1. GES 175: Science of Soils
Laboratory
Week 1

2. Soil Development Soil vs Regolith Soil Regolith = weathered portion
Bedrock
Soil
= weathered portion
of regolith
Regolith
= unconsolidated material above bedrock
bedrock

3. Soil Profile contains characteristic layers called horizons A E soil B
development
Bedrock C
Bedrock

4. Material Transolcation/Development

5. Soil Profile
Argixerol
Soil Horizons

6. Soil Profile
Soil Horizons A Bw E BE
Btb
Argixerol C

7. Master Horizons O horizon-Organic A horizon-Mineral & Organic
E horizon-Eluviation (Loss)
B horizon-Illuviation (Gain)
C horizon- little Alteration from Parent Material
R horizon- Bedrock

8. Master Horizons
O horizons: Layers dominated by organic material. Some are saturated with water for long periods or were once saturated but are now artificially drained; others have never been saturated.

9. Master Horizons
A horizons: Mineral horizons that formed at the surface or below an O horizon, that exhibit obliteration of all or much of the original rock structure
-an accumulation of humified organic matter
intimately mixed with the mineral fraction and not
dominated by properties characteristic of E or B horizons
-properties resulting from cultivation, pasturing,
or similar kinds of disturbance.

10. Master Horizons
E horizons: Mineral horizons in which the main feature is loss (eluviation) of silicate clay, organic matter, iron, aluminum, or some combination of these, leaving a concentration of sand and silt particles.

11. Master Horizons
B horizons: Horizons that formed below an A, E, or O horizon and are dominated by obliteration of all or much of the original rock structure
(1) (illuvial) concentration of silicate clay, iron, aluminum, humus, carbonates, gypsum, or silica
(2)coatings of sesquioxides that make the horizon lower in value, higher in chroma, or redder in hue than overlying and underlying horizons
(3)alteration that forms granular, blocky, or prismatic structure

12. R horizons or layers: Hard Bedrock
Master Horizons
C horizons or layers: Horizons or layers, excluding hard bedrock, that are little affected by pedogenic processes and lack properties of O, A, E, or B horizons. Most are mineral layers.
R horizons or layers: Hard Bedrock

13. 12 Soil Orders I AM A SUAVE HOG or I GAVE US OMAHA
Compliments of Prof. M.J. LaForce

14. I AM A SUAVE HOG Inceptisol- Soils with weakly developed subsurface
horizons
Alfisol- Soils with a subsurface zone of silicate clay accumulation and >35% base saturation
Mollisol- Grassland soils with high base status
Andisol- Soils formed in volcanic ash
Spodosol-Acid soils with a subsurface accumulation of metal-humus complexes
Ultisol- Subsurface zone of silicate clay accumulation and
<35% base saturation

15. I AM A SUAVE HOG
Aridosol- Soils in Arid environments with moderate to strong development
Vertisol- Clayey soils with high shrink/swell capacity
Entisol- Soils with little or no morphological development
Histosol- Organic soils
Oxisol- Intensely weathered soils of tropical and subtropical environments
Gelisol- Soils with permafrost within 2 m of the surface

16. Twelve Soil Orders Entisol (recent) Inceptisol (L.-inceptum, begging)
Mollisol (L.-mollis, soft)
Alfisol (pedalfter)
Ultisol (L.-ultimus, last)
Oxisol (Fr.-oxide)
Increasing Soil Depth
Maturation (loss of Si)

17. Twelve Soil Orders Aridisol (L.-aridus, dry)
Spodosol (Gr.-spodos, wood ashes
Gelisol (Gr.-gelid, very cold)
Vertisol (L.-verto, turn)
Andisol (L.-aridus, dry)
Histosol (Gr.-histos, tissue)
Climate Specific
Material Specific

18. Ideal Weathering Series
Rock
Ideal Weathering Series
Entisol
Inceptisol
Aridisol (dry climate)
Mollisol
Vertisol (clay mineralogy)
Alfisol
Spodosol
(cool and wet)
Ultisol
Oxisol

19. Entisol -(ent) Shallow to bedrock. Limited use and management.
The most common uses are rangeland

20. Inceptisol- (ept) Steep slopes and cool climate slow soil development.
Inceptisols are widely distributed and occur under a wide range of environmental settings.

21. Mollisol
-(oll)
Soil formation under native grassland vegetation

22. Alfisol
(-alf)
Alfisols are mostly found in temperate humid and subhumid regions of the world.
Developmentally just past Mollisols

23. Histosol
-(ist)
Organic matter is highly decomposed and has few remaining plant fibers.

24. Vertisol
-(ert)
Abundant, ‘active’ clay particles are dominant

25. Aridosol -(id) Form in dry climates
White crust at the soil surface is a mixture of various soluble salts (definitely not snow!).

26. Gelisol -(el) Permafrost persists below 38 cm year-around.
The lack of significant microbial activity in these soils leads to an accumulation of organic matter.

27. Gelisols are in very cold climates and typically contain permafrost

28. Web Sites of Interest NRCS
Universities
Keys to Soil Taxonomy