Download Soil Development

Lecture 5b, 6, & 7a:
Soils I, II, & III
Spring 2006
WVU GEOL 321 ((J.S. Kite)
Soil:
Assemblage of natural bodies on the
Earth’s surface (natural or artificial)
capable of supporting plant life outdoors
Pedon:
Area on Earth’s surface w/ single type of soil
Also: soil mapping unit.
Soil Development
Is a Function of 5 Factors
S = ƒ (Cl,O,R,P,T)
1.
2.
3.
4.
5.
Climate
Organisms
Relief
Parent material
Time
1
Factors of Soil Development
1. Climate
Temperature & Moisture Affect Eh &
Redox Reactions
Fe (Iron) Depletions
Gray Reduced Iron (Water-Logged)
Fe (Iron) Concentrations
Red “Mottles” of Oxidized Iron
(= Redoximorphic features)
Factors of Soil Development
2. Organisms Microorganisms (Bacteria, Fungi)
Decompose organic material into humus
Macroorganisms
Bioturbation by Trees, Worms, Crayfish,
Groundhogs, Gophers, Grizzly Bears
Organisms Supply material
Leaves (Conniferous vs. Deciduous Forests)
Roots (Grasslands)
Factors of Soil Development
3. Relief
Slope
Steep Slopes: Well Drained, Erosion
Low Slopes: Poorly Drained, Deposition
Aspect
Direction slope faces
affects temperature & moisture
2
Factors of Soil Development
4. Parent Material
Material from which soil develops
Types of Parent Material
Residual Soil = Residuum
Bedrock weathers in situ, on low
relief & little erosion
Parent Material, (cont.)
Colluvial
Transported by Gravity
Alluvial
Material Transported by Streams
Glacial
Transported by Glaciers
Eolian
Transported by Wind
Factors of Soil Development
5. Time Needed to Form Soils Depends on
Other Factors
Warm Climates Form Soil Faster Than Cold
Biological & Geochemical Reactions Act
2X Faster for Every 10oC Increase
Water = a ‘must’ in Pedochemical
Reactions, Translocation
Parent Material Affects Time to Form Soil
3
Increasing Soil Development
Soil Properties Through Time
Geometric
Logarithmic
Steady State
Increasing Time
Soil Characteristics
1. Color
Typically Formed by three substances
1. Humus
Decomposed organic material
2. Iron (Fe)
3. Carbonate
Munsell soil color chart
Soil Characteristics cont.
2. Texture (USDA)
= size of soil particles in “matrix”
Sand = 2.0 to 0.05 mm
Silt =
0.05 to 0.002 mm
Clay =
less than 0.002 mm
Excludes particles >2 mm
Loam = Significant percentage of all three
(2 sand: 2 silt: 1 clay)
4
Soil Characteristics cont.
Textural Triangle
Texture determined by two methods
1. Particle Size Analysis
Laboratory method
2. By Feel (Field method)
Takes lots of practice
High clay content will cause
soil to form ribbon when rolled.
20
30
80
S
nt
rce
Pe
Soil
Texture
Triangle
10
100
90
ilt
70
24 Jan 2006
50
40
Clay
60
50
yS
an
d
90
80
Silt
10
0
Sand
70
60
Pe
rce
n
tC
l ay
Silty
Clay
Silty Clay
Clay Loam
Loam
30 Sandy Clay
Loam
20
Loam
Silt Loam
10 Loam Sandy Loam
Sandy
Clay
40
10
20
30
40
50
60
70
80
90
0
10
Percent Sand
Soil Characteristics cont.
3. Soil Structure
PEDS: aggregates of
particles
Types of Structure
Blocky (well developed)
Platy
Prismatic
Columnar
Granular (high organics)
5
Soil Horizons
Soil Profile
Described from the surface down
Solum
“True soil”
= A &/or E & B horizons
Soil & Ground Water
Distribution
Eastern USA
• Soil Moisture Belt
• Unsaturated (= Vadose
= Aeration) Zone
Capillary Fringe
• Water Table
• Saturated
(= Phreatic) Zone
Soil & Ground Water
Distribution
Western USA
Phreatophytes
• Soil Moisture Belt
• Unsaturated (= Vadose =
Aeration) Zone
Capillary Fringe
• Water Table
• Saturated (Phreatic) Zone
6
Soil Horizons
Idealized Soil Profile
Surface
Solum =
A, E, and B
{
L Horizon Leaf Litter
O Horizon Decomposed Organics
A Horizon Top Soil
E Horizon Leached Horizon
B Horizon Subsoil
Weathered (?)
C Horizon Parent Material
R Horizon Bedrock
Soil Horizons cont.
L = New leaf litter
In forest soils
O = Organic Layer
Partly decomposed organic matter
A = Top Soil
Mix of inorganic & organic material
Eluvial horizon
Most fertile soil horizon
Soil Horizons cont.
