Soil Taxonomy and Classification

Soil Taxonomy Hierarchy Kingdom Phylum Class Order Family Genus Species Order Suborder Great group Sub group Family Series 12 63 250 1400 8000 19,000

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 Oxides Formation Translocation Transformation Subsurface Horizons Organic Matter Clays Oxides Dark colors Metals (Fe, Al) smectites Iron Aluminum Kaolinite 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 albic *not all E horizons are albic horizons

Diagnostic Subsurface Horizons Argillic Horizon Illuvial accumulation of silicate clays Illuvial based on overlying horizon Clay bridges Clay coatings Bt horizon Accumulation based on absolute increases compared to relevant horizon above or below. Argillic horizon. An argillic horizon is an illuvial horizon in which layer-silicate clays have accumulated to a significant extent by illuviation. They have formed below the surface of a mineral soil but may be exposed at the surface by erosion. In general, this is a B horizon which has an increase in clay content of at least 1.2 times that of the eluvial horizon above and is, in general, parallel to the surface of the polypedon. This increase of 20% in clay content occurs most in soils within a vertical distance of less than 30 cm. In case of clayey soils, this requirement would be unreasonable. If the surface horizon is greater than 40% clay, the increase of clay needed is only 8%. For sandy soils with less than 15% clay, an increase of 3% is required for meeting the criteria of an argillic horizon. In other words, if the clay content of the eluvial horizon is between 15 and 40%, an increase in clay of 20% is needed to meet the requirements for an argillic horizon.

Diagnostic Subsurface Clay Horizons Argillic Horizon Kandic Horizon High Low Activity of Clays Necessary Illuviation of clay 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 Bt A E Bh E Bh horizon Bt horizon Spodic horizon Argillic horizon

Diagnostic Subsurface Horizons Oxic horizon Highly weathered (high temperatures, high rainfall) - High in Fe, Al oxides - High in low-activity clays (kaolinite < smectite < vermiculite) activity 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

Diagnostic Subsurface horizons Soil Taxonomy Diagnostic Epipedons Diagnostic Subsurface horizons Moisture Regimes Temperature Regimes Age Texture Depth

Soil Orders Order 12 Suborder Great group 63 Sub group Family 250 Soil forming processes, presence or Absence of major diagnostic horizons Similar genesis Order Suborder Great group Sub group Family Series 12 63 Grasslands – thick, dark epipedons High %B.S. 250 1400 8000 19,000

Soil Orders Entisols Histosols Inceptisols Andisols Gelisols Alfisols Mollisols Ultisols Spodosols Aridisols Vertisols Oxisols

Soil Orders Entisol Histosol Inceptisol Alfisol Ultisol Spodosol Mollisol Oxisol Andisol Gelisol Aridisol Vertisol Ent- Hist- Incept- Alf- Ult- Spod- Moll- Ox- And- Gel- Arid- Vert- Recent Histic (organic) Inception Television alien Ultimate Spodos (wood ash) Mollis (soft) 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 Ultisols Mollisols Spodosols Histosols A A A A A O A E C Bw E E Bt Bw meters Bt Bh C C C C C 2

Entisols Young Soils Weaklly developed Sandy or clayey Ochric Epipedon A – C profiles

Taxonomic Peculiarity A horizon C horizon 2 meters (200 cm) Bt

Entisols

Inceptisols Little Development Ochric, Histic, or Umbric epipedon 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 State Soil of Florida 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 Many with argillic Poorly-drained Surface % B.S. > 50% Mollic Epipedon High organic matter Thick surface horizon Highly productive Many with argillic Poorly-drained Surface % B.S. > 50%

Mollisols Grasslands

Soil Orders slight Entisols Histosols Inceptisols Andisols Gelisols Strong Weathering and development Entisols Histosols Inceptisols Andisols Gelisols Aridisols Vertisols Alfisols Mollisols Ultisols Spodosols 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 Suborder Great group 63 Sub group Family 250 Series 12 Soil forming processes / diagnostic horizons Genetic similarity: Wetness, climate, vegetation 63 250 1400 8000 19,000

Temperature Conditions Moisture Conditions Wet Dry Aquic – poor aeration, reduced iron Udic- dry < 90 total days Ustic - limited but is present Aridic- moist <90 total days Xeric - 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 very wet spodosol Udult wet ultisol Udoll wet mollisol Xeroll dry mollisol Ochrept Umbrept alboll

Soil Taxonomy Order 12 Suborder Great group 63 Sub group Family 250 Series 12 Soil forming processes / diagnostic horizons Soil moisture conditions, diagnostic horizon Arrangement of Diagnostic horizons 63 250 1400 8000 19,000

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 Udult paleudult Aquoll argiaquoll Udalf paleudalf Udult hapludult Ultisol Mollisol Alfisol

Sub group Moisture, sandiness, depth, color Typic shallow sand Expresses the core concept of the great group Moisture, sandiness, depth, color Typic shallow sand Arenic deeper sand Grossarenic deep sand Aquic Typic hapludult Grossarenic quartzipsamment Subgroup Great group suborder order

Families Particle size mineralogy temperature oC Sandy Loamy Properties important to growth of plant roots Particle size mineralogy temperature oC Sandy Loamy Fine loamy Clayey Siliceous Kaolinitic Smectitic Oxidic Frigid < 8 Mesic 8-15 Thermic 15-22 Hyperthermic > 22

Series Horizon number, order, thickness, texture, structure, Color, Organic matter, pH, accumulations Order Sub-order G. Group Sub-group Family Series Mollisol Aquoll Argiaqoll typic Argiaquoll typic argiaquoll Brookston loamy siliceous Cordova Westland

Alachua County paleudult order Suborder great group albaqualf 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