PedologyPedology► Soil morphology: Soil morphology: color, physical structure, color, physical structure,

and chemical and mineralogical properties of and chemical and mineralogical properties of horizonshorizons

► Soil genesis: Soil genesis: processes of soil formationprocesses of soil formation► Soil classification: Soil classification: categorization of soils in categorization of soils in

groups according to their morphological groups according to their morphological properties and/or assumed genesis properties and/or assumed genesis

► Soil survey:Soil survey: determination of type and determination of type and pattern of the occurrence of soil bodies on the pattern of the occurrence of soil bodies on the landscape landscape

► Soil characterization:Soil characterization: determination and determination and quantification of chemical, physical, quantification of chemical, physical, mineralogical, and biological properties of mineralogical, and biological properties of samples collected from soil horizons.samples collected from soil horizons.

► Soil interpretation:Soil interpretation: analysis of soil data to analysis of soil data to infer suitability, potential use, and limitations infer suitability, potential use, and limitations for various uses.for various uses.

Concepts and Definitions of SoilConcepts and Definitions of Soil► Soil has been defined by many groups Soil has been defined by many groups

in a variety of ways. in a variety of ways. GeologyGeology Engineering Engineering Plant productivityPlant productivity ““Natural body”Natural body”

► Pedological definition - the collection of Pedological definition - the collection of natural bodies on the earth's surface natural bodies on the earth's surface containing living matter and supporting containing living matter and supporting or capable of supporting plants out-of-or capable of supporting plants out-of-doors.doors."each soil has a unique morphology resulting "each soil has a unique morphology resulting

from the combination of climate, living from the combination of climate, living matter, and relief acting upon earthy parent matter, and relief acting upon earthy parent materials over time."materials over time."

Miller’s definitionMiller’s definition

“ “ weathered material covering the weathered material covering the earth’s surface that has been affected earth’s surface that has been affected by specific soil-forming processes”by specific soil-forming processes”

--transformations --transformations

--additions, losses--additions, losses

--translocation--translocation

Concepts and Definitions of SoilConcepts and Definitions of Soil► The upper limit of soil is the boundary between The upper limit of soil is the boundary between

soil and air, shallow water, live plants, or plant soil and air, shallow water, live plants, or plant materials that have not begun to decompose. materials that have not begun to decompose.

► The horizontal boundaries of soil are areas The horizontal boundaries of soil are areas where the soil grades to water too deep to where the soil grades to water too deep to support rooted plants, barren areas, rock, or support rooted plants, barren areas, rock, or ice. ice.

► The lower boundary of soil is most difficult to The lower boundary of soil is most difficult to define. define. Soil consists of the horizons have been altered by the Soil consists of the horizons have been altered by the

interactions of climate, relief, and living organisms interactions of climate, relief, and living organisms over time. over time.

Hard rock or earthy materials devoid of biological Hard rock or earthy materials devoid of biological activity are not soil. activity are not soil.

Lower limit of biologic activity is gradual and difficult Lower limit of biologic activity is gradual and difficult to detect.to detect.

For practical and classification purposes, the lower For practical and classification purposes, the lower boundary of soil is arbitrarily set at 200 cm. boundary of soil is arbitrarily set at 200 cm.

Concepts of Soil GenesisConcepts of Soil Genesis► Pedogenic processes active today have been operating Pedogenic processes active today have been operating

over time and have varying degrees of expression over over time and have varying degrees of expression over space. space.

► Many soil-forming processes proceed simultaneously, Many soil-forming processes proceed simultaneously, and the properties of the resulting soil are the result of and the properties of the resulting soil are the result of the balance among the processes. the balance among the processes.

► Distinctive processes produce distinctive soils. Distinctive processes produce distinctive soils. ► Five environmental factors, climate, organisms, relief or Five environmental factors, climate, organisms, relief or

topography, parent material, and time, mediate the topography, parent material, and time, mediate the pedogenic processes. pedogenic processes.

► Current soils carry the imprint of a combination of Current soils carry the imprint of a combination of pedogenic processes that have been active over the pedogenic processes that have been active over the period of soil development.period of soil development.

► A particular site may have had many different soils as A particular site may have had many different soils as one or more of the factors influencing soil formation one or more of the factors influencing soil formation changed over time (changed over time (paleosoilspaleosoils).).

► There are few (very) old soils.There are few (very) old soils.  

A Few DefinitionsA Few Definitions►Regolith: Regolith: ►Pedon: Pedon:   ►Soil profile: Soil profile:   ►Horizon: Horizon: ►Solum: Solum:

Soil PropertiesSoil Properties

Describing soil properties in the field:Describing soil properties in the field:

ColorColor

TextureTexture

StructureStructure

ConsistenceConsistenceand other stuff….and other stuff….

