l05a

Lecture 5aSoil Taxonomy : 

Lecture 5a Soil Taxonomy Purpose of Soil Taxonomy: 1. Organize knowledge about soils 2. Understand relationships among different soils 3. Establish groups or classes for practical purposes. a. predicting behavior b. identifying best uses c. estimating productivity d. extending research results

Soil Taxonomy: 

Soil Taxonomy Soils are classified into into six categories based on diagnostic characteristics The last category will place the soils into one of the 12 Soil Orders.

Soil Taxonomy: 

Soil Taxonomy Orders (12) Suborders (54) Great Groups (211) Subgroups (1,100+) Family (7,000+) Series (a lot!) Fine-loamy mixed, superactive, mesic Aquic Argiudolls Large Category Small Category

Orders: 

Orders Highest and most general of the soil classification system (similar to the phylum in plant taxonomy) Based on conditions under which the soil developed Fine-loamy mixed, superactive, mesic Aquic Argiudolls Order oll = Mollisols

Suborders: 

Suborders Grouped by similarities in soil formation such as wetter/dryer soil, colder/warmer soil, etc. Fine-loamy mixed, superactive, mesic Aquic Argiudolls Ud = Udic Moisture

Great Groups: 

Great Groups Based on differences between soil horizons Fine-loamy mixed, superactive, mesic Aquic Argiudolls Great Group Sub Order Order Argi = Clay accumulation

Sub Groups: 

Sub Groups Describes a profile characteristic, wetness, sand, tonguing of E, etc. Great Group Fine-loamy mixed, superactive, mesic Aquic Argiudolls Sub Group Sub Order Order Aquic = wet soil

Family: 

Family Based on soil properties that affect management and root penetration, such as texture, temperature, and depth Great Group Fine-loamy, mixed, superactive, mesic Aquic Argiudolls Family Sub Group Sub Order Order Texture, clay minerals, CEC, temp,

Series = Le Sueur : 

Series = Le Sueur Named from the town or landscape feature near where the soil was first recognized (Lester = Lester Prairie, MN. Other examples = Clarion, Nashwauk, Milaca, Port Byron, Zimmerman. Le Sueur for Le Sueur County, MN.) Great Group Fine-loamy mixed, superactive, mesic Aquic Argiudolls Family Sub Group Sub Order Order

Diagnostics Horizons- Used to place soils in the 6 categories: 

Diagnostics Horizons- Used to place soils in the 6 categories Surface (Epipedon) Mollic Umbric Histic Ochric Subsurface Argillic Natric Spodic Oxic Cambic None

Soil Taxonomy- Diagnostic Surface Epipedons: 

Soil Taxonomy- Diagnostic Surface Epipedons Mollic Epipedon - thick, dark, soft, surface layer. Characteristics Thick - greater than 10 inches; High base saturation> 50%; Mineral soil Soils formed under prairie vegetation

Other Epipedons: 

Other Epipedons Umbric - like mollic, but low base saturation Histic - Organic Soil - saturated with water, > -% organic matter Ochric - thin, light colored - surface layers that do not fit any of the above

Comparison of Epipedons: 

Comparison of Epipedons

Diagnostic Subsurface Horizons: 

Diagnostic Subsurface Horizons Argillic - illuvial horizon of clay accumulation - Bt Natric - same as argillic but with > 15% exchangeable sodium (Na) - Btn

Diagnostic Subsurface Horizons: 

Diagnostic Subsurface Horizons Spodic - illuvial accumulation of oxides of Al and Fe (sesquioxides) and OM, red or dark red color - only found in acid sandy soils, with high rainfall- generally found below E horizon. Contains a Bhs or Bs horizon Oi E Bhs Bs C

subsurface horizons (cont.): 

subsurface horizons (cont.) Oxic - very weathered layer of only Fe and Al oxides and 1:1 clay minerals, low pH and not very fertile (found in tropical soils) Bo Cambic - slightly altered layer - not weathered enough to be argillic, Bw horizon designation or development of color and or structure NONE - no diagnostic subsurface horizon present

Comparison of Subsurface Diagnostic Horizons: 

Comparison of Subsurface Diagnostic Horizons Oxic very weathered Spodic Cambic Argillic Natric more Al and Fe less developed more sodium

12 Soil Orders - Each Order has a diagnostic epipedon and subsurface horizons – which could be “none”. WEB SITE for soil orders = www.mines.uidaho.edu/pses/teach_res: 

12 Soil Orders - Each Order has a diagnostic epipedon and subsurface horizons – which could be “none”. WEB SITE for soil orders = www.mines.uidaho.edu/pses/teach_res Entisol Inceptisol Andisols Spodosols Mollisols Alfisols Ultisols Oxisols Aridisols Vertisols Histosols Gelisols

Entisol - ent: 

Entisol - ent Recent soils - minimal development, little horizonation, young soils. 12.5% of world, Ochric + none

Entisol - Idaho: 

Entisol - Idaho A R

Vertisol - ert: 

Vertisol - ert Inverted - soils with high clay content, large shrink swell potential - gradually invert on themselves, 2.1% of the world, Mollic or Ochric + none

Vertisol = Bss at slickenslide: 

Vertisol = Bss at slickenslide

Inceptisol - ept: 

Inceptisol - ept Inception - soil shows the beginning of horizon development, little or no illuviation, 15.8% of world, Ochric or Umbric + cambic.

