know your soil powerpoint

8/6/2019 Know Your Soil Powerpoint

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Soil TextureSoil Texture

Presented by:Presented by:

Mr. Brian Oram, PG, PASEOMr. Brian Oram, PG, PASEO

Wilkes UniversityWilkes University

GeoEnvironmental Sciences andGeoEnvironmental Sciences and

Environmental Engineering DepartmentEnvironmental Engineering Department

WilkesWilkes -- Barre, PA 18766Barre, PA 18766

570570--408408--46194619

http://www.waterhttp://www.water--research.netresearch.net


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Quick ReviewQuick Review


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Major Components of SoilMajor Components of Soil

Pore Space (50%)Pore Space (50%)

This may contain air and/orThis may contain air and/or

waterwater

Soil Space (50%)

Organic Matter

Mineral Matter


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Master Soil HorizonsMaster Soil Horizons O HorizonO Horizon-- leaf litter / humusleaf litter / humus

A HorizonA Horizon-- organic accumulationorganic accumulationin mineral soilin mineral soil

E HorizonE Horizon-- leached horizonleached horizon

(elluviation)(elluviation)

B HorizonB Horizon-- zone of illuviationzone of illuviation

C HorizonC Horizon unconsolidated parentunconsolidated parent

materialmaterial R HorizonR Horizon Lithic materialLithic material

(Rock)(Rock)

R

Not All the Master Horizons Will Be Present in All Profiles


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Mineral SoilMineral Soil Is never saturated with water for more than a fewIs never saturated with water for more than a few

days and contains less than 20 % (by weight) organicdays and contains less than 20 % (by weight) organiccarboncarbon

Is saturated with water for longer periods orIs saturated with water for longer periods or

artificially drained and excluding live roots, has anartificially drained and excluding live roots, has anorganicorganic--carbon content of:carbon content of: Less than 18 % if the mineral fraction contains 60% orLess than 18 % if the mineral fraction contains 60% or

more clay;more clay;

Less than 12 %, if the mineral fraction contains no clays; orLess than 12 %, if the mineral fraction contains no clays; or

Less than 12 + (clay percentage multiplied by 0.1) %, if theLess than 12 + (clay percentage multiplied by 0.1) %, if themineral fraction contains less than 60%.mineral fraction contains less than 60%.

Soil material containing more than the above organic carbon is an organic soil.


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Describing Soil MorphologyDescribing Soil Morphology

for Mineral Soilfor Mineral Soil

Soil Texture and Coarse Fragment ContentSoil Texture and Coarse Fragment Content

Soil StructureSoil Structure

Soil ColorSoil Color

ConsistencyConsistency

Redoximorphic FeaturesRedoximorphic Features

BoundariesBoundaries


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Describes the mineral content of the soilDescribes the mineral content of the soil -- Which isWhich istypically less than 50% of the soil volume.typically less than 50% of the soil volume.

Soil texture is based on a weight ratio of the 3 soilSoil texture is based on a weight ratio of the 3 soilseparates (sand, silt, and clay).separates (sand, silt, and clay).

Material > 2mm are coarse fragments or rockMaterial > 2mm are coarse fragments or rockfragments and used as a modifier to the soil texturefragments and used as a modifier to the soil textureterm. Modifier used only when the fragmentsterm. Modifier used only when the fragmentsrepresent more than 15 % of the soil volume.represent more than 15 % of the soil volume.

Material < 2mm represent the three (3) soil separates.Material < 2mm represent the three (3) soil separates. SandSand -- 2.02.0 -- 0.05 mm0.05 mm -- GRITTY Feel !GRITTY Feel !

SiltSilt -- 0.050.05 -- 0.002 mm0.002 mm TalcTalc Floury Feel !Floury Feel !

ClayClay -- < 0.002 mm< 0.002 mm Tends to be Sticky when Wet !Tends to be Sticky when Wet !


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Particle Size Classification SystemsParticle Size Classification Systems

USDA SystemUSDA System Soil description for agricultural, landSoil description for agricultural, land--basedbasedwastewater disposal, and most environmental applications.wastewater disposal, and most environmental applications.