E = Eluvial Horizon
Organics & minerals even more elluviated,
light color horizon
B = Subsoil
Illuvial horizon
High clay content?
Maximum soil development
7
Soil Horizons (cont.)
C = “Weathered” Parent Material or
“Unweathered” Transported Material
Has NOT undergone soil formation
R = Bedrock
Unweathered Bedrock
Diagnostic Horizons
EPIPEDONS
Mollic:
dark, > 1% O.M. in upper 7”, >50% base saturation
Ochric:
light, < 1% O.M.
Umbric:
dark, <50% base saturation
Histic:
peaty surface layer
Plaggen:
>20” of manure applied over long time
Diagnostic Horizons cont.
SUBSURFACE HORIZONS
Spodic: buildup of humus
Argillic: buildup of clay
Cambic: incomplete argillic or spodic horizon
Oxic: high clay, 1:1 clay, low CEC
Petrocalcic: Concentration of carbonates
Albic: light colored E horizon
Other Common Soil “Horizons”
Fragipan: brittle layer with high bulk density
Saprolite: soil mineralogy w/ relict bedrock structure
8
Fragipan:Top view of truncated soil - Canaan Valley
Btx horizon
J.S. Kite Photo
Fragipan: Side view showing reduced tongues
J.S. Kite Photo
Subdivisions of Horizons:
• A
• B
• B2
• B3
• BC
• 2 BC
• 2C
• 3C
“1” not written
Change in Parent Material
Change in Parent Material
9
lower case notations to horizons:
•
•
•
•
•
•
•
Ap
Bw
C
Ab
Bt
BC
C
p = disturbed (plowed?) A
w = incipient (weak) B
b = buried A
t = argillic clay build-up
Catena
Sequence of soils of about the same age,
derived from similar parent material, and
occurring under similar climate conditions,
but having different characteristics due to
variation in relief and in drainage.
SSSA Internet Glossary of Soil Science Terms
http://www.soils.org/sssagloss/
Catena, Alberta
www.soils.rr.ualberta.ca/soa/catena3.cfm
10
Soil and Soil Development
Soil Handout
Soil Taxonomy
6 Levels of Classification
Order
Suborder
Great Group
Subgroup
Family
Series
Soil Taxonomy
“Tucker County Mine Soil”
Loamy-skeletal, mixed, acid, frigid Typic Udorthent
ent = Entisol (ent as in recent) [Soil Order]
orth = Common (typical entisol) [Suborder]
Ud = Humid climate [Great Group]
Typic = Common (typical udorthent) [Subgroup]
frigid = Cold climate
acid = pH less than 4.0
mixed = mixed mineralogy of materials in the soil
skeletal = greater than 35% rock fragments in soil
Loamy = textural classification = LOAM
11
ORDER
FORMATIVE ELEMENT
Entisol
ent
no horizons
Inceptisol ept
incipient horizons - Cambic horizon
Alfisol
alf
argillic horizon, high B.S. >35%
Ultisol
ult
argillic horizon, low B.S. <35%
Oxisol
ox
oxic horizon
Mollisol
oll
mollic epidedon
Spodosol od
spodic horizon
Vertisol
ert
shrink-swell soils
Aridisol
id
dry >50% of year
Histosol
ist
>30% organic matter
Andisols
and tephras
Gelisols
el
permafrost
Suborder Formative Elements
•
•
•
•
•
Alb
Aqu
Arg
Ferr
etc.
-
White Albino
Wet
Argillic Horizon
Iron
Examples of Suborders
(2 Formative Elements):
•
•
•
•
•
Albolls Aquolls Rendolls Xerolls Borolls -
Albic Horizon
Wet (Aqueous)
Rendzina (Lots O. M. + Hi pH)
Xeric Dry Season
Boreal Cool
12
Mon-Marion County Soil
Survey
West Virginia
State Soil (1997)
feet
• See P. 157
Monongahela
Silt Loam
Fine-loamy, mixed,
semiactive, mesic
Typic Fragiudults
Source of image & text for 2 slides:
www.statlab.iastate.edu/soils/
photogal/statesoils/wv_soil.htm
Monongahela soils occur on >100,000
acres in 45 counties in West Virginia.
These very deep, moderately welldrained soils are on alluvial or glaciallake terraces (after NRCS w/ JSK modif.)
Generalized Distribution
13
TYPE LOCATION: 2.7 mi E of
Beverly, 100 ft N of church on N
boundary of 4-H Camp, Randolph
Co., WV;
MLRA OFFICE: Morgantown, WV
SERIES ESTABLISHED: Greene
County, Pennsylvania, 1921.
DIAGNOSTIC HORIZONS, etc.
Ochric epipedon - 0 to 12 inches
(Ap & BA horizons).
