Podcast
Questions and Answers
What are the five factors of soil formation?
What are the five factors of soil formation?
Parent materials, Climate, Biota, Topography, Time.
Do the five factors of soil formation act independently?
Do the five factors of soil formation act independently?
False (B)
What are the two types of weathering?
What are the two types of weathering?
Physical (mechanical) and chemical.
What is physical weathering?
What is physical weathering?
What is chemical weathering?
What is chemical weathering?
What is the chief chemical agent?
What is the chief chemical agent?
Why is climate considered to be the most influential factor acting on parent material?
Why is climate considered to be the most influential factor acting on parent material?
The principle climatic variables influencing soil formation are ________ and _______.
The principle climatic variables influencing soil formation are ________ and _______.
What type of biome has the most amount of litter accumulation?
What type of biome has the most amount of litter accumulation?
What biome has the least amount of litter accumulation?
What biome has the least amount of litter accumulation?
What are the methods of mechanical weathering?
What are the methods of mechanical weathering?
What is frost action?
What is frost action?
What does frost action require?
What does frost action require?
How do plants cause physical weathering of rocks?
How do plants cause physical weathering of rocks?
What is exfoliation?
What is exfoliation?
Many reactions proceed more quickly as temperature ________.
Many reactions proceed more quickly as temperature ________.
With biological processes, for every ______ rise in temperature, the rates of biochemical reactions double.
With biological processes, for every ______ rise in temperature, the rates of biochemical reactions double.
How do temperature and moisture influence the organic matter content of soil?
How do temperature and moisture influence the organic matter content of soil?
If warm temperatures and abundant water are present in the profile at the same time, the processes of weathering, leaching and plant growth will be ________.
If warm temperatures and abundant water are present in the profile at the same time, the processes of weathering, leaching and plant growth will be ________.
Increasing effective annual precipitation generally leads to:
Increasing effective annual precipitation generally leads to:
High temperatures result in faster __________ rates.
High temperatures result in faster __________ rates.
How do waves physically weather rock material?
How do waves physically weather rock material?
Smaller particles have a greater surface area, resulting in more rapid _________.
Smaller particles have a greater surface area, resulting in more rapid _________.
How do plants cause chemical weathering?
How do plants cause chemical weathering?
_______ is essential for all the major chemical weathering reactions.
_______ is essential for all the major chemical weathering reactions.
To be effective in soil formation, water must ________ into the regolith.
To be effective in soil formation, water must ________ into the regolith.
What determines how effectively precipitation can influence soil formation?
What determines how effectively precipitation can influence soil formation?
The greater the depth of water penetration, the greater the depth of _______.
The greater the depth of water penetration, the greater the depth of _______.
What does percolating water stimulate?
What does percolating water stimulate?
How does the deficiency of water affect soils in dry regions?
How does the deficiency of water affect soils in dry regions?
Increasing water ________ chemical weathering rates.
Increasing water ________ chemical weathering rates.
What is effective precipitation?
What is effective precipitation?
What does increasing effective precipitation do?
What does increasing effective precipitation do?
How does oxidation and reduction relate to the aeration of soils?
How does oxidation and reduction relate to the aeration of soils?
How does water affect the decomposition rate of organic matter in soil?
How does water affect the decomposition rate of organic matter in soil?
Organic decomposition is faster when the conditions are ________.
Organic decomposition is faster when the conditions are ________.
What are characteristics of desert soils?
What are characteristics of desert soils?
What are characteristics of the humid tropics?
What are characteristics of the humid tropics?
A increase in rainfall results in increased ________.
A increase in rainfall results in increased ________.
A decrease in temperature results in increased ________.
A decrease in temperature results in increased ________.
What is the cycle that nutrients take in the ecosystem?
What is the cycle that nutrients take in the ecosystem?
What are characteristics of a grassland?
What are characteristics of a grassland?
In the grassland, much of the organic matter added to the soil is from ______.
In the grassland, much of the organic matter added to the soil is from ______.
What is the source of most organic matter in a forest?
What is the source of most organic matter in a forest?
What other characteristic about grasslands leads to organic matter formation?
What other characteristic about grasslands leads to organic matter formation?
The soils under grasslands generally develop a thicker _______ horizon.
The soils under grasslands generally develop a thicker _______ horizon.
Where do forests store most of their organic matter?
Where do forests store most of their organic matter?
The microbial community in a typical grassland is dominated by _______.
The microbial community in a typical grassland is dominated by _______.
Forest soil is dominated by ______.
