Transcript Diagnostic Horizons - University of Florida

Soil Taxonomy and Classification
Soil Taxonomy Hierarchy
Order
12
Suborder
63
Great group
250
Sub group
1400
Family
8000
Series
19,000
Kingdom
Phylum
Class
Order
Family
Genus
Species
Diagnostic Surface Horizons
Epipedons
Mollic
Umbric
Ochric
Histic
Melanic
Plaggen
Anthropic
Very common
“specialized”
Human-derived
Organic Matter Accumulation
O.M. accumulation
Histic
Mollic, Umbric
ochric
time
Parent
material
Vegetation
established
tmax = 3000 yrs
Diagnostic Sub-surface Horizons
Diagnostic Subsurface Horizons
Formation
Translocation
Transformation
Clays
Organic Matter
Oxides
Subsurface Horizons
Organic Matter
Clays
Dark colors
Metals (Fe, Al)
smectites
Kaolinite
Formation
Translocation
Transformation
Oxides
Iron
Aluminum
Also: salts, carbonates, sulfides
Diagnostic Subsurface
Horizons
Albic
Argillic
Spodic
Oxic
Kandic
Cambic
Sombric
sulfuric
Natric
Agric
Calcic
Gypsic
Salic
Duripan
Fragipan
Placic
Subordinate Distinctions
Diagnostic Subsurface Horizons
Albic (white) Horizon
Light-colored (Value > 6 moist )
Elluvial (E master horizon*)
Low in clay, Fe and Al oxides
Generally sandy textured
Low chemical reactivity (low CEC)
Typically overlies Bh or Bt horizons
*not all E horizons are albic horizons
albic
Diagnostic Subsurface Horizons
Argillic Horizon
Illuvial accumulation of silicate clays
Illuvial based on overlying horizon
Clay bridges
Clay coatings
Bt horizon
Diagnostic Subsurface Clay Horizons
Argillic Horizon
High
Necessary
Kandic Horizon
Activity of Clays
Illuviation of clay
Low
Not Necessary
Diagnostic Subsurface Horizons
Spodic Horizon
• Illuvial accumulation of organic matter
and aluminum (+/- iron)
• Dark colored (value, chroma < 3)
• Low base saturation (acidic)
• Formed under humid acid conditions
Bh horizon
Spodic
Elluviation and Illuviation
Elluviation (E horizon and A horizons)
Organic matter
Clays
A
A
E
E
Bh horizon
Bt horizon
Bt
Bh
Spodic horizon
Argillic horizon
Diagnostic Subsurface Horizons
Oxic horizon
• Highly weathered (high temperatures, high rainfall)
- High in Fe, Al oxides
activity
- High in low-activity clays (kaolinite < smectite < vermiculite)
Bo horizon
Diagnostic Horizons
Surface Horizons:
Mollic- thick, dark colored, high %B.S., structure
Umbric – same, but lower B.S.
Ochric – pale, low O.M., thin
Histic – High O.M., thick, wet, dark
Sub-Surface Horizons:
Argillic – illuvial accum. of clay (high activity)
Kandic – accum. of clay (low activity)
Spodic – Illuvial O.M. accumulation (Al and/or Fe)
Oxic – highly weathered, kaolinite, Fe and Al oxides
Albic – light colored, elluvial, low reactivity
Soil Taxonomy
Diagnostic Epipedons
Diagnostic Subsurface horizons
Moisture Regimes
Temperature Regimes
Age
Texture
Depth
Soil Orders
Order
Suborder
Great group
12
63
250
Sub group
1400
Family
8000
Series
19,000
Soil forming processes, presence or
Absence of major diagnostic horizons
Similar genesis
Grasslands – thick, dark
epipedons
High %B.S.
