Chapter 2

advertisement
Chapter 2 Formation of Soils from Parent Materials
Sampling moon “soil.” (NASA, Apollo 14)
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.1
(a)
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
(b)
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.2
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.3
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Physical Weathering Processes
• Unloading
• Temperature
– Thermal Expansion
– Freeze-Thaw
– Frost Wedging
• Abrasion
– Water, Ice, Wind
• Biological Activity
– Burrows
– Root Wedging
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Biogeochemical Weathering Processes
• Hydration
– Intact water molecules combine with a mineral
5Fe2O3 + 9H2O
Fe10O15(9H2O)
• Hydrolysis
– Water Molecule splits into hydrogen and a hydroxyl and
the hydrogen replaces a cation from the mineral structure
KAlSi3O8 + H2O
HAlSi3O8 + K+ + OH-
• Dissolution
– Aided by small amounts of acid in the water
– Soluble ions are retained in the underground water supply
CaCO3 + 2[H+(H2)O]
Ca2+ + CO2 + 3H2O
OR
CaSO4(2H2O) + 2H2O
Ca2+ + SO42- + 4H2O
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Biogeochemical Weathering Processes
• Carbonation
– Weathering is accelerated by the presence of weak acids
CO2 + H2O
H2CO3 (Carbonic Acid)
Then
H2CO3 + CaCO3
Ca2+ + 2HCO3-
• Oxidation-Reduction
– Any chemical reaction in which a compound or radical loses
electrons
– Important in decomposing ferromagnesian minerals
4Fe + 3O2
2Fe2O3
Or
4Fe(2-)O + O2 + 2H2O
4Fe(3-)OOH (Goethite)
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.5
(a)
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
(b)
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.6
(a)
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
(b)
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Development of Clays
• The breakdown of parent rock results in the
development of clays
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Factors Influencing Soil Formation
CLORPT
• Climate
– Primarily precipitation and temperature
• Organisms
– Especially vegetation, microbes, and soil animals
• Relief
– Slope, aspect, and landscape position
• Parent Material
– Geological or organic precursors to the soil
• Time
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Effects of Parent Material
• The parent material is what the soil and the
nutrients ultimately come from
– Examples
•
•
•
•
•
•
•
Colluvium
Alluvium
Floodplain
Glacial
Marine Sediments
Loess
Organic Bogs
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.11
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.12
A productive soil in the Appalachian Mountains formed on colluvium
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.14
Alluvial fans merging into a Bajada in Alaska,
which will form well-drained soils
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.13
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.15
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Glacial Erosion
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Glacial Erosion
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.17
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.16
1. Till deposits of various kinds
2. Glacial-lacustrine deposits
3. The Loessial blanket
4. Area that escaped glaciation but has loess
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.18
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.19
Glacial
Till
Glacial
Outwash
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.20
Distribution of Dune Sands and Loess Deposits
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Homes carved from Loess deposits in China
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.22
Development of a peat bog resulting in Histosols
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Effects of Climate
• Effective Precipitation
– Depends on timing, topography, and soil type
• Temperature
– Effects the rate of weathering
• Climate also affects vegetation
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Box 2.1
a. Seasonal Distribution, b. Temperature and Evaporation, c. Topography, d Permeability
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.23
Temperature and Precipitation work together to affect depth of regolith weathered from bedrock
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.24
Climate and Vegetation are interconnected
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Effects of Organisms
• Flora
– Lichen, Moss, Trees
• Fauna
– Mites, Nematodes, Springtales, Earthworms
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.8
The effect of lichen etching bedrock
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.25
Difference in the soil profile under grassland versus forest vegetation
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Change in soil Ph because of forest type
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Semiarid rangeland vegetation will locally enhance fertility,
photos from Patagonia Argentina
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.28
Prairie dog burrows help to mix the soil (called crotovinas),
photo taken in Illinois
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Effects of Topography
• Slope and Aspect
– Determines amount of solar radiation absorbed
• Parent Material Interactions
– Affects the distribution of colluvium and alluvium
• Salt Buildup
– Arid areas slats are leached from relatively higher areas to lower
areas
• Interaction With Vegetation
– Moisture regime is affected by microtopographic changes which in
turn controls vegetation distributions
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.29
Topographic influence on soil depth
(a)
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
(b)
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.30
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Effects of Time
• All soil forming processes occur over a very long
period of time
• The time it takes to develop a soil is relative,
dependent upon
– Climate
– Vegetation
– Human Interaction
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.31
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
When Everything Else Is Held Equal
(Sequences)
• Catenas
– When soils are developed on the same parent material and the soils
only differ on the basis of drainage due to variations in relief
• Chronosequence
– A sequence of related soils that differ in certain properties
primarily as a result of time as a soil-forming process
• Lithosequence
– A group of related soils that differ as a result of parent material
• Climosequence
– A sequence of soils that differ as a result of changes in climatic
regimes (temperature and precipitation)
• Biosequence
– A group of related soils that differ primarily due to variation in
kinds and numbers of plants and soil organisms
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Four Basic Processes of Soil Formation
• Transformation
– When soil constituents are chemically or physically modified or
destroyed and others are synthesized from precursor materials
• Translocation
– The movement of organic and inorganic materials horizontally or
vertically across a pedon
• Additions
– Inputs of materials from outside sources (i.e. plant litter)
• Losses
– Materials that are removed from the soil profile by leaching or
erosion
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Figure 2.32
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
THE NATURE AND PROPERTIES OF SOILS, 13/e
Nyle C. Brady and Ray R. Weil
©2002 Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
Download
Related flashcards

Oxygen heterocycles

49 cards

Acetates

46 cards

Tetrapyrroles

47 cards

Organic peroxides

30 cards

Keto acids

33 cards

Create Flashcards