Argillic horizon - 12 to 22 inches
(Bt horizon).
Fragipan - 22 to 52 inches
(Btx horizon).
Source of image and text for 3 slides:
www.statlab.iastate.edu/soils/
osd/dat/M/MONONGAHELA.html
Ap--0 to 7 inches; dark grayish
brown (10YR 4/2) silt loam;
moderate fine granular
structure; friable; many
roots; slightly acid; abrupt
smooth boundary. (6 to 10
inches thick)
BA--7 to 12 inches; yellowish brown (10YR 5/4) silt loam; weak fine subangular
blocky structure; friable; common roots; slightly acid; clear smooth boundary. (0 to
7 inches thick)
Bt--12 to 22 inches; yellowish brown (10YR 5/6) silt loam; weak to moderate fine
subangular blocky structure; friable; common roots; few distinct clay films on faces
of peds; moderately acid; clear wavy boundary. (8 to 20 inches thick)
Btx1--22 to 31 inches; yellowish brown (10YR 5/4) loam; common fine distinct
yellowish brown (10YR 5/8) and light brownish gray (2.5Y 6/2) mottles; weak
coarse prismatic structure parting to weak coarse platy; firm; few distinct clay
films; very strongly acid; clear irregular boundary. (7 to 14 inches thick)
Btx2--31 to 42 inches; light yellowish brown (10YR 6/4) loam; many medium
distin\ct yellowish brown (10YR 5/8) and light brownish gray (2.5Y 6/2) mottles;
weak very coarse prismatic structure parting to weak coarse platy; very firm,
brittle; few distinct clay films; very strongly acid; clear wavy boundary. (8 to 15
inches thick) Btx3--42 to 52 inches; light yellowish brown (10YR 6/4) cobbly loam;
many distinct yellowish brown (10YR 5/8) and light brownish gray (2.5Y 6/2)
mottles; weak very coarse prismatic structure parting to weak coarse platy; very
firm,
brittle; few distinct clay films; numerous fine pores; 25 percent sandstones
cobbles; very strongly acid; clear wavy boundary. (0 to 12 inches thick)
C--52 to 65 inches; mixed strong brown (7.5YR 5/8) and light gray (N 7/ ) clay
loam, pale yellow (2.5Y 7/4) crushed massive; firm; 35 percent weathered shale,
sandstone fragments and cobbles; very strongly acid; clear smooth boundary.
Ap--0 to 7 inches; dark grayish brown (10YR 4/2) silt loam; moderate fine
granular structure; friable; many roots; slightly acid; abrupt smooth
boundary. (6 to 10 inches thick)
BA--7 to 12 inches; yellowish
brown (10YR 5/4) silt loam;
weak fine subangular blocky
structure; friable; common
roots; slightly acid; clear
smooth boundary. (0 to 7
inches thick)
Bt--12 to 22 inches; yellowish brown (10YR 5/6) silt loam; weak to moderate fine
subangular blocky structure; friable; common roots; few distinct clay films on faces
of peds; moderately acid; clear wavy boundary. (8 to 20 inches thick)
Btx1--22 to 31 inches; yellowish brown (10YR 5/4) loam; common fine distinct
yellowish brown (10YR 5/8) and light brownish gray (2.5Y 6/2) mottles; weak
coarse prismatic structure parting to weak coarse platy; firm; few distinct clay
films; very strongly acid; clear irregular boundary. (7 to 14 inches thick)
Btx2--31 to 42 inches; light yellowish brown (10YR 6/4) loam; many medium
distinct yellowish brown (10YR 5/8) and light brownish gray (2.5Y 6/2) mottles;
weak very coarse prismatic structure parting to weak coarse platy; very firm,
brittle; few distinct clay films; very strongly acid; clear wavy boundary. (8 to 15
inches thick) Btx3--42 to 52 inches; light yellowish brown (10YR 6/4) cobbly loam;
many distinct yellowish brown (10YR 5/8) and light brownish gray (2.5Y 6/2)
mottles; weak very coarse prismatic structure parting to weak coarse platy; very
firm,
brittle; few distinct clay films; numerous fine pores; 25 percent sandstones
cobbles; very strongly acid; clear wavy boundary. (0 to 12 inches thick)
C--52 to 65 inches; mixed strong brown (7.5YR 5/8) and light gray (N 7/ ) clay
loam, pale yellow (2.5Y 7/4) crushed massive; firm; 35 percent weathered shale,
sandstone fragments and cobbles; very strongly acid; clear smooth boundary.
14
Ap--0 to 7 inches; dark grayish brown (10YR 4/2) silt loam; moderate fine
granular structure; friable; many roots; slightly acid; abrupt smooth
boundary. (6 to 10 inches thick)
BA--7 to 12 inches; yellowish brown (10YR 5/4) silt loam; weak fine subangular
blocky structure; friable; common roots; slightly acid; clear smooth boundary.
