1. BRING SOME SOIL FROM YOUR HOME.
HOMEWORK:
BRING SOME SOIL FROM YOUR HOME.

2. Characteristics of Soil
CHAPTER 5.2 SOIL
Characteristics of Soil
Soil Composition
Soil Texture
Soil Structure

3. Regolith = small pieces of weathered rock
What is Soil?
Regolith = small pieces of weathered rock
MOON
EARTH
MARS

4. Soil Composition = what it’s made of

5. Different compositions of soils:
Soil Composition
Different compositions of soils:
HIGH % Organic Matter
LOW % Organic Matter

6. Different compositions of soils:
Soil Composition
Different compositions of soils:
HIGH % Air & Water
LOW % Air & Water

7. Soil Texture = proportions of different particle sizes
U.S. Dept of Agriculture – categories based on amounts of clay, silt and sand.
Soil-Texture Diagram (pg 134 Figure 11)
Loam has equal parts clay, silt and sand.
Loam is best for plant growth.

8. Soil-Texture Diagram % Silt % Clay % Sand 60% Clay; 10% Silt; 30% Sand10 20 30 40 50 60 70 80 90
100
Clay
Silty Clay
Silty Clay Loam
Silty Loam
Silt
Sandy Clay
Clay Loam
Sandy Clay Loam
Sandy Loam
Loamy Sand
Sand
Soil-Texture Diagram
% Clay
% Silt
% Sand
60% Clay; 10% Silt; 30% Sand

9. Soil Structure
To clump or not to clump.

10. Soil Formation Parent Material = source of minerals in soil.
Time = how long it took to form the soil.
Climate = did it form in dry or wet areas, under hot or cold temperatures, etc.
Organisms = what types of organisms are living or dead in the soil.
Slope = the angle of the land on which the soil forms.

11. Parent Material Who’s the mama? Pg. 135 Figure 12
Residual soil = forms on bedrock
formed on top of the parent material
Transported soil = forms unconsolidated soil
moved from parent material to another location.

12. Parent Material How did mama affect it?
Affects rate of weathering and rate of soil formation
Unconsolidated deposits are already weathered some, so they provide more surface area for chemical weathering.
Affects the soil’s fertility
More plant material can grow – more organic matter – better fertility.

13. How long did it take to form?
Time
How long did it take to form?
The longer it takes to form, the thicker it becomes.
As time passes, weathering can reduce the influence of the parent material.

14. How did and does “neighborhood” affect soils?
Climate
How did and does “neighborhood” affect soils?
Has greatest affect on soil formation.
Temperature changes affect rate, depth, and type of weathering.
Example: hot, wet climate produces a thick layer of chemically weathered soil.
Example: cold, dry climate produces a thin layer of chemical weathered soil.

15. How did and does “neighborhood” affect soils?
Climate
How did and does “neighborhood” affect soils?
Precipitation influences soil fertility.
Climate affects what types and how many animals and plants can live on the soil.
Climate can cause similar soils to be produced from different parent materials .

16. How does the “family” affect soil?
Organisms
How does the “family” affect soil?
Some soils named based on plants living in them.
Prairie soil, tundra soil, forest soil, etc.
Plants are main source of organic matter.
Protozoans decompose organic matter in soil.
Burrowing animals stir, pack and move soil.

17. Slope
Soils on the edge?
Slope varies greatly from location to location.
The steeper the slope, the faster the erosion and the less water can soak in.
Steep slopes have thin layers of soils or none at all.
Flat slopes have thick layers of soils.

18. Slope Soils on the edge? The direction a slope faces can affect soils.
South-facing slopes receive more sunlight so are warmer and dryer.
North-facing slopes receive less sunlight so are colder and wetter.
All of these factors work together to affect the formation of soils.

19. Soil Formation – Summary

20. SOIL PROFILES = shows soil layers and composition of a section of earth.
A Horizon
“topsoil”
loose, partly decayed organic matter
mineral matter mixed with organic matter
insects, fungi, worms, microorganisms

21. SOIL PROFILES = shows soil layers and composition of a section of earth.
B Horizon
“subsoil”
fine clay washed out of Horizon A
sometimes packed into “hardpan” soil
lower limit of plant roots and burrowing animals.

22. SOIL PROFILES = shows soil layers and composition of a section of earth.
C Horizon
partially weathered parent material
still resembles the parent material

23. SOIL PROFILES = shows soil layers and composition of a section of earth.
Rock
parent material
unweathered

24. SOIL TYPES
Three common types of soil:
PEDOCAL
PEDAL
FER
LATERITE

25. SOIL TYPES: Pedalfer Temperate areas receiving > 63 cm/yr
Rutherford County, NC
B Horizon has lots of iron oxide and aluminum clay.
Red or brown color

26. SOIL TYPES: Pedocal Areas with grasses and brush vegetation.
Western USA
B Horizon has lots of iron oxide and aluminum clay.
Red or brown color

27. SOIL TYPES: Laterite Hot, wet tropical areas. Deeper than other soils.
When dry, becomes very hard and almost waterproof.
Used in brick-making. Pg 139 Fig 15
Red or orange color

28. SOIL TYPES: Laterite (cont.)
Makes up much of the soil in rainforests.
Plants decompose so rapidly in the rainforest there is no organic matter in laterite.
Not fertile.

29. SOIL TYPES: Laterite (cont.)

30. SOIL EROSION How WATER erodes soil…
IMPACT erosion is a physical effect of water on soil.
When falling water hits soil it creates a tiny explosion that tosses soil into the air and displaces it.

31. SOIL EROSION How WATER erodes soil…
This is an erosion bed. It is used to test the affects of running water on different types of soil.
Here is the bed BEFORE the water is released.
FLOWING water picks up particles of soil and carries them with it.
This results in a deposition of soil from its original location to another location downstream.
Here is the bed AFTER the water is released.

32. SOIL EROSION Rates of erosion…
In the past soil erodes more slowly than it does today because more land was covered by plants.

33. SOIL EROSION Rates of erosion…
Human activities that remove natural vegetation have greatly accelerated erosion.

34. SOIL EROSION Rates of erosion…
Before humans, rivers carried 9 trillion kg of sediment to the oceans each year.

35. SOIL EROSION Rates of erosion…
Today rivers carry about 24 trillion kg of sediment to the oceans each year!

36. SOIL EROSION Rates of erosion…
Excessive erosion causes excessive sediment deposition in rivers.

37. SOIL EROSION Rates of erosion…
Wind can also carry displace large amounts of soil if the land becomes dry from a severe drought.
1930’s Dust Bowl

38. SOIL EROSION Controlling erosion… Terracing Windbreaks Landscaping
Crop Rotation
Erosion Walls and Fences