EVR 2001 FINAL EXAM QUESTIONS AND ANSWERS
What is soil degradation? - Answers :A reduction in the capacity of soil to support plant
life and to perform ecosystem functions.
What 4 things do soils provide? - Answers :Supporting crop growth
Filtering water
Helping Earth's nutrient cycles
Exchanges of gases
What is the parent material?
Where can parent material be deposited from? - Answers :Mineral material of the soil
Can be from wind, water, or ice
What is weathering? - Answers :Physical and chemical breakdown of parent material
into smaller fragments.
Know the relative sizes of gravel, sand, silt, and clay (Figure 11-3) - Answers :Gravel:
larger than sand (rocks)
Sand:
Silt:
Clay: smallest
What are oxisols? - Answers :Soils of tropical and subtropical rain forests.
What are hydric soils? - Answers :These soils indicate a wetland or aquatic site and are
used to delineate wetland boundaries for development or protection.
For their best growth, plants need what 5 things? - Answers :Root environment that
supplies mineral nutrients, water, oxygen, near neutral pH, and low salinity.
What is soil fertility? - Answers :Soils ability to support plant growth.
Why doesn't weathering (which releases nutrients) support normal plant growth?
So where do the nutrients that support plant growth in ecosystems come from? -
Answers :Nutrients become available through rock weathering but it is much too slow
for plant growth.
From the breakdown and release of nutrients from detritus.
,What 3 things do stomata exchange? - Answers :Water vapor and oxygen exit, carbon
dioxide enters.
What 3 attributes of soil are significant in its ability to deal with water? - Answers
:Infiltration (water soaks into soil)
Water-holding capacity (ability to hold water after it infiltrates)
Evaporative water loss (depletes soil of water)
Soil holds carbon from where? - Answers :From leaf litter and dead organisms (3x as
much as held in the atmosphere and plants)
Why aren't sandy soils good soils?
Why aren't clays good soils? - Answers :Sand soil has poor water holding capacity and
dries out quickly. This precludes it from being a choice for soil agriculture.
Clay soils don't allow infiltration or aeration.
In the mutually supportive relationship between plants and soils, what are 3 ways in
which plants support/protect soil? - Answers :Plants support soil organisms since most
detritus come from green plants.
Plants reduce erosion and evaporative water loss.
Without these advantages, then mineralization occurs, reducing the amount of topsoil.
What are 2 examples of organic fertilizer? - Answers :Plant and animal wastes (manure
and compost).
What is an inorganic fertilizer? - Answers :Nutrients without organic compounds (does
not support soil organisms or build soil structure).
What is one of the most crucial forms of soil degradation? - Answers :Erosion (soil and
humus particles are picked up and carried away by water and wind).
What is gully erosion? - Answers :Water joins into rivulets an streams, waters greater
volume, velocity, energy remove soil an results in formation of gullies.
When it comes to practices that cause erosion, what are the 3 discussed in the textbook
and in class? - Answers :Overcultivation
Overgrazing
, Deforestation
What is the drawback of plowing?
How does crops rotation help this issue? - Answers :Exposes soil to wind and water
erosion; causes splash erosion (raindrops break up the clumpy structure of topsoil),
decreases aeration and infiltration, evaporative water loss is increased.
Crop rotation is sustainable (planting a cash crop one year but other years planting hay
and clover which fixes nitrogen and adds organic matter).
What is the broader ecological impact of overgrazing? - Answers :Plants can't keep up
with consumption, grasses lea to erosion and barren land.
Livestock compete with native animals for food, reducing the population of native
species.
Livestock pollute waterways with sediments and their waste.
Do forests continue to be cleared at high rates today?
When is the problem particularly acute? - Answers :Tropical soils (oxisols) lack nutrients
due to leaching, rains wash the thin layer, or humus, away leaving only the nutrient-poor
subsoil.
Dryland ecosystems are defined by what? - Answers :Drylands cover 41% of Earth's ice
free land, They are defined by precipitation not temperature.
As the erosion of topsoil diminishes a soil's capacity to retain water and nutrients,
drylands become what? - Answers :Deserts
What does desertification mean and what does it NOT mean? - Answers :The soils
ability to retain water and nutrients is reduced; does not mean the spread of deserts.
Know the 3 methods of irrigation discussed in the textbooks and in class. - Answers
:Flood irrigation (water flows into canals in fields) Most wasteful.
Center-pivot irrigation (water is pumped from a well into a giant pivoting sprinkler)
Drip irrigation (tubes take water directly to plants) More water conserving
What is salinization?
Why would this occur if we use freshwater to irrigate? - Answers :Salts accumulate in
and on the soil to the point where plants can't grow.