(0 to 7 inches thick)
Bt--12 to 22 inches; yellowish brown (10YR 5/6) silt loam; weak to moderate fine
subangular blocky structure; friable; common roots; few distinct clay films on
faces of peds; moderately acid; clear wavy boundary. (8 to 20 inches thick)
Btx1--22 to 31 inches; yellowish
brown (10YR 5/4) loam; common
fine distinct yellowish brown (10YR
5/8) and light brownish gray (2.5Y
6/2) mottles; weak coarse prismatic
structure parting to weak coarse
platy; firm; few distinct clay films;
very strongly acid; clear irregular
boundary. (7 to 14 inches thick)
Btx2--31 to 42 inches; light yellowish brown (10YR 6/4) loam; many medium
distinct yellowish brown (10YR 5/8) and light brownish gray (2.5Y 6/2) mottles;
weak very coarse prismatic structure parting to weak coarse platy; very firm,
brittle; few distinct clay films; very strongly acid; clear wavy boundary. (8 to 15
inches thick) Btx3--42 to 52 inches; light yellowish brown (10YR 6/4) cobbly loam;
many distinct yellowish brown (10YR 5/8) and light brownish gray (2.5Y 6/2)
mottles; weak very coarse prismatic structure parting to weak coarse platy; very
firm,
brittle; few distinct clay films; numerous fine pores; 25 percent sandstones
cobbles; very strongly acid; clear wavy boundary. (0 to 12 inches thick)
C--52 to 65 inches; mixed strong brown (7.5YR 5/8) and light gray (N 7/ ) clay
loam, pale yellow (2.5Y 7/4) crushed massive; firm; 35 percent weathered shale,
sandstone fragments and cobbles; very strongly acid; clear smooth boundary.
Distribution of Soil Orders
The distribution of Soil Orders depends
on all of the 5 factors of soil formation
S = ƒ (Cl,O,R,P,T)
Climate has the most influence on a
global or continental scale
Climate
Climate
Soil Orders
15
Soil Orders - USA
Soil Orders.
Entisols
“Ent” For Recent;
Very Little
Development
New Surficial
Deposits
Soil Orders cont.
Inceptisols
“Incept” for inception
Cambic Horizon
16
Soil Orders cont.
Alfisols
“Alf” for Aluminum ‘Al’ and Iron ‘Fe’
Argillic horizon, high (>35%) base
saturation
Well-developed soil
Common West Virginia soil
Alfisol
Wisconsin
J.S. Kite Photo
Soil Orders cont.
Ultisols
“Ult” for ultimate
Highly weathered, but less than Oxisols
Argillic horizon & low (<35%) base saturation
Dominant soil type in SE USA
17
Ultisol
http://www.statlab.iastate.edu/
soils/photogal/orders/soiord.htm
Ultisol
Shenandoah Valley, Virginia
70 ft
J.S. Kite Photo
Soil Orders, cont.
Oxisols
“oxi” for oxides
Red soils due to oxidized iron
Highly weathered
Warm, moist tropics
18
Oxisol
Oxisol
Cornfield
Mollisol
Shenandoah Valley,
Virginia
J.S. Kite Photo
19
Mollisol
Great Plains
Calcite
Soil Orders cont.
Spodosols
Light-colored E horizon & Dark
illuvial B horizon
Mostly loamy to sandy soils
Common in acidic soils of
coniferous forests organic acids aid translocation
Spodosols at high elevation in WV
J.S. Kite Photo
Spodosol
Allagash River
Terrace, Maine
20
Soil Orders cont.
Vertisols
“Vert” for invert
Contain smectite
Shrink-swell properties causes Turnover
Slickensides, “Tee-pee” Structures
Texas Gulf Coast
Vertisol, Zambia
Soil Orders cont.
Aridisols
Dryland Soils
Highly alkaline (high pH),
commonly saline
Typical in SW U.S.
21
Aridisol
Soil Orders cont.
Histosols
“Hist” means fiber
Dark, organic soils
May be muck or peat
Anaerobic, Negative Eh
Highly acidic
Histosol, Carrying Place Bog, Maine
J.S. Kite Photo
22
New (1998) Soil Orders
Andisols
Soils in Tephras
Gelisols
Soils Under Permafrost)
Andisol
Aquic Vitrixerands
Washington
http://www.statlab.iastate.
edu/soils/photogal/
statesoils/wa_soil.htm
J.S. Kite Photo
Gelisol: Victoria Valley, Antarctica
23
Gelisol
http://www.statlab.iastate.edu/
soils/photogal/orders/soiord.htm
Proposed Soil Order
Anthrosols
Proposed soil order for artificially
disturbed material
24