1. Characteristics that differentiate soil horizons
Color
Texture
Density
Structure
Consistence
Organic Matter content
Acidity
Mineral Accumulations
Biological activity

2. Original Russian Concept

3. o
Zone of eluviation
Zone of illuviation

4. Only 1 letter “l” E

5. Prairie dominated the flat expanses Forest dominated the hilly land
thin A horizon
weak E horizon
strong B horizon
Illinois once was covered by a complex mix of prairie and forest
Prairie dominated the flat expanses
Forest dominated the hilly land

6. Young Soil in NC Old Soil in NC
Poorly Defined Horizons Low Degree of Weathering Slightly Leached Thin Solum
Well Defined Horizons High Degree of Weathering Highly Leached Thick Solum

7. Water driven translocations
Illuviation
Eluviation
Illuviation
Illuviation

8. Adapted from Stewart (1990)
Precipitation
plus solutes,
aerosols and
particulates
Additions
Additions
Sediment
Loss of gases
N2, N2O, CO2
Losses
Soil forming processes
Sediment
Losses
Capillary
rise of
dissolved
ions
E(i)lluviation of
clay
CaCO3
dissolved ions
dissolved OM
Organic residues  humus
Primary  Secondary
minerals minerals
TRANSLOCATIONS
TRANSFORMATIONS
TRANSLOCATIONS
Capillary
rise of
salts
Additions
Leaching of
dissolved
ions & OM
Losses
Adapted from Stewart (1990)

9. Conceptual chronosequence

10. Master horizons are designated using capital letters
Horizon nomenclature
Master horizons are designated using capital letters
(O, A, E, B, C).
Lowercase suffixes (aka subscripts) are used to denote specific horizon characteristics or features
(e.g., Oi, Oe, Oa, Bt, Btg, Bx)
Numbers following master horizon letters indicate unspecified changes in properties (e.g., A2, A3)
Numbers preceding master horizon letters indicate changes in parent material (e.g., 2A, 2B)
Combinations of master horizon letters indicate transition zones (e.g., AE, BC)

11. Sometimes a soil’s horizons are very difficult to interpret.
Consider the profile to the left:
How many different parent materials are represented ?
Where would one find such a soil ?

12. The best way to look at soil profiles

13. Soil profiles can
be investigated
using a soil auger

14. What is this guy doing ??

15. Making a soil monolith

16. Hue
Munsell color
book
Value
Chroma
Low #s

17. “Texture by feel”

19. Soil Structure Platy Blocky Granular crumb structure Columnar
Prismatic

20. Soil Consistence
Loose
Friable
Firm
Very Firm