Soil Taxonomy- Properties of Soil Plant & Soil Science

Property #1: Soil has Horizons (layers)

Property #2: Soil has Color…

Property #3: pH Levels

Soil Property #4 - Organic Content Desert soils have low organic content. Grasslands have high organic content. The exact type of vegetation is also important because it also affects pH. Pine needles add acid to the soil. Grasses conserve calcium and magnesium (bases). Most crops like a neutral pH.

Order

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

Soil Taxonomy Fine-loamy mixed, superactive, mesic Aquic Argiudolls (This is the name of a specific soil in Soil Taxonomy) Orders (12) Suborders (54) Great Groups (211) Subgroups (1,100+) Family (7,000+) Series (a lot!) This is the name of one Of the 12 large categories Mollisol - oll Oder - root of order

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

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

Great Groups (not required to know) Fine-loamy mixed, superactive, mesic Aquic Argiudolls Sub Order Order Great Group Based on differences between soil horizons Argi = Clay accumulation

Sub Groups (not required to know) Fine-loamy mixed, superactive, mesic Aquic Argiudolls Sub Order Sub Group Describes a profile characteristic, wetness, sand, etc. Order Great Group Aquic = wet soil

Family (not required to know) Fine-loamy, mixed, superactive, mesic Aquic Argiudolls Sub Order Sub Group Family Texture, clay minerals, CEC, temp, Order Great Group Based on soil properties that affect management and root penetration, such as texture, temperature, and depth

Series (not required to know) Fine-loamy mixed, superactive, mesic Aquic Argiudolls Sub Order Sub Group Family Order Great Group Named from the town or landscape feature near where the soil was first recognized (Eleva= Eleva, WI or Gale for Galesville, WI .)

Soil Orders – Upper Midwest

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

The 12 Soil Orders

Orders with unique parent materials:

Andisols (and) Volcanic ash soils.

Histosols (ist) Organic soils.

Vertisols (ert) High shrink/swell clay soils.

Orders formed in unique environments.

Aridisols (id) Arid climates. CaCO3 accumulation in subsoil.

Gelisols (el) Colder climates. Permafrost layer within 2 m of surface.

Oxisols (ox) Tropics and subtropics. Intensely weathered.

Orders by age.

Entisols (ent) ‘Baby’ soil. Little to no morphological development.

Inceptisols (ept) ‘Toddler’ soils. Weakly developed sub-surface horizons.

Ultisols (ult) Older soils. “Ultimately weathered”. Strongly leached. Sub-surface clay accumulation. < 35% base sat. in sub-soil.

Orders developed under unique vegetative ecosystems.

Alfisols (alf) Forest soils. Usually an A-E-B type horizon development. The A horizon is usually less than 25 cm.

Mollisols (oll) Grasslands soil. Thick, dark A horizon. High % base saturation.

Spodosols (od) Acid forest soils. Usually sandy. Thick, bright white E horizon. Sub-surface layer of accumulated metal-humus complex (Bhs and Bs horizons).

Summary: 3 orders with unique parent materials (Andisols, Histisols, Vertisols). 3 orders with unique environments (Aridisols, Gelisols, Oxisols). 3 orders by age of development (Entisols, Inceptisols, Ultisols). 3 orders by unique vegetative influence (Alfisols, Mollisols, Spodosols).

Resources http://soils.usda.gov/technical/soil_orders/ http://www.soils4teachers.org/lessons-and-activities http://www.cals.uidaho.edu/soilorders/orders.htm