1. SOIL - Fundamental Concepts ABIOTIC
Prepared by
Earl D. Lockridge
National Soil Survey Center
Lincoln, NE
Amended by: Mr. R

2. SOIL (Know this one)
A mixture of mineral matter, organic matter, water, and air that originated from weathered bedrock and has become differentiated with depth into horizons
Composite definition added Geomorphology book

3. SOIL
Mature soil- clearly defined horizons produced by the weathering process. Each layer encroaches on the layer below it
Paleosols - ancient soils removed from the zone of soil formation, usually by burial from younger sediments.

4. Major Components
Mineral matter
Organic matter
Air
Water

5. SOIL
Component definition: Mixture of mineral matter, organic matter, water, and air.
Example:
Air 25%
Mineral Matter 45%
Water 25%
Organic Matter 5%

6. CLIMATE and TIME –are the most important factors in soil formation
bedrock- The igneous, metamorphic, and sedimentary components of the Lithosphere that may exist as mountains, cliffs, or low lying plains

7. Types of Bed Rock
Igneous- rock from volcanic sources or locations…can be very old
Examples- Granite & Quartz

8. Types of Bed Rock
Sedimentary- rock formed by long term deposition by wind and water. Frequently found in layers.
Examples- Sandstone & Shale

9. Types of Bed Rock
Metamorphic- rock which has been altered by high heat or pressure
Examples- slate (altered shale), gneiss (altered granite), diamond (carbon, coal)

10. parent rock- an area of bed rock that is the source of an area of soil

11. How do we get soils?

12. Over time the weathered material from the bed rock is covered by both living and dead organic material and a soil horizon develops in a dynamic way.
These layer become characteristically differentiated over time due to climatic factors in their environment

13. Weathering
Disintegration and decomposition of rocks by surface processes.
Geomorphology book

14. Weathering
Mechanical- the physical process of breaking apart rocks (frost/salt wedging, root growth)
Chemical- breakdown through chemical alteration (oxidation, hydrolysis, acid inorganic or organic derived from Lichen, fungi, bacteria, mosses and all vascular plant roots)
piru.alexandria.ucsb.edu/ ~tierney/TRS/lab6.htm –part of chemical definitdefinition taken form here

15. Factors that Affect Soil Structure
Kind of clay
Amount of organic matter
Freezing and thawing
Wetting and drying
Action of burrowing organisms
Growth of root systems of plants

16. Important Note
All of these have a loosening effect on the soil, but they have no effect on aggregate stability

17. Soil Forming Processes
Translocations
Transformations
Additions
Losses

19. Only one millimeter of topsoil is created on 2
Only one millimeter of topsoil is created on 2.5 acres every year (The Way the World Works, 1996 )

20. Differentiated layer of developed soils are known as HORIZONS

22. The Horizons
O- organic layer of decomposing plant material little mineral content
A- Organic acid design decomposing the parent material giving it a dark color. This is the zone of leaching. Dissolved chemical carried down from the surface. Accessible by plant roots. Most soil organisms found here O A

23. The Horizons
B- Zone of accumulation. More weathering then C. Parent material is hard to identify. Can be full of clay (more so then the above layers) and impermeable (red brown color common because of oxidation). Nutrients collect in this region-mineral leach up form the parent rock below B C
web.unbc.ca/~quarles/ nres/soc/ggroup/hp.html

24. The Horizons
C- Slightly weathered parent material (bed rock). Has not undergone leaching and accumulation to the same extent of above layers less oxidation then the B layer
D or R- Bed Rock
Bed Rock
(Exposed)

25. O A B C
nesoil.com/images/ massasoit.htm

26. Hint!!
Not all layers of soil may be present, but if they are they will always be in the following order O-A-(E)-B-C-R (or D)

27. Three Fractions of Mineral Matter
Sand 2-.5mm (diameter)
Silt mm
Clay smaller than .002mm

29. USDA Textural Triangle

30. Examples of Soil Structure

31. Soil Color Indicator of different soil types
Indicator of certain physical and chemical characteristics
Due to humus content and chemical nature of the iron compounds present in the soil

32. loams – most fertile soil (silt, sand and clay in equal parts with partials of intermediate size)

34. Why is loamy soil best?

35. Porosity Porosity- the measure of how much water a rock can hold
finer (silt, clay) the grain greater overall surface area so more porosity, more poorly connected however

36. Permeability permeability- how easily the water can be transmitted
permeability- how easily the water can be transmitted
larger pores allow water to pass through easily (sand size and larger)

38. There are 20,000 different types of soil in the United States
There are 20,000 different types of soil in the United States! (The Way the World Works, 1996 )

39. Local Soil Types

42. Pedogenic Pedogenic means pertaining to processes that add, transfer, transform, or remove soil constituents.

43. Physical Properties of Soil
Soil texture
Soil structure
Soil color
Bulk density

44. Aspects of Soil Structure
The arrangement into aggregates of desirable shape and size
The stability of the aggregate
The configuration of the pores

45. Factors that Affect Aggregate Stability
Kind of clay
Chemical elements associated with the clay
Nature of the products of decomposition or organic matter
Nature of the microbial population

46. Factors that Affect Soil Structure
Kind of clay
Amount of organic matter
Freezing and thawing
Wetting and drying
Action of burrowing organisms
Growth of root systems of plants

47. Important Note
All of these have a loosening effect on the soil, but they have no effect on aggregate stability

48. Major Forms of Iron and Effect on Soil Color
Form Chemical Formula Color
Ferrous oxide FeO Gray
Ferric oxide
(Hematite) Fe2O3 Red
Hydrated ferric oxide (Limonite) 2Fe2O3 3H2O Yellow

49. Bulk Density
Determined by dividing the weight of oven-dry soil in grams by its volume in cubic centimeters
The variation in bulk density is due largely to the difference in total pore space

50. Effects of Bulk Density
Engineering properties
Water movement
Rooting depth of plants

51. Abiotic soil lab interpretation questions:
1. What soil layers were present at HWWP?
2. Which layer was thickest, which was thinnest?
3. How does the climate present in this area lead to the development of this type of soil?
4. How do you think this type of soil affect the life forms present in the HWWP (plants, animals, bacteria, and fungi)?