Important/significant foundation soil physical properties

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Important/significant foundation soil physical
properties
Color Redoximorphic features Texture
Structure Consistence Coarse fragments Reaction
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Important/significant foundation soil physical
properties

• Color not an influence, but an indicator and
  diagnostic resource
• Texture the composition (sand, silt, clay), the
  feel, the classification (triangle) - micropores
• Structure how the particles are aggregated,
  bound together macropores
• Consistence how the soil holds together, feels,
  can be worked when wet assessing texture
• Coarse fragments rocks dont hold water!
• Soil reaction acid or base, leached or not
  leached, saturated or not saturated

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• Color reflects physical, chemical and/or
  biological composition and processes
• Dark brown-black organic matter
• Bright-light leached or bleached zones
• Subsoil color reflects parent material
• Subsoil color reflects redox status
• oxidation aerated
• reduction anaerobic, lacking oxygen
• Carbonates, sulfates, chlorides affect color
• Mottles, speckles, blotches alternating wet and
  dry conditions.

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Pop Quiz Question Direction of water flow?
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Soil color as a diagnostic tool Color reflects
the parent material, the soil formation process,
and the hydraulic properties of the soil

• There are two ways to look at soil color
• 1) as a diagnostic tool what happened!
• 2) as a characterization/classification tool
  what will happen!

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Soil Color
Coloring agents in the soil Effect/expression of
Organic matter darkens the soil
Iron (Fe)primary coloring agent in the subsoil orange brown colors associated with well drained soils are the result of Fe oxide stains coating individual particles.
Manganese (Mn) is common in some soils very dark black or purplish black color
Matrix color the dominant color in the soil
Mottling spots or blotches of color in the soil that differ from the matrix color
Redoximorphic features mottles that relate to the aeration, drainage, and alterations between aerobic and anaerobic of the soil
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mottles that relate to the aeration and drainage
status of the soil, and alterations between
aerobic and anaerobic conditions of the soil
Redoximorphic features
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D
A
B
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Deal or No Deal!
As a generalization soils of fine, very uniform
texture and very limited particle size
distribution often have internal drainage
limitations.
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Alisol poorly drained clay loam soil due to
dense sub-surface horizon rich in clay and
aluminum
Poorly drained silty clay loam derived from
alluvial deposits on a modern-day flood plain
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Deep, poorly drained fine sandy loam formed
in sandy marine deposits, flood-plains and
depressions. Shallow water table
Moderately well drained, slow permeability, deep
to water table. Smectite clay high shrink-swell
properties
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Soil colors associated with soil attributes.
Soil color Soil attributes Environmental conditions
Brown to black (surface horizon) accumulation of organic matter (OM), humus low temperature, high annual precipitation amounts, soils high in soil moisture, and/or litter from coniferous trees favor an accumulation of OM
Black (subsurface horizon) Accumulation of manganese Parent material (e.g. basalt) -
Bright-light- nearly white Elluvial horizon (E horizon) In environments where precipitation gt evapotranspiration there is leaching of sequioxides, carbonates, and silicate clays. The elluviated horizon consists mainly of silica

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Brown to black (surface horizon) surface
well-drained, good aeration. Darker vertical soil
deposits are remnants of burrowing animals. The
technical term is krotovina (crotovina) an
animal burrow that has been filled with organic
or mineral material from another soil horizon.
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Reddish brown subsoil, suggesting good drainage,
aeration. Note the buried A horizon, with
additional subsoil material above suggesting
colluvial deposition or some form of mass action
in recent past. Zone of elluviation below the
buried A horizon
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Bright-light eluvial zone below the relatively
shallow organic horizon near surface the
light- colored soils, the abundance of red and
yellow suggest a well-drained soil. Consider- ing
that elluviation has also occurred, one would
conclude that this would be a suitable site
good internal drainage, appears to have good
water holding capacity.
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Redox reduction-oxidation status

• Reduction oxygen is depleted from the soil, the
  soil may be anaerobic, iron and manganese
  chemistry change, resulting in color changes.
• Mottles/Gleying
• Oxidation oxygen is present in the soil, the
  soil is aerobic, leaching is likely occurring,
  light color of soil.

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Yellow to reddish Fe3 (oxidized iron) Well-aerated soils
Gray, bluish-green Fe2 (reduced iron) Poorly drained soils (e.g. subsurface layer with a high bulk density causes waterlogging, or a very fine textured soil where permeability is very low), anaerobic environmental conditions
White to gray Accumulation of salts In arid or subhumid environments where the evapotranspiration gt precipitation there is an upward movement of water and soluble salts in the soil
White to gray Parent material marl, quartz -
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An explanation of the Munsell color wheel and
Munsell color charts
Hue It is the dominant spectral color, i.e.,
whether the hue is pure color such as yellow,
red, green, or a mixture of pure colors. Value
It describes the degree of lightness or
brightness of the hue reflected in the property
of the gray color that is being added to the
hue. Chroma It is the amount of a particular
hue added to a gray or the relative purity of the
hue.
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Standardizing Color the Munsell Color Chart

• Munsell Color System
• Hue refers to the dominant wavelength of light
  (color) (red, yellow, green, etc.).
• Value refers to the lightness and darkness of a
  color in relation to a neutral gray scale.
• Chroma is the relative purity or strength of the
  Hue.
• Notation

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Hue 5YR Value 2.5 8 Chroma 1-8 So, for
example a soil horizon with a Munsell color
description of 5YR 5/4
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Questions