Soil ColorSoil Color

Soil ColorSoil Color

► Obvious property and commonly described Obvious property and commonly described "black soils" "black soils" "red soils" "red soils" "brown soils"brown soils””

► It can be used to infer It can be used to infer minerals present in the soil minerals present in the soil stage of development, and stage of development, and seasonal saturation. seasonal saturation.

► Color also may affect a soil's classification Color also may affect a soil's classification

Soil Coloring AgentsSoil Coloring Agents

► Uncoated mineral grains Uncoated mineral grains Any color Any color Most commonly white to grayMost commonly white to gray

► Coatings on grains Coatings on grains Color depends on compositionColor depends on composition

► Organic matter - brown to black Organic matter - brown to black

Subsoil horizon color is color of Fe and Mn Subsoil horizon color is color of Fe and Mn oxides and oxyhydroxides coating grains.oxides and oxyhydroxides coating grains.

► Hematite (FeHematite (Fe22OO33) - red) - red

► Geothite (Geothite (-FeOOH) -FeOOH) –– yellowish brown yellowish brown► Lepidocrocite (Lepidocrocite (-FeOOH) - orange to yellowish -FeOOH) - orange to yellowish

orangeorange► Mn oxides Mn oxides –– black black

Soil Color DeterminationSoil Color Determination

► The Munsell Color System The Munsell Color System ► The Munsell system has three componentsThe Munsell system has three components

Hue - (page) measure of chromatic composition of Hue - (page) measure of chromatic composition of light reaching the eye. light reaching the eye.

Value - (vertical scale) degree of lightness or Value - (vertical scale) degree of lightness or darkness of a color. darkness of a color.

Chroma - (horizontal scale) relative purity or strength Chroma - (horizontal scale) relative purity or strength of the spectral color. of the spectral color.

► The Munsell notation is written symbolically The Munsell notation is written symbolically as H V/Cas H V/C 2.5YR 6/8. 2.5YR 6/8. The notation for a neutral color is written: N V/; N 5/The notation for a neutral color is written: N V/; N 5/

Munsell Color SpaceMunsell Color Space

Mottles & Redoximorphic FeaturesMottles & Redoximorphic Features► Horizons with multiple colorsHorizons with multiple colors

The dominant color is the The dominant color is the matrixmatrix color color Minor colors are either Minor colors are either mottles mottles or or redoximorphic redoximorphic

featuresfeatures► Mottles - areas of different color due to processes other Mottles - areas of different color due to processes other

than reduction and oxidation of Fe and Mnthan reduction and oxidation of Fe and Mn Does not include coatings or rock fragmentsDoes not include coatings or rock fragments

► Redoximorphic Features - features that have resulted Redoximorphic Features - features that have resulted from reduction, oxidation, and movement of Fe and Mn from reduction, oxidation, and movement of Fe and Mn associated with seasonal saturation.associated with seasonal saturation.

► Both described by abundance, size, contrast, and color Both described by abundance, size, contrast, and color ► Other characteristics can be described if they are Other characteristics can be described if they are

important or diagnostic. important or diagnostic. shape shape boundary boundary location location compositioncomposition

Redoximorphic FeaturesRedoximorphic Features

► Features whose color is the result is Features whose color is the result is reduction, oxidation, and movement of Fe reduction, oxidation, and movement of Fe and Mn because of seasonal saturationand Mn because of seasonal saturation

► Redox depletions - areas with lower Redox depletions - areas with lower chroma than the matrix caused by chroma than the matrix caused by depletion (loss) of Fe and Mn depletion (loss) of Fe and Mn

► Redox concentrations - areas with higher Redox concentrations - areas with higher chroma and/or redder hue than the matrix chroma and/or redder hue than the matrix caused by concentration of Fe and Mn caused by concentration of Fe and Mn

► Mobility of Fe and Mn in soils is related to Mobility of Fe and Mn in soils is related to redox processes caused by saturation with redox processes caused by saturation with water. water.

Redox Feature FormationRedox Feature Formation

►Fe and Mn oxides and oxyhydroxides Fe and Mn oxides and oxyhydroxides (Fe(Fe22OO33, FeOOH; MnO, FeOOH; MnO22, MnOOH; Fe, MnOOH; Fe3+3+ and Mnand Mn4+4+) are very sparingly soluble in ) are very sparingly soluble in water and immobile in soils. water and immobile in soils.

►Reduction of Fe and Mn (FeReduction of Fe and Mn (Fe2+2+ and and MnMn2+2+) changes mineral form and ) changes mineral form and results in compounds that are soluble results in compounds that are soluble in water.in water.

►Dissolution of these compounds Dissolution of these compounds releases Fereleases Fe2+2+ and Mn and Mn2+ 2+ into solution into solution and they can move by mass flow and and they can move by mass flow and diffusion. diffusion.

