Soil: It aint just Dirt the world is 7inches from starvation

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Soil It aint just Dirtthe world is 7inches
from starvation
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Soil is a complex interface between
the Lithosphere Biosphere Atmosphere Hydrosphere
The sum is greater than the whole of the
parts. One of the most important resources on
the planet...
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Global Soil Orders
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Identifying Soils

• Every soil has unique characteristics... These
  unique features are used to classify soil into
  different orders/groups/types
• The soil profile
• Color
• Structure
• Texture
• pH

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The view from the side the soil profile
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Bama soils the state soil of Alabama
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Mollisols Soft dark soils of grasslands Note the
layer of calcium compounds deposited in the lower
horizion.
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Taxonomy

• Soil types/classification and mapping
• A number of very different classification
  schemes, national scale are all different
• The Russian system is very good but difficult to
  translate (they are often considered to be among
  the first and best soil scientists in the world)
• The NRCS system is optimized for the US and used
  globally order , suborder, great group, sub
  group, family, series

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Every county in the US has been mapped and
described and for each and every county there is
a published soil survey.
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Individual maps are created on black and white
orthophotography. Soil types are identified by a
combination of field work and air photo
interpretation.
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Soil Color is often used as a diagnostic tool to
identify soils.

• The munsell color chart is the common standard,
  it uses hue and chroma values to identify colors.

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Soil texture by feel

• Sandy soils are gritty
• Silt soils are smooth overall it feels like
  flour.
• Clay soils when dry are extremely hard and when
  wet are plastic and sticky.
• Note the significant influence of clay on the
  texture triangle a little goes a long way

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Soil Structure how the individual particles
(sand, silt, clay) are bound together the base
unit is a ped
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The pH scale Critical for plant growth as
nutrients must be not only present in the soil
but available. Soils with extreme pH are not
considered suitable for most plant growth Soils
in humid environments are acidic (pH less than 7)
due to the transport of Ca ions Treatment with
ground limestone (CaCO3)
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Soil Genesis Climate, vegetation, substrate,
topographic setting and time
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Extensive Soil Erosion is very common in all
agricultural areas (NRCS Photos)
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Rill Erosion (NRCS Photo)
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Loess windblown silts
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UN photos
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Plant-Soil relationships Macro Nutrients Micro
Nutrients (Foth, Fundamentals of Soil Science)
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CEC Cation Exchange Capacity a measure of soil
fertility
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(Foth, Fundamentals of Soil Science)
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Soil porosity and root development
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Relationship between soil texture elements and
water holding capacity
(Foth, Fundamentals of Soil Science)
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Bio turbiditation Mixing of soil
layers/particles by organisms
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"I doubt there are many other animals which have
played so important a part in the history of the
world." Charles Darwin
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• English naturalist, Gilbert White (1775)
• Worms seem to be the great promoters of
  vegetation, perforating and loosening the soil,
  rendering it pervious to rains and the fibers of
  plants by drawing straws and stalks of leaves and
  twigs into it and, most of all, by throwing up
  such infinite numbers of lumps of earth called
  worm-casts, which being their excrement, is a
  fine manure for grain and grass. . . . The earth
  without worms would soon become cold, hard-bound,
  and void of fermentation, and consequently
  sterile.

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• André Voisin
• the earthworm, most common in the United States
  and Europe, is not only essential to good
  agriculture but is the very foundation of all
  civilization.
• In Better Grassland Sward, Voisin traces man's
  civilizations in relation to the distribution of
  active earthworms

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Soil is aliveall across the spectrum of living
organisms bacteria, fungi etc.
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Soil forming regimes the environmental settings
for soil genesis pedogenesis

• Based broadly on climatic characteristics
• These are not the soil types we will look at
  next, these are descriptions of the general
  types/ and conditions of formation.

