
years
– These crops keeps the soil completely cover and
keeps the soil in place.
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4 Types of Ag Uses
• Perennial Hort. crops:
– This includes fruits,
nuts, and nursery
stock
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4 Types of Ag Uses
• 2. Grazing Land:
– Much of the land in the US is grazed by cattle
and sheep
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4 Types of Ag Uses
• 3. Forest
– Foresters probably disturb soil the least,
– 4.
Other Uses
– This usually deals with growing plants in tiny pots
and usually with Landscapers
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Non Ag Uses of Soil
• A few of the Non Ag uses of soil are:
– Recreation
– Foundations
– Waste Disposal
– Building Materials
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Non Ag Uses of Soil
• Recreation:
– Recreational uses of the soil can be:
• Sitting in a urban park and seeing kids play on the
playground, softball diamond,
• They can also be golf courses, campgrounds.
• Most demanding recreational use is the use of
playing fields. As most of the time there is a
demand to have good grow on turf that can with
stand about anything.
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Non Ag Uses of Soil
• Foundations:
– A good builder usually will have the soil
tested to a dept of several feet.
– The structural soundness of a building
depends on the amount of soil that is under
the building.
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Land Uses in the US
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27% is in rangeland
26% is in cropland
27% is in forestland
2% is in conservation reserve land
4% is in other land
6% is in urban land
8% is in pastureland
August 2008