(i.e., loam)(i.e., loam)

AASHTO:AASHTO: American Association of State Highways andAmerican Association of State Highways andTransportation ProjectsTransportation Projects potential use as road base (i.e., Apotential use as road base (i.e., A--1)1)

Unified Soil Classification System (ASTMD2487Unified Soil Classification System (ASTMD2487--92)92)EngineeringEngineering Applications (i.e., SM)Applications (i.e., SM)

WentworthWentworth (phi #)(phi #)-- Geological and Geotechnical StudiesGeological and Geotechnical StudiesUsing screen or sieve size using the phi number. (phi #, sieveUsing screen or sieve size using the phi number. (phi #, sieveno., or mm)no., or mm)

Each system has unique (jargon or terminology)Each system has unique (jargon or terminology)


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USDA ParticleUSDA Particle--Size DistributionSize Distribution

This is the Particle System we will use in the course.This is the Particle System we will use in the course.

System is divided into: fineSystem is divided into: fine--earth fraction and rock fragments.earth fraction and rock fragments.

FineFine--earth fraction: Finer than 2 mm: This is the information used to describeearth fraction: Finer than 2 mm: This is the information used to describethe soil and is the Soil Textural Class, such as sandy loam. Classificationthe soil and is the Soil Textural Class, such as sandy loam. Classificationbased on weight of 3 soil separates.based on weight of 3 soil separates.

Rock fragments: 2 mm in diameter or larger. These are commonly describedRock fragments: 2 mm in diameter or larger. These are commonly describedas part of the coarse fragment content.as part of the coarse fragment content.

The rock fragment modifier is based on a volumetric fraction of the soil and isThe rock fragment modifier is based on a volumetric fraction of the soil and isused as a soil modifier. Thereforeused as a soil modifier. Therefore Gravels made up 30 % of the volume forGravels made up 30 % of the volume fora sandy loam the full description would bea sandy loam the full description would be gravelly sandy loam.gravelly sandy loam.


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FineFine--earth fractionearth fraction

The Three Soil SeparatesThe Three Soil Separates

SandSand -- 2.02.0 -- 0.05 mm0.05 mm

SiltSilt 5050 2 um2 um

ClayClay -- < 2 um< 2 um


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USDA and NRCSUSDA and NRCS

Textural Classes (12)Textural Classes (12) Sand (S)Sand (S)

Loamy Sand (LS)Loamy Sand (LS)

Sandy Loam (SL)Sandy Loam (SL)

Loam (L)Loam (L) Silt Loam (SIL)Silt Loam (SIL)

Silt (SI)Silt (SI)

Sandy Clay LoamSandy Clay Loam(SCL)(SCL)

Silty Clay LoamSilty Clay Loam

(SICL)(SICL) Clay LoamClay Loam

(CL)(CL)

Sandy ClaySandy Clay

(SCL)(SCL) Silty ClaySilty Clay

(SIC)(SIC)

Clay ( C)Clay ( C)


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Sand + Silt + Clay

= 100%

Texture = LOAM

40 % Sand

40 % Silt

20 % Clay


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The 21 SubclassesThe 21 Subclasses

in Soil Texturein Soil Texture

There are 12 soil texture classes.There are 12 soil texture classes.

When a sand modifier is added there can be 21When a sand modifier is added there can be 21total subclasses, but 22 subclasses if verytotal subclasses, but 22 subclasses if very

coarse sandy loam is included.coarse sandy loam is included.

FractionFraction SizeSize (mm)(mm)

Very coarse sand.....................................2.0 to 1.0Very coarse sand.....................................2.0 to 1.0

Coarse sand.............................................1.0 to 0.5Coarse sand.............................................1.0 to 0.5

Medium sand.........................................0.5 to 0.25Medium sand.........................................0.5 to 0.25

Fine sand..............................................0.25 to 0.10Fine sand..............................................0.25 to 0.10

Very fine sand......................................0.10 to 0.05Very fine sand......................................0.10 to 0.05


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Soil Texture SubclassesSoil Texture Subclasses

SANDS (5)SANDS (5)

Very Coarse SandVery Coarse Sand

(VCOS)(VCOS)

Coarse Sand (COS)Coarse Sand (COS)

Sand (S)Sand (S)

Fine Sand (FS)Fine Sand (FS)

Very Fine Sand (VFS)Very Fine Sand (VFS)