ReductionReduction

► OO22 is used as the electron acceptor for is used as the electron acceptor for

microbial respirationmicrobial respiration► Diffusion of oxygen into water is slowDiffusion of oxygen into water is slow► Over time, OOver time, O22 in saturated soil will be in saturated soil will be

used up by aerobic microbesused up by aerobic microbes► Facultative anaerobic bacteria Facultative anaerobic bacteria

(thiobacillus species) have ability to use (thiobacillus species) have ability to use other elements as electron acceptors in other elements as electron acceptors in respirationrespiration

► Addition of electrons "reduces" the Addition of electrons "reduces" the element, i.e. Feelement, i.e. Fe+3+3 + e + e-- Fe Fe+2+2

Order of ReductionOrder of Reduction

►Depends on energy of the reactionsDepends on energy of the reactionsOO22 O O-2-2

NONO33-1-1 N N22O or NO or N22 (denitrification) (denitrification)

MnMn+4+4 Mn Mn+2+2

FeFe+3+3 Fe Fe+2+2

SOSO44-2-2 S S-2-2 (H (H22S) (marsh or "rotten egg" S) (marsh or "rotten egg"

gas)gas)

HCOHCO33-1-1, CO, CO22 CH CH44 (methanogenesis) (methanogenesis)

►Poised reactionsPoised reactions

Redox Feature FormationRedox Feature Formation► Reduced Fe and Mn are soluble in waterReduced Fe and Mn are soluble in water

Can move by mass flow and diffusionCan move by mass flow and diffusion► Reduced Fe and Mn oxidize immediately Reduced Fe and Mn oxidize immediately

upon exposure to air and form insoluble upon exposure to air and form insoluble compoundscompounds No longer mobile. No longer mobile.

► Movement of Fe and Mn under reducing Movement of Fe and Mn under reducing conditions form conditions form redox depletionsredox depletions (Fe (Fe and Mn loss) and and Mn loss) and concentrationsconcentrations (gain (gain of Fe and Mn where Oof Fe and Mn where O22 is present) form is present) form by movement of Feby movement of Fe Within a horizonWithin a horizon Between horizons Between horizons Across the landscapeAcross the landscape

Redox Feature FormationRedox Feature Formation

► Depletion of Fe removes the Fe coatings Depletion of Fe removes the Fe coatings that give the horizon the yellowish, that give the horizon the yellowish, brownish, or red color. brownish, or red color. Color of the zone is that of uncoated mineral Color of the zone is that of uncoated mineral

grains grains Reduced Fe is also grayReduced Fe is also gray

► Soil horizons may have reduced micro-Soil horizons may have reduced micro-sites and oxidized microsites at the same sites and oxidized microsites at the same timetime

Fe2+

105 to 150 cm; light gray (10YR 7/2) clay loam; many medium and coarse, distinct light yellowish brown (10YR 6/4) redox concentrations; weak medium subangular blocky structure; friable, sticky, slightly plastic; common fine flakes of mica; common faint clay films on faces of peds; very strongly acid; clear smooth boundary.

Describing Redox FeaturesDescribing Redox Features

Abundance:Abundance:► few - <2% of volume of layerfew - <2% of volume of layer► common - 2-20% of volume of common - 2-20% of volume of

layerlayer► many - >20% of volume of layermany - >20% of volume of layer

Size:Size:► fine - smaller than 2 mmfine - smaller than 2 mm► medium - 2 to 5 mmmedium - 2 to 5 mm► coarse - 5 to 20 mmcoarse - 5 to 20 mm► very coarse - >20 mmvery coarse - >20 mm

Contrast:Contrast:

faint, distinct, prominentfaint, distinct, prominent

Conditions for Redox Feature FormationConditions for Redox Feature Formation

► Saturation with waterSaturation with water► Presence of facultative anaerobic bacteria Presence of facultative anaerobic bacteria ► Organic matter as a food source Organic matter as a food source

Faster reduction in surface horizonsFaster reduction in surface horizons Depletions common around dead rootsDepletions common around dead roots

► FeFe Always present except a few sandy soilsAlways present except a few sandy soils

► TimeTime 2 to 3 three weeks of saturation for Fe reduction2 to 3 three weeks of saturation for Fe reduction

► Shorter periods will not form redox featuresShorter periods will not form redox features Water movement and diffusion are slowWater movement and diffusion are slow

► 1010’’s to 100s to 100’’s of years to form visible redox featuress of years to form visible redox features

TextureTexture► Refers to size and relative abundance of mineral Refers to size and relative abundance of mineral

particles comprising a soil horizon or soil sample.particles comprising a soil horizon or soil sample.► Soil separates - individual size groups of mineral Soil separates - individual size groups of mineral

particles.particles.SeparateSeparate Size (mm)Size (mm)