Soil Orders
Entisols
Histosols
Inceptisols
Andisols
Gelisols
Alfisols
Mollisols
Ultisols
Spodosols
Aridisols
Vertisols
Oxisols
Soil Orders
Entisol
Histosol
Inceptisol
Alfisol
Ultisol
Spodosol
Mollisol
EntHistInceptAlfUltSpodMoll-
Recent
Histic (organic)
Inception
Television alien
Ultimate
Spodos (wood ash)
Mollis (soft)
Oxisol
Andisol
Gelisol
Aridisol
Vertisol
OxAndGelAridVert-
oxide
Ando (black)
Gelid (cold)
Arid (dry)
Verto (turn)
Soil Orders in Florida
•Entisols – little development, usually A-C horizons, ochric epipedon
•Inceptisols – A little more development, Bw horizons, ochric, umbric epipedon
•Alfisols – Argillic/Kandic horizon (Bt) less than 2 m, base saturation is > 35%
•Ultisols – Argillic/Kandic horizon (Bt) less than 2 m, base saturation is < 35%
•Mollisols – Mollic epipedon, dark, high organic matter
•Spodosols – Spodic horizon (Bh), ochric, umbric epipedon
•Histosols – Organic soil, histic epipedon
Entisols Inceptisols Alfisols
0
A
A
A
meters
E
Bw
A
A
E
Bt
C
Mollisols
Spodosols Histosols
A
E
O
Bw
Bh
C
C
Bt
C
C
2
Ultisols
C
Entisols
Young Soils
Weaklly developed
Sandy or clayey
Ochric Epipedon
A – C profiles
Taxonomic Peculiarity
A horizon
2 meters
(200 cm)
C horizon
Bt
Entisols
Inceptisols
Ap horizon
Little Development
Ochric, Histic, or Umbric epipedon
One or more subsurface horizons
Weakly developed
Contains many unweathered minerals
Bw horizon
C horizon
Histosols
•
•
•
•
•
Peat or muck
> 20% organic matter
Agriculturally valuable
Sometimes used as fuel
Often over impermeable material
Histosols
Alfisols
Mollic/Umbric/Ochric epipedon
A horizon
E horizon
Bt horizon (argillic, kandic)
base saturation > 35%
Btg horizon
Ultisols
A horizon
E horizon
Bt horizon
Mollic/umbric/Ochric epipedon
Argillic or Kandic horizon
Base saturation < 35%
Ultisols and Alfisols
Mixed Hardwood Forests
Spodosols
Associated with acidic vegetation
Subsoil accumulation of organic matter
with aluminum and/or iron
Formed under Wet acidic conditions
Poorly or Very poorly drained
Pine Flatwoods
State Soil of Florida
Spodosols
Pine Flatwoods (wet, acidic)
Mollisols
Mollic Epipedon
High organic matter
Thick surface horizon
Highly productive
Many with argillic
Poorly-drained
Surface % B.S. > 50%
Mollisols
Grasslands
Soil Orders
Weathering and
development
slight
Entisols
Histosols Inceptisols Andisols Gelisols
Aridisols Vertisols
Alfisols Mollisols
Ultisols Spodosols
Strong
Oxisols
Geographic Distribution
Florida Soil Orders
Spodosols
8.4 million acres
Entisols
7.5
Ultisols
6.9
Alfisols
4.6
Histisols
4.0
Inceptisols
1.0
Mollisols
1.0
Soil Taxonomy
Order
12
Soil forming processes / diagnostic horizons
Suborder
63
Great group
250
Sub group
1400
Family
8000
Series
19,000
Genetic similarity: Wetness, climate, vegetation
Moisture Conditions
Wet
Aquic – poor aeration, reduced iron
Udic- dry < 90 total days
Ustic - limited but is present
Aridic- moist <90 total days
Xeric - dry
Dry
Temperature Conditions
cold
Hot
Cryic – icy cold
Frigid – lower than 8oC
Mesic – between 8 and 15oC
Thermic – between 15 and 22oC
Hyperthermic - > 22oC
Suborders
Temperature, moisture, diagnostic horizons
Suborder Examples
Aquod
Udult
Udoll
Xeroll
Ochrept
Umbrept
alboll
very wet spodosol
wet ultisol
wet mollisol
dry mollisol
Soil Taxonomy
Order
Suborder
12
63
Great group
250
Sub group
1400
Family
8000
Series
19,000
Soil forming processes / diagnostic horizons
Soil moisture conditions, diagnostic horizon
Arrangement of Diagnostic horizons
Great Groups
Based on diagnostic horizons
and their arrangements or
other features like age, color, texture
Arg - argillic horizon present
Pale - old
Kand - kandic horizon present
Hapl - minimum horizonation
quartzi – quartz sand
Hum - humid
Greater Specificity
Order
Suborder
Great Group
Ultisol
Udult
paleudult
Mollisol
Aquoll
argiaquoll
Alfisol
Udalf
paleudalf
Ultisol
Udult
hapludult
Sub group
Expresses the core concept of the great group
Moisture, sandiness, depth, color
Typic
Arenic
Grossarenic
Aquic
shallow sand
deeper sand
deep sand
Typic hapludult
Grossarenic quartzipsamment
Subgroup
Great
group
suborder
order
Families
Properties important to growth of plant roots
Particle size
mineralogy
Sandy
Loamy
Fine loamy
Clayey
Siliceous
Kaolinitic
Smectitic
Oxidic
temperature oC
Frigid < 8
Mesic 8-15
Thermic 15-22
Hyperthermic > 22
Series
Horizon number, order, thickness, texture, structure,
Color, Organic matter, pH, accumulations
Order
Mollisol
Sub-order G. Group
Aquoll
Argiaqoll
Sub-group
typic Argiaquoll
Family
typic argiaquoll
loamy siliceous
Series
Brookston
Cordova
Westland
Alachua County
Apopka loamy, siliceous, hyperthermic grossarenic paleudult
Ledwith fine, smectitic, hyperthermic mollic albaqualf
Surrency loamy, siliceous, thermic, arenic paleaquult
Pomona sandy, siliceous, hyperthermic, ultic, haplaquod
paleudult
order
Suborder
great group
sub-group
family
albaqualf
paleaquult
haplaquod
Alachua County
paleudult
Great group suborder order
albaqualf
Great group
suborder
order