1. Lecture 3a Naming Soil Horizons
Soil horizons (layers in the soil) are named so differences between soils can be identified.
Naming soil horizons takes practice

2. When soil scientists are describing a soil they will discuss a lot about what they are seeing and how it should be named.
And what they are not seeing and what it should not be called ?

3. Soil Judging
Students wanting more practice at naming soil horizons should take Soil 4511 and try out for the Soil Judging Team Students that participate in the “Soil Judging” contest get more practice with different soils from the region. (MN, SD, ND,MO,IA,KS,NE.
The contest this fall is in Minnesota near Cloquet.
Contest in Kansas 2006
2007 UM Soils Team in the Team Pit No. 1 in southwest Iowa: Left to right Meryl Larson, Erin Andrews, Nick Reep, and Nick Saumweber

4. Oi - undecomposed (fibris) Oe - moderate decomp. (hemis)
Organic Horizons
O - horizon - organic material (no mineral materials) ) forest litter ) organic soil or peat soils, or muck
Oi - undecomposed (fibris)
Oe - moderate decomp. (hemis)
Oa - decomposed (sapric)

5. Organic Soil Profile
This trenching
machine is digging
through the Oe
horizon of an
organic soil.
Trenches needed to
remove water so the
peat will dry before
harvest.

6. Organic Soil Horizons in a forest litterOe

7. Processes of Mineral Soil Horizon Formation
A. Additions - H2O, organic matter,air, soil particles, salt
B. Losses - H2O, organic matter, CO2 , nutrients by plant removal
C. Transformations - Changes to soil structure, development of clay minerals, weathering of minerals to elements, chemical Rx
D. Translocations - movement from one horizon to another of O.M. Clay, Water, Iron, & Nutrients in colloidal size, (very small particles) clay films on peds are evidence of this translocation = clay (film) coating

8. Mineral Soil Horizons
A horizon - surface horizons that accumulate O.M.
Ap = plowed soil Ap EB Bt Ap BC C

9. E Horizons
E - (formerly A2) - Translocation out - Zone of Eluviations - Leaching out
lighter in color than horizons above or below A E
E/B Bt BC C

10. B Horizons- two kinds:
a) Translocation in below an A, E, or O with an accumulation of clay, iron, humus (O.M. decomposed.) or carbonates (CaCO3) zones of illuviation
b) or alteration of the original parent material, development of color or structure - Bw Bt

11. C Horizons
C - little affected by pedogenic processes and lack properties of O-A-B-E- or is the Parent Material
Solum =
A + B
C horizon

12. Rock Horizons
R = hard rock
Cr = Soft Rock

13. Subscripts - all B horizons have a subscript, most transition horizons do not.
* a - sapric - organic soils - well decomposed
* b - buried soil horizon
d - dense - geogenic soil material (compacted by glacier)
* e - hemic - mod. decomp. - organic soil
f - frozen soil - permanently frozen, permafrost
* g - gleyed soil - gray color due to low O2 - reduction of Fe
* h - accumulation of humus - O.M. other than in the A or O horizons
* i - fibric - organic - non-decomposed
* k - accumulation of calcium carbonate (CaCO3)
* m - cementation - hard - indurated

14. Subscripts cont. n - sodium accumulation
* p - plowing - only used with A
q - silica accumulation - very weathered or old soil
* r - soft rock - used with C or Cr
* s - sesquioxides (1.502) (Fe2O3) accumulation of Fe and Al - red color
*ss – slickensides present –shiny surface on ped face caused from soil rubbing against soil
* t - clay accumulation - clay films
* w - color or structure development (Bw)
x - Fragipan - hard, dense layer that developed with time
y - gypsum accumulation (CaSO4)
z - salts more soluble than gypsum (KCL - NaCl - NaSO4)

15. Transition Horizons AB - Like A - some of B BA - Like B - some of A
AE AC BC
E/B - Both E and B particles are present -
“B & E” used for soils with Lamellae thin bands of accumulating clay and iron in sandy soils

16. Lithologic DiscontinuityA1 A2 2B
Designated by number in front of horizon.
(More than one parent material)
2 parent
materials

18. AB Bk C DYAD – Name 4 horizons Using one transition horizon --- A
Practice at naming horizons – Soil from Badlands of North Dakota---Texture of horizons 1,2,3,4 = loam---Note Carbonates in horizon 3
DYAD – Name 4 horizons Using one transition horizon
--- A AB Bk C

19. Sandy soil from Northeast Minnesota Texture of Horizon 1,2,3,4 = Sand

20. Goodhue County Soil, Southwest of Redwing Mn
Goodhue County Soil, Southwest of Redwing Mn. Texture of horizon 1 & 2 = Silt Loam, Hrz 5 = Silty Clay Hrz. 4 = Cobbly loam, Hrz. 5 = Loam A E Bt
2BC 2C

21. This is not soil. It is a "rock outcrop" The End
This is not soil. It is "dune land"