Soil Orders Study Guide – Part II These slides are to help organize in your mind: Key features for each Soil Order See also – Soil Orders Study Guide – Part I (on course website) and the text for the orders’ - key diagnostic features, arranged into keys (another key is also given in last slides in this Part) developmental progression Info on diagnostic surface & subsurface layers

Soil Taxonomy Order

Taxonomy: The Basics All soils belong to one of the 12 soil ORDERS, which are differentiated from each other primarily by the presence or absence of specific diagnostic horizons. The order names all end in “sol” See also: http://soils.ag.uidaho.edu/soilorders

Soil Orders Soil Order Ending Characteristics, location, etc. Entisol Absence of distinct pedogenic horizons; climate & PM key factors Inceptisol -ept Gelisol -el Histosol -ist Andisol -and Aridisol -id

Entisols

Soil Orders Soil Order Ending Characteristics, location, etc. Entisol -ent Absence of distinct pedogenic horizons; climate & PM Inceptisol -ept Weak development, nothing exciting. There is a “B” horizon Gelisol -el Histosol -ist Andisol -and Aridisol -id

Inceptisols A 0 –5 cm AB 5- 18 Bw1 18 - 33 Bw2 33 - 55 BC 55 - 76

Soil Orders Soil Order Ending Characteristics, location, etc. Gelisol Entisol -ent Absence of pedogenic horizons Inceptisol -ept Weak development Gelisol -el Permafrost, freeze-thaw features (13% of soils worldwide!) Histosol -ist Andisol -and Aridisol -id

Gelisols This is a test of notes feature

Gelisols

Soil Orders Soil Order Ending Characteristics, location, etc. Histosol Entisol -ent Absence of distinct pedogenic horizons Inceptisol -ept Weak development Gelisol -el Permafrost, freeze-thaw Histosol -ist Very high OM in upper 80 cm (peats), wet Andisol -and Aridisol -id

Histosols

Soil Orders Soil Order Ending Characteristics, location, etc. Andisol Entisol -ent Absence of horizons Inceptisol -ept Weak development Gelisol -el Permafrost, freeze-thaw Histosol -ist Very high OM, wet Andisol -and Volcanic soils, Al-humus complexes (binds organics), mild temp, fairly moist Aridisol -id

Andisols

Andisols

Soil Orders Soil Order Ending Characteristics, etc. Entisol -ent Absence of distinct pedogenic horizons (genetic profile A/C) Inceptisol -ept Weak develop (genetic profile A/Bw/C) Gelisol -el Permafrost, freeze-thaw Histosol -ist Very high OM, wet (peats) Andisol -and Volcanic soils Aridisol -id No avail. H2O when plants growing – the largest group of soils on Earth!

Aridisols

Aridisols

Soil Orders Soil Order Ending Characteristics, location, etc. Vertisol Swelling clays, high fertility, dry-wet Mollisol -oll Ultisol -ult Alfisol -alf Spodosol -od Oxisol -ox

Vertisols

Vertisols

Soil Orders Soil Order Ending Characteristics, location, etc. Mollisol Vertisol -ert Swelling clays, high fertility Mollisol -oll Dark, thick epipedon, grasslands, some dry period, high fertility Ultisol -ult Alfisol -alf Spodosol -od Oxisol -ox

Mollisols Plate 8 Mollisols -- a Typic Hapludoll from central Iowa. Mollic epipedon to 1.8 ft (Scale in feet)

Soil Orders Soil Order Ending Characteristics, etc. Ultisol -ult Vertisol -ert Swelling clays, high fertility Mollisol -oll Dark, thick, grasslands Ultisol -ult Wet subtropical or tropical, highly acidic, high in clay, Fe and Al oxides Alfisol -alf Spodosol -od Oxisol -ox

Ultisols

Soil Orders Soil Order Ending Characteristics, etc. Alfisol -alf Vertisol -ert Swelling clays, high fertility Mollisol -oll Dark, thick, grasslands Ultisol -ult subtropical, acidic, high in clay, Fe, Al Alfisol -alf Moist, forested, mildly acidic, translocation of clays, moderate-high fertility Spodosol -od Oxisol -ox

Alifsols

Soil Orders Soil Order Ending Characteristics, etc. Spodosol -od Vertisol -ert Swelling clays, high fertility Mollisol -oll Dark, thick, grasslands Ultisol -ult Moist & warm, acidic, high in clay, oxides Alfisol -alf Moist, forested, clays Spodosol -od Translocation of humus and Al, Fe, cool, wet, sandy, coniferous forest Oxisol -ox

Spodosols

Spodosols

Soil Orders Soil Order Ending Characteristics, etc. Oxisol -ox Vertisol -ert Swelling clays, high fertility Mollisol -oll Dark, thick, grasslands Ultisol -ult Moist & warm, acidic . . . Alfisol -alf Moist, forested, clays Spodosol -od cool, wet, sandy, acidic . . . Oxisol -ox Extreme weathering, tropical forest, Fe, Al oxides, old, stable PM

Oxisols

If no subsurface horizons  The SUPER SIMPLIFIED guide to soil orders This is to complement those keys in ‘Study Guide–I’ If no subsurface horizons  If aridic moisture regime and NOT and Entisol  If mollic epipedon  If histic epipedon  If permafrost  Entisol Aridisol Mollisol Histosol Page 3-13 of notes more “technically correct” Gelisol Understand all the terms used in the key?  Review in text

The SUPER SIMPLIFIED guide (cont.) If on volcanic material  If TONS of clay, with shrink-swell features (“slickensides,” large cracks when dry)  If spodic horizon (Bh, Bs)  If oxic horizon (Bo)  Andisol Vertisols Spodosols Page 3-13 of notes more “technically correct” Oxisols

The SUPER SIMPLIFIED guide (cont.) If umbric epipedon (low BS), argillic horizon, subtropical location  If ochric epipedon (sometimes umbric), argillic horizon, often an albic horizon, and a cool, moist climate  If ochric epipedon and NOT an Entisol or Aridisol, often a cambic horizon  Ultisol Alfisol Page 3-13 of notes more “technically correct” Inceptisol