EAE 09 Soils Flashcards
What part of the soil is the A horizon?
Topsoil
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What part of the soil is the B horizon?
Subsoil
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What part of the soil is the R horizon?
Weathered or decomposed
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What part of the soil is the O horizon?
Organic materials
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What is the definition of soil?
The uppermost part of earth’s surface, that forms a natural median for growth of land based vegetation.
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What is Loam textured soil?
4 points.
Soil that is ideal for plant growth and is:
- 25% Air
- 25% Water
- