Soil: The Foundation of Living Things

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Soil The Foundation of Living Things!
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What is Soil?

• Soil A mixture of weathered particles of rock
  and organic matter containing moisture and air
  and capable of supporting plant life.
• It takes about 100 years for the earth to form 1
  of soil
• Most living things depend on the top 18 of top
  soil.

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Soil is NOT Dirt!!!

• Dirt is not capable of sustaining plant life.
• Dirt is either dust or mud

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Physical Characteristics of Soil

• Volume- soil is made up of two basic parts
• Pore Space
• Solid Material
• Solid material consists of
• Rock or mineral matter
• Organic matter

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Physical Characteristics of Soil

• Soil Texture- the size of the individual soil
  particles. Can be determined by sight and touch.
• Soil Texture cannot be changed
• Sand- largest particle size (Coarse)
• Silt- (medium texture)
• Clay- smallest particle size (Fine Texture)

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Sand - review

• Sand
• Largest soil particle
• Often have problems holding enough water to
  support plant growth
• Individual particles can be seen with the naked
  eye

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Silt - review

• Silt
• Intermediate Soil particles but can not be seen
  with the naked eye

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Clay - review

• Clay
• The smallest soil particles
• Holds water
• May be airtight, infertile or overly wet

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Physical Characteristics of the Soil

• In two tablespoons of soil there are
• 5,774 parts sand
• 5,776,674 parts silt
• 90,260,853,860 parts clay!!

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Physical Characteristics of Soil

• Soil Structure the way the individual soil
  particles stick together (aggregate) while
  leaving pore space to store air, water,
  nutrients, and allow for root penetration
• Blocky typically clay
• Granular most desirable
• Single Grains sandy soils

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Soil Profile
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Soil Horizons

• O
• Organic
• Black or dark brown
• Loose, crumbly, well broken up
• Decomposition

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Soil Horizon

• A
• Topsoil
• Dark brown to yellow
• Generally loose, crumbly, well broken up
• Considered the surface layer when evaluating soil

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Soil Horizon

• B
• Subsoil
• Generally larger chunks, may be dense or crumbly,
  
• Subsurface level for evaluation
• Most have an increased clay content

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Soil Horizon

• C
• Parent material
• Bedrock
• Loose to dense

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Soil Profile
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Soil Profile
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Soil in Environmental Science
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Land classification

• Land capability maps are based on the physical,
  chemical, and topographical aspects of the land

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Land classifications

• Are designated by Roman Numerals

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Land Classifications

• Class I - II land is the best for the most
  intensive cultivation of field crops. Can
  usually be planted year after year.
• Worth a lot of money!!

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Land Classifications

• Class III - moderately good land
• crops must be more carefully selected
• often gently sloping hills
• Class IV - fairly good land
• lowest class cultivated
• on hills with more slope than class III

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Land Classifications

• Class V and VI- Pasture land or hay production.

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Land Classification

• Class VII- Limited grazing or forestry. Is very
  steeply sloped and is best used for planting trees

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Land Classification

• Class VIII- Wildlife and recreation

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Effects of Soil Structure on Plant Growth

• 1. Development of the plant root system.

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Effects of Soil Structure on Plant Growth

• 2. Water supply
• Clays will hold more water
• Sandy soil drains faster

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Effects of Soil Structure on Plant Growth

• 3. Air Supply
• Plant roots need air
• Clay holds less air than sand

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Effects of Soil Structure on Plant Growth

• 4. Formation of crust and emergence of
  seedlings.
• Clay tends to be crustier
• Seedlings can break through easier in sandy soil

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Conservation Farming

• Three types of erosion
• Sheet
• Gully
• Wind

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Conservation Farming

• Erosion
• The displacement of soil by wind, water or gravity

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Conservation Farming

• Contour farming- farming with the lay of the
  land.
• Conserves soil and slows down erosion

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Conservation Farming

• Strip Cropping- Rotating strips of close growing
  crops and row crops.

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Soil conservation and enhancement

• No-till is a cropping technique used to reduce
  soil erosion
• Crops are planted directly into the residue of a
  previous crop without plowing or disking
• Very effective erosion control

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Soil conservation and enhancement

• Conventional tillage- uses tillage system that
  disturbs the soil surface by plowing and/or
  harrowing

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Soil Conservation

• Conservation tillage- intermediate tillage system
  between conventional and no-till

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What is Soil pH? - REVIEW

• pH a numerical value between 0 and 14 used to
  indicate the degree of acidity or alkalinity.

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REVIEW

• Most plants grow between 4.8 and 6.5 (slightly
  acidic)
• Most soil in this area that is not altered is 5.5
  pH

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Changing Soil pH - REVIEW

• Use lime as an amendment to raise soil pH
• Increases availability of nutrients
• Example if soil pH is 5.5, lime may be added to
  raise soil pH to a more acceptable 6.8 level

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Changing pH Review - REVIEW

• Lime is Calcium (Ca)
• Source of Calcium and Magnesium
• What will you use if pH is to High?
• Sulfur