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Chapter 12: Soils

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Title: Chapter 12: Soils


1
Chapter 12 Soils
2
Outline
  • Soil and Regolith
  • Soil Forming Factors
  • Soil Components
  • Soil Properties
  • Soil Chemistry
  • Soil Profile
  • Soil Classification
  • Global Distribution of major soils
  • Distribution of Soils in the United Sates
  • Earthworms in Soil
  • Forms of soil Moisture

3
Soil and Regolith
  • Soil Thin layer of mineral matter that normally
    contains a considerable amount of organic matter.
    Soil is capable of supporting living plants
  • a.     topmost layer of the lithosphere
  • b.     average worldwide depth of 6
  • Soil Development Depends on Weathering/
    Denudation.
  • Regolith Layer of broken and partly decomposed
    rock particles that cover the bed rock

4
Soil Forming Factors
  • Geologic Factors
  • Parent Material and chemical composition
  • II The climatic Factors
  • Temperature and moisture
  • III Topographic Factors
  • Slope and Drainage
  • IV Biological Factors
  • V The chronological factors

5
Soil Components
  • Organic Matter
  • Sand
  • Silt
  • Clay
  • Soil water
  • Solvent
  • Leaching
  • Soil Air
  • Percolation
  • Capillary rise
  • Pore space/Interstices

6
Soil Water Balance
  • Gain, loss and storage
  • Available Filed capacity-wilting point
  • Soil water budget is variable with time
  • In midlat Northern Hemisphere
  • January surplus
  • Spring temperature rise, more ET, plant growth
  • Summer soil moisture deficit
  • Fall temperature decreases and growth slackens

7
Soil Properties
  • Color
  • Texture
  • Structure Spheroidal, platy blocky, prismatic
  • Soil chemistry
  • Colloids lt .1 micron
  • Colloids are chemically active
  • Cation Exchange Capacity
  • Acidity/Alkalinity
  • Neutral good

8
Earth Worms in Soil
  • 7 Beneficial functions
  • Drainage
  • Soil structure improvement
  • Bring material to surface for weathering
  • Leaf litter carried down their hole
  • Increase porosity
  • Increases nutrients in soil
  • Promote nitrification
  • Productivity increases
  • Thrive in humid and temperate reasons
  • Sheep weight in NZ earthworms weight

9
Forms of Soil Moisture
  • Gravitational water
  • Capillary water
  • Hygroscopic water
  • Combined water
  • Practical significance

10
Soil Horizons
  • O
  • A
  • E
  • B
  • C
  • R
  • Solum upto B horizon
  • Mature ABC
  • Immature A and C

11
Pedogenic Regimes
  • Laterization soil forming regime
  • Laterization (temperature dominant factor
  • Pedzolization (long cold winter)
  • Gleizatioon (saturated soils
  • Calcification ( upward soil moisture movement)
  • Salinization

12
Soil Classification
  • 12 soil orders distinguished by diagnostic
    horizon
  • Entisols (little profile development)
  • Inceptisols (few diagnostic horizons)
  • Andisols (volcanic)
  • Gelisols (freezing and Thawing)
  • Histosols (organic)
  • Aridisols (dry soils)
  • Vertisols (clay)
  • Mollisols (Dark soft grassland soils)
  • Alfisols ( clay accumulation with high bases)
  • Altisols ( Clay accumulation with low bases)
  • Spodosols (acidic sandy forest soils)
  • Oxisols (highly weathered and leached

13
How to prepare for finals
  • Final May 14 Thursday 930 AM
  • There will be no make up for the final
  • There will be
  • True false questions
  • Fill in the blanks
  • Multiple choice
  • Short answers
  • Final covers chapters
  • 1 through 10
  • Read all assignments
  • Go through all homewroks
  • Read all quizzes
  • Read all figure in the chapters
  • Read all handouts
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