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
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Lecture 5a Soil Taxonomy Purpose of Soil Taxonomy: 1. Organize knowledge about soils 2. Understand relationships among different soils 3. Establish groups.
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Lecture 5aSoil 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- 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
1) Orders (12)2) Suborders (54)3) Great Groups (211)4) Subgroups (1,100+)5) Family (7,000+)6) Series (a lot!)
Fine-loamy mixed, superactive, mesic Aquic Argiudolls(This is the name of a specific soil in Soil Taxonomy)
This is the name of oneOf the 12 large categories
Mollisol - oll
Oder - root of order
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
Series = Le Sueur – this is where the soils of the week names are from – ie Lester, Clarion, Nashwauk
etc.
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.)
Natric - same as argillic but with > 15% exchangeable sodium (Na) - Btn
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 or Bhsm
OiEBhsBs
C
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
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