PLS 366 EXAM 1 QUESTIONS & ANSWERS
What is soil? - Answers -A natural body consisting of layers of mineral and organic
materials of variable thickness
What are the six key functions of soils in ecosystems - Answers -Serves as a natural
medium
Provides consistent and pure water supplies
Recycles nutrients and wastes
Modifies the Atmosphere
Provides habitat for numerous soil organisms
Basic engineering medium
What are the differences between top soil and sub soil - Answers -Topsoil is the
surface layer or "A" horizon. Plant roots go her
Subsoil is the "B" horizon. Often has more clay and con provide water in a drought
Characterize the ways in which soils (the pedosphere) interact with the
lithosphere,hydrosphere, biosphere, and atmosphere - Answers -Lithosphere: Soil
particles
Hydrosphere: Soil water
Biosphere: Organic matter
Atmosphere: Soil air
Characterize the four primary constituents of soils: minerals, organic matter, water, and
air - Answers -Minerals: 45%
Organic matter: 5%
Water: 20-30%
Air: 20-30%
What are the five ways that human activity can diminish soil quality - Answers -Water
erosion
Salt accumulation
Soil organic matter depletion
Diminished soil fertility
Chemical contamination
What is the difference between rocks and minerals? - Answers -A mineral is a naturally
occurring, inorganic solid with a definite chemical composition and a crystalline structure
formed by geological processes. A rock is a mixture of one or more minerals whereas a
rock may also include organic remains and mineraloids.
What is the difference between primary and secondary minerals? - Answers -Primary
minerals are formed as molten lava solidifies and are NOT chemically alerted
, Secondary minerals are re-crystallized products of chemical alteration of primary
minerals
What is the difference between physical weathering and chemical weathering? -
Answers -Physical weathering examples:
Disintegration
Temperature
Water, wind, ice
Organisms
Chemical weathering examples:
Alters composition of rocks and minerals
Conversion of primary to secondary minerals
hydrolisis
carbonate
What are the five soil forming factors? - Answers -Parent materials
Climate
Biota
Topography
Time
What is the relationship between residual, transported and organic
parent materials? - Answers --Residual parent materials are formed in place
-Transported parent materials are moved and redeposited in 6 different ways
- Organic materials form in wet places where plant growth exceeds the rate of
decomposition
How do temperature and effective rainfall influence soil formation? - Answers -Because
as rainfall increases, chemical and physical weathering increases profile depth, nutrient
loss, horizonation, acidity increases
How do plants and animals influence soil formation? - Answers -They're important for:
- Chemical weathering
- OM Accumulation
- Profile mixing
- Aggregate stability
What is the rate of soil formation?
How much soil would form over 100 years? - Answers -.004 mm/y
.4mm
What is the order of the master horizons? - Answers -O, A, E, B C R
What is the "O" master horizon - Answers -Organic surface layer
What is soil? - Answers -A natural body consisting of layers of mineral and organic
materials of variable thickness
What are the six key functions of soils in ecosystems - Answers -Serves as a natural
medium
Provides consistent and pure water supplies
Recycles nutrients and wastes
Modifies the Atmosphere
Provides habitat for numerous soil organisms
Basic engineering medium
What are the differences between top soil and sub soil - Answers -Topsoil is the
surface layer or "A" horizon. Plant roots go her
Subsoil is the "B" horizon. Often has more clay and con provide water in a drought
Characterize the ways in which soils (the pedosphere) interact with the
lithosphere,hydrosphere, biosphere, and atmosphere - Answers -Lithosphere: Soil
particles
Hydrosphere: Soil water
Biosphere: Organic matter
Atmosphere: Soil air
Characterize the four primary constituents of soils: minerals, organic matter, water, and
air - Answers -Minerals: 45%
Organic matter: 5%
Water: 20-30%
Air: 20-30%
What are the five ways that human activity can diminish soil quality - Answers -Water
erosion
Salt accumulation
Soil organic matter depletion
Diminished soil fertility
Chemical contamination
What is the difference between rocks and minerals? - Answers -A mineral is a naturally
occurring, inorganic solid with a definite chemical composition and a crystalline structure
formed by geological processes. A rock is a mixture of one or more minerals whereas a
rock may also include organic remains and mineraloids.
What is the difference between primary and secondary minerals? - Answers -Primary
minerals are formed as molten lava solidifies and are NOT chemically alerted
, Secondary minerals are re-crystallized products of chemical alteration of primary
minerals
What is the difference between physical weathering and chemical weathering? -
Answers -Physical weathering examples:
Disintegration
Temperature
Water, wind, ice
Organisms
Chemical weathering examples:
Alters composition of rocks and minerals
Conversion of primary to secondary minerals
hydrolisis
carbonate
What are the five soil forming factors? - Answers -Parent materials
Climate
Biota
Topography
Time
What is the relationship between residual, transported and organic
parent materials? - Answers --Residual parent materials are formed in place
-Transported parent materials are moved and redeposited in 6 different ways
- Organic materials form in wet places where plant growth exceeds the rate of
decomposition
How do temperature and effective rainfall influence soil formation? - Answers -Because
as rainfall increases, chemical and physical weathering increases profile depth, nutrient
loss, horizonation, acidity increases
How do plants and animals influence soil formation? - Answers -They're important for:
- Chemical weathering
- OM Accumulation
- Profile mixing
- Aggregate stability
What is the rate of soil formation?
How much soil would form over 100 years? - Answers -.004 mm/y
.4mm
What is the order of the master horizons? - Answers -O, A, E, B C R
What is the "O" master horizon - Answers -Organic surface layer
