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

2 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 don’t hold water! Soil reaction – acid or base, leached or not leached, saturated or not saturated

3 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.

4 Pop Quiz Question: Direction of water flow?

5 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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9 Soil Color Coloring agents in the soilEffect/expression of Organic matterdarkens 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 colorthe dominant color in the soil Mottlingspots or blotches of color in the soil that differ from the matrix color Redoximorphic featuresmottles that relate to the aeration, drainage, and alterations between aerobic and anaerobic of the soil

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

11 ABC D Deal or No Deal! As a generalization – soils of fine, very uniform texture and very limited particle size distribution often have ‘internal drainage’ limitations.

12 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

13 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

14 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 > evapotranspiration there is leaching of sequioxides, carbonates, and silicate clays. The elluviated horizon consists mainly of silica

15 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.

16 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

17 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.

18 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.

19 Yellow to reddish Fe 3+ (oxidized iron) Well-aerated soils Gray, bluish- green Fe 2+ (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 -

20 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.

21 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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23 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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27 Questions