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Laterization (latin laterbrick lateritic soils
are brick red)

• Tropical climate
• Rapid weathering
• Rapid decomposition of OM
• Leaching of Silicaprimary constituents Fe and Al
  oxides
• Little humus accumulation
• Tightly packed clay peds act more like sand than
  clay
• Very poor agricultural soils

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Podzolization (Russian podzollike ashes gray
soils)

• Form under boreal forest Northern hemisphere
• Cold, acidic, heavily leached soils
• Weathered from crystalline rocks with very few
  available cations
• Soil litter from conifers breaks down very
  slowly.. little humus
• Upper horizions appear bleached
• Poor infertile soils

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Gleization (Polish glejmuddy ground)

• Restricted to waterlogged areas
• Dark organic A horizon
• Decay is inhibited by anaerobic conditions
• Very acidic
• Sub-soil can be heavily clay and show mottling
  (dark and light patches that are an indication of
  flooding)

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Salinization (salty soils latin salinsalt)

• Low precipitation
• Moisture drawn upward by capillary action
  (response to rapid evaporation) deposits salts in
  or on the soil surface.
• White salt deposits.
• Can be caused by irrigation, also can be cured
  with irrigation and drainage

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Calcification

• Where PET gt Ppt
• Buildup of CaCO3 in subsoil
• Leaching is restricted
• Grassland soils
• Extremely productive soils

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Soil Ordershttp//soils.ag.uidaho.edu/soilorders/
orders.htm

• the most basic division of soil types
• Gelisols   
• Histosols   
• Spodosols    
• Andisols    
• Oxisols   
• Vertisols   
• Aridisols  
•  Ultisols   
• Mollisols   
• Alfisols  
•   Inceptisols   
•  Entisols

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• Entisols are soils of recent origin.
• Soils developed in unconsolidated parent
  material with no horizons except an A
• All soils that do not fit into one of the other
  11 orders are Entisols
• Inceptisols are soils that exhibit minimal
  horizon development. They
• are more developed than Entisols, but still
  lack the features that are
• characteristic of other soil orders.
• Inceptisols are widely distributed and occur
  under a wide range of
• ecological settings. They are often found on
  fairly steep slopes, young
• geomorphic surfaces, and on resistant parent
  materials
• Vertisols are clay-rich soils that shrink and
  swell with changes in moisture content.
• The soil volume expands considerably as it
  saturates, creating serious engineering problems.
  Because of the shrink/swell activity of these
  soils, they generally do not have distinct,
  well-developed horizons

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• Gelisols are soils of very cold climates that
  contain permafrost within 2 meters of the
  surface. The lack of significant microbial
  activity in these soils leads to an accumulation
  of organic matter over time.
• Histosols are soils that are composed mainly of
  organic materials. They contain at least 20-30
  organic matter. Histosols typically form in
  settings where poor drainage inhibits the
  decomposition of plant and animal remains,
  allowing these organic materials to accumulate
  over time.
• Spodosols are acid soils characterized by a
  subsurface accumulation of humus and Al Fe
  oxides. Spodosols often occur under coniferous
  forest in cool, moist climates.
• Andisols are soils that have formed in volcanic
  ash or other volcanic ejecta.
• Oxisols are very highly weathered soils that are
  found primarily in the tropical regions of the
  world. These soils contain few available cations
  and are often rich in Fe and Al oxide minerals

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• Aridisols are CaCO3-containing soils of arid
  regions that exhibit at least some subsurface
  horizon development. They are characterized by
  being dry most of the year. Aridisols contain
  subsurface horizons in which clays, calcium
  carbonate, silica, salts, and/or gypsum have
  accumulated.
• Ultisols are strongly leached, acid forest soils
  with relatively low native fertility. They are
  found in humid temperate and tropical areas of
  the world, typically on older, stable landscapes.
  Ultisols have a subsurface horizon in which clays
  have accumulated, often with strong yellowish or
  reddish color due to the presence of Fe oxides,
  such as in the 'red clay' soils of the
  southeastern United States.
• Mollisols are the soils of grassland ecosystems.
  They are characterized by a thick, dark surface
  horizon. Calcium carbonate in the subsoil is
  derived from the lime-rich parent material.
  These minerals dissolve in the upper profile
  where the moisture content is greater, leach
  downward, and precipitate in the lower profile
• Alfisols are moderately leached forest soils
  that have relatively high native fertility. These
  soils are well developed and contain a subsurface
  horizon in which clays have accumulated.

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