StonesStones >250>250

CobblesCobbles 76-25076-250

GravelGravel 2-762-76

SandSand 0.05-20.05-2

Very coarseVery coarse 1-21-2

CoarseCoarse 0.5-10.5-1

MediumMedium 0.25-0.50.25-0.5

FineFine 0.1-0.250.1-0.25

Very fineVery fine 0.05-0.10.05-0.1

SiltSilt 0.002-0.050.002-0.05

ClayClay <0.002<0.002

Textural TriangleTextural Triangle

► A system that groups ranges of A system that groups ranges of sand, silt, and clay percentages sand, silt, and clay percentages into classesinto classes

► Sand, loamy sand, and sandy Sand, loamy sand, and sandy loam textures are modified by loam textures are modified by the dominant size class of the the dominant size class of the sand (very fine, fine, or sand (very fine, fine, or coarse).coarse).

► In FIELD: “feel” method for In FIELD: “feel” method for estimating particle size estimating particle size (textural classes) based on :(textural classes) based on : ““gritty” vs. “smooth”gritty” vs. “smooth” Cohesiveness (ribbon length)Cohesiveness (ribbon length)

1 02 03 04 05 06 07 08 09 01 0 0

1 0

2 0

1 0 0

3 0

4 0

5 0

6 0

7 0

8 0

9 0

1 0 0

9 0

8 0

7 0

6 0

5 0

4 0

3 0

2 0

1 0

% Sand

Textural Triangle

C lay (c )

SandyC lay (sc)

C lay loam (c l)

Silty c lay (s ic )

Silty c layloam (s ic l)

Sandy c layloam (scl)

Loam (l)

Sandy loam (s l) Silt loam (s il)

Silt (s i)Sand (s)

Textural Modifiers for Rock FragmentsTextural Modifiers for Rock Fragments

Volume % FragmentsVolume % Fragments Modifier UsedModifier Used

<15<15 nonenone

15-3515-35 gravelly, stony, bouldery, flaggy, i.e. gravelly loam gravelly, stony, bouldery, flaggy, i.e. gravelly loam (grl)(grl)

35-6035-60 add very, i.e. very gravelly loam (vgrl)add very, i.e. very gravelly loam (vgrl)

>60>60 add extremely, i.e. extremely gravelly loam (exgrl)add extremely, i.e. extremely gravelly loam (exgrl)ShapeShape Size (mm)Size (mm) TermTerm

rounded, subrounded, angular, or rounded, subrounded, angular, or irregularirregular

2-762-76 gravellygravelly

76-25076-250 cobblycobbly

250-600250-600 stonystony

>600>600 boulderybouldery

flat (length of long axis)flat (length of long axis) 5-1505-150 channerychannery

150-380150-380 flaggyflaggy

380-600380-600 stonystony

>600>600 boulderybouldery

Importance of TextureImportance of Texture

► Many soil interpretations are based on Many soil interpretations are based on texture or combination or texture and texture or combination or texture and other propertiesother properties Water holding capacity (agricultural use) Water holding capacity (agricultural use) Permeability, bearing capacity (urban uses)Permeability, bearing capacity (urban uses)

► Many pedogenic pathways and Many pedogenic pathways and processes are inferred from texture and processes are inferred from texture and the distribution of texture with depth.the distribution of texture with depth. Weathering rates (clay formation in situ)Weathering rates (clay formation in situ) Translocation (clay movement with depth)Translocation (clay movement with depth)

Soil StructureSoil Structure

► The aggregation of primary soil particles into The aggregation of primary soil particles into compound particles called peds.compound particles called peds.

► Structure is described in terms of grade, size, Structure is described in terms of grade, size, and shape.and shape.

► Grade - distinctness or degree of expression of peds. Grade - distinctness or degree of expression of peds. ► weakweak► moderate moderate ► strongstrong

► Size:Size: fine <2 mmfine <2 mm

medium 2-5 mmmedium 2-5 mm

coarse 5-20 mmcoarse 5-20 mm

very coarse 20-76 mmvery coarse 20-76 mm

extremely coarse >76 mmextremely coarse >76 mm

ShapeShape

Structure Shape Structure Shape

Prismatic Prismatic

Columnar Columnar

Subangular BlockySubangular Blocky

GranularGranular

Structure FormationStructure Formation

► Biologic processes in surface horizonsBiologic processes in surface horizons Organic compounds from root and microbial Organic compounds from root and microbial

exudates bind soil particles exudates bind soil particles Granular structure is commonGranular structure is common Fecal pellets from earthworms, insects, and other Fecal pellets from earthworms, insects, and other

critters.critters.