Forest soil is dominated by ______.
What horizon is commonly found in forested areas that is typically not found in grasslands?
What horizon is commonly found in forested areas that is typically not found in grasslands?
How does the leached E horizon form?
How does the leached E horizon form?
Tree leaves, especially conifers, have ________ acids that promote weathering.
Tree leaves, especially conifers, have ________ acids that promote weathering.
What are characteristics of a deciduous forest?
What are characteristics of a deciduous forest?
What are characteristics of an evergreen forest?
What are characteristics of an evergreen forest?
Litter falling from coniferous trees will recycle only ______ quantities of calcium, magnesium, and potassium compared to those recycled by litter from some deciduous trees.
Litter falling from coniferous trees will recycle only ______ quantities of calcium, magnesium, and potassium compared to those recycled by litter from some deciduous trees.
What are the anthropogenic effects (human effects) on soil?
What are the anthropogenic effects (human effects) on soil?
Earthworms, termites, and rodents act as _______, moving weathered materials and organic matter up and down the soil profile.
Earthworms, termites, and rodents act as _______, moving weathered materials and organic matter up and down the soil profile.
Large animals _______ the soil, which reduces air space.
Large animals _______ the soil, which reduces air space.
Vegetation is the ______ for most microorganisms thus influences soil microbial populations.
Vegetation is the ______ for most microorganisms thus influences soil microbial populations.
Natural vegetation helps to _______ the soil and protect it from the ravages of soil erosion.
Natural vegetation helps to _______ the soil and protect it from the ravages of soil erosion.
What does the topography of a landscape influence?
What does the topography of a landscape influence?
Gravity results in a general trend for water to flow from ________ to ________.
Gravity results in a general trend for water to flow from ________ to ________.
Which is deeper, soils on hillsides or soils on flat terrains?
Which is deeper, soils on hillsides or soils on flat terrains?
Level areas on summits have high _________ generally.
Level areas on summits have high _________ generally.
Level areas on foot-slopes have higher ________ and higher _______ and lower _________.
Level areas on foot-slopes have higher ________ and higher _______ and lower _________.
Systems that contain a lot of ridges tend to absorb ______ than systems that are flat.
Systems that contain a lot of ridges tend to absorb ______ than systems that are flat.
A convoluted surface dilutes solar energy over _______ surface area than does a smooth surface.
A convoluted surface dilutes solar energy over _______ surface area than does a smooth surface.
In the northern hemisphere, a north-facing slope will be ______ than a south-facing slope.
In the northern hemisphere, a north-facing slope will be ______ than a south-facing slope.
Depressed areas can have accumulation of water leading to the formation of ______ and in turn ______.
Depressed areas can have accumulation of water leading to the formation of ______ and in turn ______.
The longer a soil parent material stays in place for the soil-forming processes to act upon it, the _____ the horizon development and the _______ it forms.
The longer a soil parent material stays in place for the soil-forming processes to act upon it, the _____ the horizon development and the _______ it forms.
Clays are _______ minerals.
Clays are _______ minerals.
What are characteristics of clays?
What are characteristics of clays?
What are characteristics of organic matter?
What are characteristics of organic matter?
Residual parent materials have generally been subjected to soil-forming processes longer than transported parent materials.
Residual parent materials have generally been subjected to soil-forming processes longer than transported parent materials.
Recently deposited alluvium alongside a stream has had too little time for __________ to take place.
Recently deposited alluvium alongside a stream has had too little time for __________ to take place.
Soils developed from glacial parent materials and coastal plain areas are generally less weathered than those developed from residual materials.
Soils developed from glacial parent materials and coastal plain areas are generally less weathered than those developed from residual materials.
How is soil age considered?
How is soil age considered?
Young soils have ________ soil development and _______ horizons.
Young soils have ________ soil development and _______ horizons.
Old soils have well ________ developed horizons.
Old soils have well ________ developed horizons.
Where are the oldest soils in the United States?
Where are the oldest soils in the United States?
Where are the youngest soils in the United States?
Where are the youngest soils in the United States?
Where are the oldest soils in the world?
Where are the oldest soils in the world?
It takes ________ time for surface horizons to develop than subsoil horizons.
It takes ________ time for surface horizons to develop than subsoil horizons.
What is steady state?
What is steady state?
What are soil-forming factors that hasten the rate of soil formation?
What are soil-forming factors that hasten the rate of soil formation?
What conditions are prone to retard soil development?
What conditions are prone to retard soil development?
