Important/significant foundation soil physical properties

Color

Redoximorphic features

Texture

Structure

Consistence

Coarse fragments

Reaction

Important/significant foundation soil physical properties

Color not an influence, but an indicator and diagnostic resourceTexture the composition (sand, silt, clay), the feel, the classification (triangle) - microporesStructure how the particles are aggregated, bound together macroporesConsistence how the soil holds together, feels, can be worked when wet; assessing textureCoarse fragments rocks dont hold water!Soil reaction acid or base, leached or not leached, saturated or not saturated

Color reflects physical, chemical and/or biological composition and processesDark brown-black = organic matterBright-light = leached or bleached zonesSubsoil color reflects parent materialSubsoil color reflects redox status

oxidation = aerated

reduction = anaerobic, lacking oxygen

Carbonates, sulfates, chlorides affect color

Mottles, speckles, blotches alternating wet and dry conditions.

Pop Quiz Question: Direction of water flow?

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 soilEffect/expression ofOrganic matterdarkens the soilIron (Fe):primary coloring agent in the subsoilorange brown colors associated with well drained soils are the result of Fe oxide stains coating individual particles.Manganese (Mn) is common in some soilsvery dark black or purplish black colorMatrix colorthe dominant color in the soilMottlingspots or blotches of color in the soil that differ from the matrix colorRedoximorphic featuresmottles that relate to the aeration, drainage, and alterations between aerobic and anaerobic of the soil

Redoximorphic features

mottles that relate to the aeration and drainage status of the soil, and alterations between aerobic and anaerobic conditions of the soil

XTRA SLIDES

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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.

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

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

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 manganeseParent material (e.g. basalt) - Bright-light- nearly whiteElluvial horizon (E horizon) In environments where precipitation > evapotranspiration there is leaching of sequioxides, carbonates, and silicate clays. The elluviated horizon consists mainly of silica

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.

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

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.

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/GleyingOxidation oxygen is present in the soil, the soil is aerobic, leaching is likely occurring, light color of soil.

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 > precipitation there is an upward movement of water and soluble salts in the soil White to gray Parent material: marl, quartz -

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.

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

Hue = 5YR

Value = 2.5 8

Chroma = 1-8

So, for example: a soil horizon with a Munsell color description of 5YR 5/4 =

Questions