LOAMY SANDS (4)LOAMY SANDS (4)

Loamy Coarse SandLoamy Coarse Sand

(LCOS)(LCOS)

Loamy Sand (LS)Loamy Sand (LS)

Loamy Fine Sand (LFS)Loamy Fine Sand (LFS)

Loamy Very Fine SandLoamy Very Fine Sand(LVFS)(LVFS)


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SANDY LOAMS (4)SANDY LOAMS (4)

Coarse Sandy LoamCoarse Sandy Loam

(COSL)(COSL)

Sandy Loam (SL)Sandy Loam (SL)

Fine Sandy Loam (FSL)Fine Sandy Loam (FSL)

Very Fine Sandy Loam|Very Fine Sandy Loam|(VFSL)(VFSL)

LOAMS (3)LOAMS (3)

Loam (L)Loam (L)

Silt Loam (SIL)Silt Loam (SIL)

Silt (SI)Silt (SI)


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CLAY LOAMS (3)CLAY LOAMS (3)

Sandy Clay LoamSandy Clay Loam

(SCL)(SCL)

Clay Loam (CL)Clay Loam (CL)

Silty Clay Loam (SICL)Silty Clay Loam (SICL)

CLAYS (3)CLAYS (3)

Sandy Clay (SC)Sandy Clay (SC)

Silty Clay (SIC)Silty Clay (SIC)

Clay ( C )Clay ( C )


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Using Rock Fragment ModifiersUsing Rock Fragment Modifiers

Divided intoDivided into Spherical (cubelike)Spherical (cubelike) andand Flat UnitsFlat Units

Less than 15 percent: No adjective or modifier terms are used.Less than 15 percent: No adjective or modifier terms are used.

15 to 35 percent: The dominant kind of rock fragment is used as an adjective15 to 35 percent: The dominant kind of rock fragment is used as an adjectiveie. "ie. "gravellygravelly loam.loam.

35 to 60 percent: An adjective term with the word "very" is used ie. "35 to 60 percent: An adjective term with the word "very" is used ie. "veryverygravelly loam.gravelly loam.

More than 60 percent: An adjective term with the word extremely" is usedMore than 60 percent: An adjective term with the word extremely" is used

i.e., "i.e., "extremelyextremely gravelly loam."gravelly loam."

NOTE:NOTE:

> 90 %, less than 10 % soil separates it may be advisable to use the rock fragment> 90 %, less than 10 % soil separates it may be advisable to use the rock fragmentmodifiermodifier such as gravel.such as gravel.


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Estimating Rock Fabric ContentEstimating Rock Fabric Content


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How Do WeHow Do WeDetermine Texture ?Determine Texture ?


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Determination of TextureDetermination of Texture

Field ProcedureField Procedure

The Feel MethodThe Feel Method

Estimating Sand and Clay ContentEstimating Sand and Clay Content Field Test KitField Test Kit Volume MethodVolume Method

Laboratory ProcedureLaboratory Procedure

HydrometerHydrometer

SieveSieve

PipettePipette


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Field Determination ofField Determination of

TextureTexture-- The Feel MethodThe Feel Method


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Method 1: The Feel MethodMethod 1: The Feel Method

Key Features or Characteristic that We UseKey Features or Characteristic that We Use

Cast Formation and StabilityCast Formation and Stability

FeelFeel Grittiness, Floury, and StickyGrittiness, Floury, and Sticky Ribbon LengthRibbon Length

Evaluate Samples that are Moist, but noteEvaluate Samples that are Moist, but note

characteristics when the material is dry and wet.characteristics when the material is dry and wet.

See Feel ofTextural Classes in Appendix CSee Feel ofTextural Classes in Appendix C

of the Course Documentation.of the Course Documentation.


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Go to this Handoutin Appendix C of the

Course Manual.


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Feel Method ofFeel Method of

Determination of TextureDetermination of Texture

Soil must be moist, not saturated; moistSoil must be moist, not saturated; moist

enough to mold like putty when you try toenough to mold like putty when you try to

form a ball in your hand.form a ball in your hand.

Question 1:Question 1: Does soil form a ball or cast?Does soil form a ball or cast?