As we go through time, what happens with soil development?
As we go through time, what happens with soil development?
Flashcards
Physical Weathering
Physical Weathering
The breaking down of materials without changing their chemical composition.
Chemical Weathering
Chemical Weathering
The alteration of materials through chemical reactions.
Water
Water
The primary chemical weathering agent, crucial for soil formation.
Climate
Climate
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Temperature
Temperature
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Precipitation
Precipitation
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Boreal Forest
Boreal Forest
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Tropical Rainforest
Tropical Rainforest
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Thermal Expansion and Contraction
Thermal Expansion and Contraction
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Frost Action
Frost Action
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Plant Roots
Plant Roots
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Plant Processes
Plant Processes
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Leaching
Leaching
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Organic Matter Content
Organic Matter Content
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Decomposition Rates
Decomposition Rates
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Desert Soil
Desert Soil
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Humid Tropical Soil
Humid Tropical Soil
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Nutrient Cycling
Nutrient Cycling
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Grasslands
Grasslands
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Bacteria
Bacteria
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Fungi
Fungi
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A Horizon
A Horizon
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E Horizon
E Horizon
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Older Soils
Older Soils
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Younger Soils
Younger Soils
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Sierra Nevada Mountains, California
Sierra Nevada Mountains, California
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Arizona and New Mexico Deserts
Arizona and New Mexico Deserts
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Australia
Australia
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Warm, Humid Climates and Well-Drained Landscapes
Warm, Humid Climates and Well-Drained Landscapes
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Cold, Dry Climates and Impermeable Parent Materials
Cold, Dry Climates and Impermeable Parent Materials
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Soil Development Over Time
Soil Development Over Time
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Study Notes
Five Factors of Soil Formation
- Parent materials, climate, biota, topography, and time influence soil formation collectively, not independently.
- Physical and chemical weathering are the two main types impacting soil formation.
- Physical weathering breaks down materials without changing their chemical composition, while chemical weathering alters materials through chemical reactions.
Key Weathering Agents
- Water is the primary chemical agent in weathering processes.
- Climate is crucial as it dictates the nature and intensity of weathering in specific geographic areas.
Climatic Influence
- Temperature and effective precipitation are the main climatic variables influencing soil formation through their effects on weathering, leaching, and biological processes.
- A boreal forest biome has the highest litter accumulation due to slow organic matter decay in cold climates.
- Tropical rain forests experience rapid organic matter decay, leading to the lowest litter accumulation.
Mechanical Weathering Processes
- Mechanical weathering includes expansion and contraction due to temperature changes and frost action, which requires moisture, access for water, and fluctuating temperatures.
- Plant roots can physically weather rocks by cracking them, increasing soil formation.
Chemical Weathering Processes
- Chemical weathering includes effects from plant processes that release organic acids and CO2, aiding in rock breakdown.
- Effective precipitation is pivotal for chemical weathering, enhancing the movement of materials in soil profiles.
Soil Characteristics and Influences
- Temperature and moisture together influence organic matter content and decomposition rates, where warm and wet conditions maximize weathering and growth.
- Desert soils are shallow and primarily feature mechanical weathering, while humid tropical soils are deeper with extensive chemical weathering.
Nutrient Cycling in Ecosystems
- Nutrients cycle from soil to plants, returning to the soil surface via plant residues and decomposition.
- Grasslands exhibit rapid nutrient cycling, contributing significant organic matter from deep root systems.
Microbial Populations in Soils
- Grasslands are predominantly populated by bacteria, while forest soils have a higher prevalence of fungi.
Soil Horizon Development
- Grassland soils often develop thicker A horizons due to organic matter contributions, while forest soils have an E horizon resulting from leaching by organic acids.
- Older soils feature well-developed horizons, while younger soils show minimal development with few distinct layers.
Soil Age and Geographic Variation
- The oldest soils in the U.S. are found in California's Sierra Nevada, while the youngest are in Arizona and New Mexico deserts.
- Globally, Australia's stable landscapes feature some of the oldest soils.
Conditions Affecting Soil Development
- Factors that enhance soil formation include warm, humid climates and well-drained landscapes, while cold, dry conditions and impermeable parent materials hinder development.
- Over time, soils see an increase in thickness, iron accumulation, clay content, and acidity, while nutrient leaching may reduce fertility.
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Explore the five essential factors of soil formation with these flashcards. Learn about the interplay of parent materials, climate, biota, topography, and time in shaping soil. Ideal for students studying ecology and environmental science.