► Shrink swell in subsoil horizonsShrink swell in subsoil horizons Once planes of weakness are formed by shrinkage, Once planes of weakness are formed by shrinkage,

the soil will continue to fail along these planes the soil will continue to fail along these planes Fe and Al oxides and clay binds particles and Fe and Al oxides and clay binds particles and

coatings on ped surfaces enhances strength and coatings on ped surfaces enhances strength and expression of structureexpression of structure

Shrink/swell is driven by water content: wetting by Shrink/swell is driven by water content: wetting by rainfall, drying by evapotranspiration (rainfall, drying by evapotranspiration (water balancewater balance))

Importance of StructureImportance of Structure

► May have large impact on rates of water movement May have large impact on rates of water movement through the soil, ease of tillage, aeration, and other through the soil, ease of tillage, aeration, and other properties. properties. In soils with low shrink-swell, structure creates an In soils with low shrink-swell, structure creates an

extensive network of macropores that can move water extensive network of macropores that can move water rapidly under saturated conditions rapidly under saturated conditions

Too much structure may be detrimental. Too much structure may be detrimental. "Response of soil to management may depend as much on "Response of soil to management may depend as much on

its structure as on its fertility."its structure as on its fertility."

 

HorizoHorizonn

Depth Depth (cm)(cm)

StructureStructure TextureTexture KKss (cm/h) (cm/h)

BtBt 6060 moderate subangular moderate subangular blockyblocky

clayclay 1717

BCBC 9090 weak subangular weak subangular blockyblocky

sandy clay sandy clay loamloam

66

CC 120120 massivemassive sandy loamsandy loam 44

Thin-section Images of Structure and PoresThin-section Images of Structure and Pores

ConsistenceConsistence► Compressive strength of ped (structural unit) Compressive strength of ped (structural unit) ► Resistance to deformation under pressureResistance to deformation under pressure► Depends on moisture state Depends on moisture state

Dry soil is more difficult to deform than moist soilDry soil is more difficult to deform than moist soil Different terms for different moisture states (moist and dry).Different terms for different moisture states (moist and dry).

► Moist Moist loose, very friable, friable, firm, very firm, extremely firmloose, very friable, friable, firm, very firm, extremely firm

► Dry Dry loose, soft, slightly hard, hard, very hard, extremely hardloose, soft, slightly hard, hard, very hard, extremely hard

► Specimen to be tested should be 25-30 mm (1 in.) on Specimen to be tested should be 25-30 mm (1 in.) on edge.edge.

► Wet or puddled soilWet or puddled soil stickiness - nonsticky, slightly sticky, sticky, very stickystickiness - nonsticky, slightly sticky, sticky, very sticky plasticity - nonplastic, slightly plastic, plastic, very plasticplasticity - nonplastic, slightly plastic, plastic, very plastic

► Other terms are also used to describe brittleness, Other terms are also used to describe brittleness, cementation, strength, smeariness, and fluidity.cementation, strength, smeariness, and fluidity.

ConcentrationsConcentrations► Bodies that have a different color, texture, and/or Bodies that have a different color, texture, and/or

composition than the matrix composition than the matrix ► Formed by concentration (accumulation) of mobile Formed by concentration (accumulation) of mobile

components (Fe, CaCOcomponents (Fe, CaCO33, gypsum, etc)., gypsum, etc).

► In humid climates, related to seasonal saturation and In humid climates, related to seasonal saturation and associated mobility of Fe and Mn oxides associated mobility of Fe and Mn oxides

► In drier climates, result from translocation of soluble or In drier climates, result from translocation of soluble or sparingly soluble minerals such as calcite or gypsum.sparingly soluble minerals such as calcite or gypsum.

► May be thin and sheet like, equidimensional, or irregular May be thin and sheet like, equidimensional, or irregular ► May contrast with the surrounding matrix or may be May contrast with the surrounding matrix or may be

similar similar ► Rock fragments are not considered concentrationsRock fragments are not considered concentrations► Any number of properties of concentrations can be Any number of properties of concentrations can be

described described Most commonly described characteristics include amount, Most commonly described characteristics include amount,

size, shape, consistence, color(s), kind and locationsize, shape, consistence, color(s), kind and location

Kinds of ConcentrationsKinds of Concentrations► Masses - soft accumulations;Masses - soft accumulations;

Do not have clearly defined boundaries Do not have clearly defined boundaries Composition may be similar to or different from the Composition may be similar to or different from the

surrounding soil surrounding soil Cannot be separated from the matrix and removed Cannot be separated from the matrix and removed

as a discrete unitas a discrete unit► Nodules and concretions Nodules and concretions

Have clearly defined boundaries and can be removed Have clearly defined boundaries and can be removed from the soil intact from the soil intact

► Crystals Crystals ► PlinthitePlinthite

Fe concentration that can separated from Fe concentration that can separated from surrounding soil, but can be broken between the surrounding soil, but can be broken between the fingers fingers

► IronstoneIronstone Hardened plinthite Hardened plinthite

Kinds of ConcentrationsKinds of Concentrations

Ped Surface FeaturesPed Surface Features► Coatings of unlike material Coatings of unlike material ► Material concentrated on ped surfaces by Material concentrated on ped surfaces by

removal of other material removal of other material ► Stress features Stress features ► Describe Describe

amount, distinctness, color, texture, kind, location, amount, distinctness, color, texture, kind, location, and any other property that can be observed and is and any other property that can be observed and is important.important.