NoNo -- the texture isthe texture isSANDSAND

Question 2: Does the soil form a stable cast,

but does not form a ribbon

No the texture is loamy sand


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Soil does not form a cast:

Textural class is SAND

ThankYou Dr. David Lindo (NCSU)


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Determination of Texture (continued)Determination of Texture (continued)

Question 3:Question 3: Does soil form a weak ribbon lessDoes soil form a weak ribbon less

than 2.5 cm?than 2.5 cm?

YesYes -- the possible textures are sandy loam, siltthe possible textures are sandy loam, silt

loam, or loamloam, or loam

Does the soil feel gritty?Does the soil feel gritty? -------------- Sandy LoamSandy Loam

Does the soil feels very smooth with some grittiness?Does the soil feels very smooth with some grittiness? ------------

Silt loamSilt loam

Does not feel gritty or smooth?Does not feel gritty or smooth? ---------- LoamLoam


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Making a ribbonMaking a ribbon

The length of the ribbon will depend on

clay content and mineralogy.



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Question 4:Question 4: Does soil form a ribbon from 2.5Does soil form a ribbon from 2.5

to 5 cm?to 5 cm?

YesYes -- the possible textures are sandy clay loam,the possible textures are sandy clay loam,

silty clay loam, or clay loamsilty clay loam, or clay loam

Does the soil feel gritty?Does the soil feel gritty? -------------- Sandy Clay LoamSandy Clay Loam


Silty Clay LoamSilty Clay Loam

Does not feel gritty or smooth?Does not feel gritty or smooth? ---------- Clay LoamClay Loam


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Question 4:Question 4: Does soil form a ribbon > 5 cm?Does soil form a ribbon > 5 cm?

YesYes -- the possible textures are sandy clay,the possible textures are sandy clay,

silty clay, or claysilty clay, or clay

Does the soil feel gritty?Does the soil feel gritty? -------------- Sandy ClaySandy Clay


Silty ClaySilty Clay

Does not feel gritty or smooth?Does not feel gritty or smooth? ---------- ClayClay


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Forms a cast of moist soil material.

Textural class is LOAMY SAND



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Method 2: Estimating Sand andMethod 2: Estimating Sand and

Clay ContentClay Content

Collect a soil sample and remove theCollect a soil sample and remove theobservable the coarse fragments, organicobservable the coarse fragments, organicmaterial (roots, etc), and other materialsmaterial (roots, etc), and other materials

If sample is dry, moisten the sample. Do notIf sample is dry, moisten the sample. Do notover wet or completely saturate the sample.over wet or completely saturate the sample.

Knead sample between your thumb and fingerKnead sample between your thumb and finger

and remove any other coarse fragments or nonand remove any other coarse fragments or non--soil aggregates.soil aggregates.

Crush all the soil aggregates.Crush all the soil aggregates.


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Question 1: Does the soil have more thanQuestion 1: Does the soil have more than

50 % sand?50 % sand?

YesYes-- Therefore, the sand texture is dominant andTherefore, the sand texture is dominant and

the likely soil textures are sandy clay loam, sandythe likely soil textures are sandy clay loam, sandy

clay, sandy loam, loamy sand, and sand. materialclay, sandy loam, loamy sand, and sand. material

(roots, etc), and other materials.(roots, etc), and other materials.

NoNo Therefore, the sand does not dominate andTherefore, the sand does not dominate andthe likely soil textures are loam, silt loam, silt, claythe likely soil textures are loam, silt loam, silt, clay

loam, silty clay loam, silty clay, and clay.loam, silty clay loam, silty clay, and clay.


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> 50 %

< 50 %


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Question 2: What is the range in clay content and isQuestion 2: What is the range in clay content and is

the sand content > 20 %?the sand content > 20 %?

The key is ribbon length and sand percentage.The key is ribbon length and sand percentage.