Inceptisol: 

Inceptisol Soil Formed in colluvial material in mountains of Idaho.

Aridisols - id: 

Aridisols - id Arid regions of the world (19%), < 10 in. of rainfall, usually contain carbonates, Ochric + cambic or argillic or other diagnostic feature. A Bw Bk C

Aridisol in Idaho: 

Aridisol in Idaho A Bt Bk Bkqm R

Aridisol - Nevada: 

Aridisol - Nevada Az Bz C1 C2 NaCl Salt accumulates on the surface and in the subsurface.

Mollisols - oll: 

Mollisols - oll soils with thick, dark, soft surface - mollic + cambic, natric, argillic or none - high base saturation - soils of the prairie 9% of the world

Mollisol: 

Mollisol This mollisol formed in a new parent material (loess) that buried the original soil soil -the Btb (b = buried). Mollisol from Kansas that is developed in Limestone bedrock. A1 A2 Bw BC R

Spodosols- od: 

Spodosols- od acid sandy soils with thick E and red Bhs - ochric and spodic - 5.4 % of the world - infertile soils. Oi E Bhs Bs C

Alfisol -- alf: 

Alfisol -- alf fertile forested soils with ochric and argillic - high base saturation (> 35%) - forested soils 7% of the world.

Ultisols - ult: 

Ultisols - ult soils more weathered than Alfisols - ochric and argillic - low base saturation < 35% - redder and more acid than Alfisols 8.5% of the world - less fertile than Alfisols A E Bt1 Bt2 BC

Alfisol & Ultisol: 

Alfisol & Ultisol

Histosols - ist: 

Histosols - ist peat soils - organic material - histic 0.8% of the world Histic Epipedon. Oe1 Oe2 Oe3 Oe4 Oa 2C Photo USDA

Dyad: 

Dyad Describe the Soil Order that is most likely found in your home town.

Andisols - and: 

Andisols - and soils from volcanic ash - very light - low bulk density -- 1% or the world Andisol from Idaho A Bw 2BC 2C A Bw Ab Bwb Ab’

Oxisols - ox: 

Oxisols - ox Soils with Oxic horizon - very weathered - soils of the tropics. low pH - acid soils - high in 1:1 clay minerals 9.2% of world

Oxisol: 

Oxisol Ap1 Ap2 Bo1 Bo2 Bo3

Oxisol Puerto Rico: 

Oxisol Puerto Rico Ap A Bo1 Bo2 BC C

Gelisol - el: 

Gelisol - el New Order as of 1998 - soils with permafrost (formerly Cryochrepts - or frozen Inceptisols) Cf - horizon

Soil Orders USA: 

Soil Orders USA

Soil Orders in Minnesota: 

Soil Orders in Minnesota

Soil Orders – Wisconsin & Northern Illinois: 

Soil Orders – Wisconsin & Northern Illinois

Soil Suborders of Minnesota: 

Soil Suborders of Minnesota Mollisol - Udoll - Boroll - Aquoll - Ustoll Alfisol - Udalf - Boralf - Aqualf Dropped in 1998 Entisol - Orthent - Psamment – Aquent - Fluvent Inceptisol - Udept - Aquept Spodosol - Orthod Vertisol - Aquert Histosol - Fibrist - Hemist - Saprist

Suborder definitions: 

Suborder definitions Ud - Udic moisture = moist -southern Mn type climate & Us = Ustic = Dry Bor - Boreas = northern Mn. Climate (Frigid Temperature regime) Aqu - Aquic moisture = saturated soil - high water table - Gleyed conditions Orth - true or simple - regular Entisols & Spodosols Psamm - sand - sandy Entisols Fluv - floodplain –irregular Organic matter

Udoll - Ustoll - Aquoll: 

Udoll - Ustoll - Aquoll Ustoll

Udalf - Boralf - Aqualf: 

Udalf - Boralf - Aqualf

Orthent - Psamment – Aquent - Fluvent: 

Orthent - Psamment – Aquent - Fluvent A Bw C Orthent Not Cambic due to being too sandy

Slide49: 

Fluvent – Soils of the floodplains. Lots of layers that are deposited when the river floods

Orthod: 

Orthod Wisconsin Orthod A E Bhs Bs C Minnesota Orthod

Udept - Aquept: 

Udept - Aquept EUTRUDEPTS

Aquert: 

Aquert

Fibrist - Hemist - Saprist: 

Fibrist - Hemist - Saprist

Suborder Map: 

Suborder Map You need to know the location of the suborders in Minnesota