► Kinds of ped surface features:Kinds of ped surface features: Clay films Clay films Clay bridgesClay bridges Sand or silt coats (skeletans) Sand or silt coats (skeletans) Other coatings Other coatings Stress surfacesStress surfaces Slickensides Slickensides

Clay Films and BridgesClay Films and Bridges

SlickensidesSlickensides

PoresPores► 3 kinds of pores3 kinds of pores

Matrix pores Matrix pores ► Formed by packing of primary particles or may be the result of Formed by packing of primary particles or may be the result of

entrapped airentrapped air► May or may not be continuousMay or may not be continuous

Non-matrix pores (biopores)Non-matrix pores (biopores)► formed by actions of roots and burrowing animals formed by actions of roots and burrowing animals ► Commonly large and continuousCommonly large and continuous

Inter-structural poresInter-structural pores► Pores between peds in structured soilsPores between peds in structured soils► Relatively large and continuousRelatively large and continuous

► Descriptions of pores can include quantity, size, Descriptions of pores can include quantity, size, location, and vertical continuity.location, and vertical continuity.

► Most descriptions of pores address only coarser matrix Most descriptions of pores address only coarser matrix and the non-matrix poresand the non-matrix pores Inter-structural pores are not easily observableInter-structural pores are not easily observable

Roots and AnimalsRoots and Animals► RootsRoots

Describe quantity, size, Describe quantity, size, and locationand location

► AnimalsAnimals Features related to Features related to

animal activity (burrows, animal activity (burrows, mounds, castings, etc.) mounds, castings, etc.)

Animal burrows Animal burrows (biopores) are described (biopores) are described with the same terms as with the same terms as porespores

Other animal features Other animal features (castings, mounds, etc.) (castings, mounds, etc.) have no special terms for have no special terms for description description

Krotovina Krotovina ► Coarse infilled animal Coarse infilled animal

burrowburrow

KrotovinaKrotovina

Rock FragmentsRock Fragments► Can be described with a range of terms that Can be described with a range of terms that

include:include: Amount (estimate % by volume)Amount (estimate % by volume) Size (give dimension as diameter, long axis, etc.)Size (give dimension as diameter, long axis, etc.) Color (if important)Color (if important) Hardness (hard, soft, weathered, etc.)Hardness (hard, soft, weathered, etc.) Composition (limestone, schist, sandstone, Composition (limestone, schist, sandstone,

pumice, basalt, etc.)pumice, basalt, etc.) Orientation from horizontal (if can be Orientation from horizontal (if can be

determined)determined) Angularity (angular, subangular, subrounded, Angularity (angular, subangular, subrounded,

rounded)rounded) Other features (as beds, weathered dyke, etc.)Other features (as beds, weathered dyke, etc.)

► Rock fragments may also be referred to as Rock fragments may also be referred to as coarse fragments coarse fragments or simply as or simply as fragmentsfragments..

Horizon BoundaryHorizon Boundary► Refers to lower boundary of horizon being described Refers to lower boundary of horizon being described ► Distinctness - thickness of transition from the horizon Distinctness - thickness of transition from the horizon

being describedto the subjacent horizonbeing describedto the subjacent horizon► Topography - deviation from a planeTopography - deviation from a plane

DistinctnesDistinctnesss

Thickness of Transsition Thickness of Transsition (cm)(cm)

AbruptAbrupt <2<2

ClearClear 2-62-6

GradualGradual 6-156-15

DiffuseDiffuse >15>15

Horizon BoundaryHorizon Boundary

105 to 150 cm; light gray (10YR 7/2) silt loam; many medium and coarse, distinct light yellowish brown (10YR 6/4) redox concentrations; weak medium subangular blocky structure; friable, sticky, slightly plastic; common fine flakes of mica; common faint clay films on faces of peds; very strongly acid; clear smooth boundary.

Horizon DesignationsHorizon Designations

► Master HorizonsMaster Horizons O - layers dominated by organic material in various O - layers dominated by organic material in various

stages of decomposition from fully decayed "humus" stages of decomposition from fully decayed "humus" to fresh litter.to fresh litter.