Ribbon < 1 inch longRibbon < 1 inch long texture does not include the wordtexture does not include the wordclay. (sand, loamy sand, sandy loam, loam, silt loam, andclay. (sand, loamy sand, sandy loam, loam, silt loam, and

silt)silt)

Ribbon 1 to 2.5 inch (clay is 27 to 40 %), the soil textureRibbon 1 to 2.5 inch (clay is 27 to 40 %), the soil texture

includes the word clay. (sandy clay loam, clay loam, andincludes the word clay. (sandy clay loam, clay loam, andsilty clay loam)silty clay loam)

Ribbon > 2.5 inch (clay > 40%), clay is the dominant nameRibbon > 2.5 inch (clay > 40%), clay is the dominant name

in the soil texture. (sandy clay, silty clay, and clay)in the soil texture. (sandy clay, silty clay, and clay)


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Ribbon > 2.5 inches

Ribbon 1 to 2.5 inches

Ribbon < 1 inch


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Combine Your ObservationsCombine Your Observations

Sand content < 50 %Sand content < 50 %

Ribbons 1.5 inchRibbons 1.5 inch

Material has more of a floury feel and no realMaterial has more of a floury feel and no real

gritty feel. Sand content is likely under 20 %gritty feel. Sand content is likely under 20 %

When near saturated the material is sl. sticky.When near saturated the material is sl. sticky.

Therefore, the field evaluation would suggest that the soil has a

clay modifier. It is likely that the soil is a silty clay loam.


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Method 4Method 4 Hydrometer MethodHydrometer Method

The Bouyoucos hydrometer method of mechanical analysis used in routine work,

where quick measurements are necessary and extreme accuracy is not required.

The method is based on the fact that water containing material in suspension has greater

density than pure water. The more material in suspension, the greater the density.

The Bouyoucos hydrometer measures the density of the suspension. The higher the

hydrometer floats, the greater the density of the suspension.

Requirements:

1) Hydrometer- reading in grams

2) Electronic Balance

3) Dry Soil 40 to 60 grams4) Dispersing Agent

5) Use of an Oxidizing Agent (H202)

6) 1000 ml volumetric cylinder

7) Readings at 40 seconds and 3 hours

8) Temperature Correction


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Method 5Method 5 --Sieve AnalysisSieve Analysis

ParticleParticle--Size DistributionSize Distribution

Particle size distribution describes the abundance (byParticle size distribution describes the abundance (by

weight) of the various size particles that constitute theweight) of the various size particles that constitute the

mineral portion of soil materials.mineral portion of soil materials.

The distribution of the size based on mm, pH #, orThe distribution of the size based on mm, pH #, orsieze size is used for more detailed geological,sieze size is used for more detailed geological,

engineering, and geotechnical applications.engineering, and geotechnical applications.

Distribution of Particles for (Sand) can be used toDistribution of Particles for (Sand) can be used to

estimate the permeability using the Hazen equations.estimate the permeability using the Hazen equations.

Laboratory MethodLaboratory Method


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Method 6Method 6 Pipette MethodPipette Method

The pipet method utilizes Stoke's Law by the extraction of subsamples of the

soil suspension at a given depth after a predetermined settling time for each size

fraction of interest.

As time passes, larger particles pass by the sampling depth, and smaller and

smaller size fractions can be sampled.

After extracting the sample, it is dried weighed, and a calculation can be done to

determine the percentage of the total soil in suspension present in each sample.

The pipet method is very accurate, but also time consuming. Pretreatment of

the sample may include the use of dispersing chemicals or oxidizing agents.V = (2gr)(d1-d2)/9 (Stokes Law)

Where,

V = velocity of fall (cm sec-), g = acceleration of gravity (cm sec-),

r = "equivalent" radius of particle (cm), dl = density of particle (g cm - ),

d2 = density of medium (g cm- ), and = viscosity of medium (dyne sec cm-).


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ReviewReview

The three soil separates are ?The three soil separates are ?

Mineral Particles Greater than 2 mm are?Mineral Particles Greater than 2 mm are?

Are all soil and textural classifications theAre all soil and textural classifications the

same?same?

sand, silt, and clay

Coarse Fragments or Rock Fragments

NO the classification systems are not the same !


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Presented by:Presented by:

Mr. Brian Oram, PG, PASEOMr. Brian Oram, PG, PASEOWilkes UniversityWilkes University

GeoEnvironmental Sciences andGeoEnvironmental Sciences and

Environmental Engineering DepartmentEnvironmental Engineering Department

WilkesWilkes -- Barre, PA 18766Barre, PA 18766570570--408408--46194619

http://www.waterhttp://www.water--research.netresearch.net

know your soil powerpoint

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