What is soil degradation? - Answers :A reduction in the capacity of soil to support plant
life and to perform ecosystem functions.
What 4 things do soils provide? - Answers :Supporting crop growth
Filtering water
Helping Earth's nutrient cycles
Exchanges of gases
What is the parent material?
Where can parent material be deposited from? - Answers :Mineral material of the soil
Can be from wind, water, or ice
What is weathering? - Answers :Physical and chemical breakdown of parent material
into smaller fragments.
Know the relative sizes of gravel, sand, silt, and clay (Figure 11-3) - Answers :Gravel:
larger than sand (rocks)
Sand:
Silt:
Clay: smallest
What are oxisols? - Answers :Soils of tropical and subtropical rain forests.
What are hydric soils? - Answers :These soils indicate a wetland or aquatic site and are
used to delineate wetland boundaries for development or protection.
For their best growth, plants need what 5 things? - Answers :Root environment that
supplies mineral nutrients, water, oxygen, near neutral pH, and low salinity.
What is soil fertility? - Answers :Soils ability to support plant growth.
Why doesn't weathering (which releases nutrients) support normal plant growth?
So where do the nutrients that support plant growth in ecosystems come from? -
Answers :Nutrients become available through rock weathering but it is much too slow
for plant growth.
From the breakdown and release of nutrients from detritus.
,What 3 things do stomata exchange? - Answers :Water vapor and oxygen exit, carbon
dioxide enters.
What 3 attributes of soil are significant in its ability to deal with water? - Answers
:Infiltration (water soaks into soil)
Water-holding capacity (ability to hold water after it infiltrates)
Evaporative water loss (depletes soil of water)
Soil holds carbon from where? - Answers :From leaf litter and dead organisms (3x as
much as held in the atmosphere and plants)
Why aren't sandy soils good soils?
Why aren't clays good soils? - Answers :Sand soil has poor water holding capacity and
dries out quickly. This precludes it from being a choice for soil agriculture.
Clay soils don't allow infiltration or aeration.
In the mutually supportive relationship between plants and soils, what are 3 ways in
which plants support/protect soil? - Answers :Plants support soil organisms since most
detritus come from green plants.
Plants reduce erosion and evaporative water loss.
Without these advantages, then mineralization occurs, reducing the amount of topsoil.
What are 2 examples of organic fertilizer? - Answers :Plant and animal wastes (manure
and compost).
What is an inorganic fertilizer? - Answers :Nutrients without organic compounds (does
not support soil organisms or build soil structure).
What is one of the most crucial forms of soil degradation? - Answers :Erosion (soil and
humus particles are picked up and carried away by water and wind).
What is gully erosion? - Answers :Water joins into rivulets an streams, waters greater
volume, velocity, energy remove soil an results in formation of gullies.
When it comes to practices that cause erosion, what are the 3 discussed in the textbook
and in class? - Answers :Overcultivation
Overgrazing
, Deforestation
What is the drawback of plowing?
How does crops rotation help this issue? - Answers :Exposes soil to wind and water
erosion; causes splash erosion (raindrops break up the clumpy structure of topsoil),
decreases aeration and infiltration, evaporative water loss is increased.
Crop rotation is sustainable (planting a cash crop one year but other years planting hay
and clover which fixes nitrogen and adds organic matter).
What is the broader ecological impact of overgrazing? - Answers :Plants can't keep up
with consumption, grasses lea to erosion and barren land.
Livestock compete with native animals for food, reducing the population of native
species.
Livestock pollute waterways with sediments and their waste.
Do forests continue to be cleared at high rates today?
When is the problem particularly acute? - Answers :Tropical soils (oxisols) lack nutrients
due to leaching, rains wash the thin layer, or humus, away leaving only the nutrient-poor
subsoil.
Dryland ecosystems are defined by what? - Answers :Drylands cover 41% of Earth's ice
free land, They are defined by precipitation not temperature.
As the erosion of topsoil diminishes a soil's capacity to retain water and nutrients,
drylands become what? - Answers :Deserts
What does desertification mean and what does it NOT mean? - Answers :The soils
ability to retain water and nutrients is reduced; does not mean the spread of deserts.
Know the 3 methods of irrigation discussed in the textbooks and in class. - Answers
:Flood irrigation (water flows into canals in fields) Most wasteful.
Center-pivot irrigation (water is pumped from a well into a giant pivoting sprinkler)
Drip irrigation (tubes take water directly to plants) More water conserving
What is salinization?
Why would this occur if we use freshwater to irrigate? - Answers :Salts accumulate in
and on the soil to the point where plants can't grow.