A - mineral horizons formed at the soil surface or A - mineral horizons formed at the soil surface or below an O horizon; characterized by accumulation below an O horizon; characterized by accumulation of organic matter (dark color) or having properties of organic matter (dark color) or having properties resulting from cultivation, pasturing, etc.resulting from cultivation, pasturing, etc.

E - mineral horizons in which the main feature is loss E - mineral horizons in which the main feature is loss of clay, Fe, and Al leaving a concentration of quartz of clay, Fe, and Al leaving a concentration of quartz and other resistant minerals.and other resistant minerals.

Master Horizons, con’tMaster Horizons, con’t► B -B - mineral horizons formed below an A, E, mineral horizons formed below an A, E,

or O horizon that are dominated by or O horizon that are dominated by obliteration of the rock structure and by obliteration of the rock structure and by pedogenic alteration, evidenced as:pedogenic alteration, evidenced as: illuvial accumulation of clay, Fe, humus, carbonates, illuvial accumulation of clay, Fe, humus, carbonates,

gypsum, or silica;gypsum, or silica; evidence of carbonate removal; evidence of carbonate removal; residual concentration of sesquioxides;residual concentration of sesquioxides; coatings of sesquioxides that make the horizon lower coatings of sesquioxides that make the horizon lower

in value, higher in chroma, or redder in hue than the in value, higher in chroma, or redder in hue than the overlying and underlying horizons;overlying and underlying horizons;

alteration that forms clay or liberates oxides and alteration that forms clay or liberates oxides and forms soil structure; forms soil structure;

brittleness; orbrittleness; or strong gleyingstrong gleying

► C -C - horizons, excluding hard bedrock, that horizons, excluding hard bedrock, that are little affected by pedogenic processes.are little affected by pedogenic processes.

► R -R - hard bedrock.hard bedrock.

Transition HorizonsTransition Horizons

► Two typesTwo types Homogenous horizon dominated by properties Homogenous horizon dominated by properties

of one master horizon but having subordinate of one master horizon but having subordinate properties of another. properties of another.

► Use two capital letter symbols, i.e. AE, EB, BE, etc. to Use two capital letter symbols, i.e. AE, EB, BE, etc. to ► The first letter is the master horizon with dominate The first letter is the master horizon with dominate

properties. properties.

horizon that has distinct zones with horizon that has distinct zones with recognizable properties of two master horizonsrecognizable properties of two master horizons

► a mixed horizon but the components can be a mixed horizon but the components can be recognized as distinct zones rather than being recognized as distinct zones rather than being homogenized. homogenized.

► designated by two master horizon symbols separated designated by two master horizon symbols separated by a "/by a "/““; e.g., ; e.g., ““B/CB/C””

► The first letter symbol is the dominate component. The first letter symbol is the dominate component.

Subordinate Distinctions within Master HorizonsSubordinate Distinctions within Master Horizons

aa - highly decomposed organic material; used with O - highly decomposed organic material; used with O

b - buried genetic horizonb - buried genetic horizon

c - concretions (or nodules) of Fe, Al, Mn, or Ti; not used for c - concretions (or nodules) of Fe, Al, Mn, or Ti; not used for carbonates or soluble saltscarbonates or soluble salts

d - physical root restrictiond - physical root restriction

ee - organic material of intermediate decomposition; used - organic material of intermediate decomposition; used with Owith O

f - permanently frozen soilf - permanently frozen soil

ff - dry permafrostff - dry permafrost

gg - strong gleying; dominant color has chroma of 2 or less - strong gleying; dominant color has chroma of 2 or less

hh - illuvial accumulation of organic matter; used with B - illuvial accumulation of organic matter; used with B

ii - slightly decomposed organic material; used with O - slightly decomposed organic material; used with O

j - accumulation of jarositej - accumulation of jarosite

jj - evidence of cryoturbationjj - evidence of cryoturbation

k - accumulation of carbonatesk - accumulation of carbonates

Subordinate Distinctions within Master Horizons, con’tSubordinate Distinctions within Master Horizons, con’t

m - cementation or induration; used with symbol for m - cementation or induration; used with symbol for cementing material, i.e. Bkm, Bsm, etc.cementing material, i.e. Bkm, Bsm, etc.

n - accumulation of sodiumn - accumulation of sodiumo - residual accumulation of sesquioxides; B onlyo - residual accumulation of sesquioxides; B onlypp - plowing; used only with surface horizon (A) - plowing; used only with surface horizon (A)q - accumulation of silicaq - accumulation of silicarr - weathered or soft bedrock; only used with C, i.e. Cr - weathered or soft bedrock; only used with C, i.e. Crss - illuvial accumulation of sesquioxides and organic matter; - illuvial accumulation of sesquioxides and organic matter;

BBss - slickensidesss - slickensidestt - illuvial accumulation of silicate clay; clay films or bridges; - illuvial accumulation of silicate clay; clay films or bridges;

BBvv –– plinthite; B plinthite; Bww - development of color or structure; used with B horizon - development of color or structure; used with B horizonx - brittle consistence; Bx - brittle consistence; By - accumulation of gypsumy - accumulation of gypsumz - accumulation of salts more soluble than gypsumz - accumulation of salts more soluble than gypsum

OO `̀ Use ONLY ONE of “a”, “e”, OR “i”; may use “b” (use LAST)Use ONLY ONE of “a”, “e”, OR “i”; may use “b” (use LAST)

  

AA “p” is common, used ONLY with A; place first.“p” is common, used ONLY with A; place first.

May use “b”, “c”, “g” (rarely—if all lower horizons are gleyed) May use “b”, “c”, “g” (rarely—if all lower horizons are gleyed)

  

EE May use “b”, “c”, “g” (rarely—if chroma≤2, redox features present)May use “b”, “c”, “g” (rarely—if chroma≤2, redox features present)

  

BB Following take precedence (in order), used FIRST, and only Following take precedence (in order), used FIRST, and only SINGALLY:SINGALLY:

““t”t”

““h” or “hs”h” or “hs”

““w” or “g” (used by itself)w” or “g” (used by itself)

Following may be used ALONE or in combination with above:Following may be used ALONE or in combination with above:

““k”, “d”,”f”,”j”,”jj”,”k”,”n”,”o”,”q”,”ss”,”v”,”x”,”y”,”z” k”, “d”,”f”,”j”,”jj”,”k”,”n”,”o”,”q”,”ss”,”v”,”x”,”y”,”z”

(largely with “t”)(largely with “t”)”g” may be added to “t””g” may be added to “t”

““m” is used following “k”,”q”, or “s” (cementing agents)m” is used following “k”,”q”, or “s” (cementing agents)

““c”, “f”, “g”, “m”, and “x” are written last.c”, “f”, “g”, “m”, and “x” are written last.

   ““b” is always the very last designation (if needed).b” is always the very last designation (if needed).

CC Only use “g” and/or ”r”Only use “g” and/or ”r”

   ““b” is never used with Cb” is never used with C

RR No suffixesNo suffixes

Conventions for using letter suffixesConventions for using letter suffixes

Horizon Designations – Other ConsiderationsHorizon Designations – Other Considerations

Vertical subdivisionMore than one horizon may have the same designation. For these cases, Arabic numerals following the letters are used to differentiate the horizons, i.e. Bt1, Bt2, Bt3

DiscontinuitiesArabic numerals are used as prefixes to indicate lithologic discontinuities (changes in parent materials): Btg, 2BC, 2C

Use of Prime (')Use prime (') for the lower of two horizons with identical designations that are separated by at least one horizon.(A, E, Bhs, E’, Bhs’, C)

CRSS 4540/6540CRSS 4540/6540PedologyPedology

William MillerWilliam MillerOffice: 3107 Plant SciencesOffice: 3107 Plant Sciences

Phone: 706-542-0896Phone: 706-542-0896 email: wmiller@uga.eduemail: wmiller@uga.edu

Larry MorrisLarry MorrisOffice: 4-303 ForestryOffice: 4-303 Forestry

Phone: 706-542-2532Phone: 706-542-2532 email: lmorris@uga.eduemail: lmorris@uga.edu

Course ObjectivesCourse Objectives► To be able to describe, using proper To be able to describe, using proper

terminology, the morphological characteristics terminology, the morphological characteristics of soils as they are found in their natural of soils as they are found in their natural setting. setting.

► To understand processes and factors To understand processes and factors important to the formation and distribution of important to the formation and distribution of soils. soils.

► To understand the rationale and structure of To understand the rationale and structure of Soil Taxonomy and be able to classify soils Soil Taxonomy and be able to classify soils using the system. using the system.

► To be able to interpret soil behavior and To be able to interpret soil behavior and understand proper soil use and management understand proper soil use and management based on a soils morphology, landscape based on a soils morphology, landscape setting, and classification. setting, and classification.

GradingGrading

Two examsTwo exams 40%40%

HomeworkHomework 10%10%

LaboratoryLaboratory 20%20%

Final examFinal exam 30%30%

Homework Homework –– soil descriptions soil descriptions

Laboratory Laboratory –– field observation and field observation and descriptions; mapping exercisedescriptions; mapping exercise

1-day trip to Blue Ridge Mountains 1-day trip to Blue Ridge Mountains

2-day trip to the Georgia Coastal 2-day trip to the Georgia Coastal PlainPlain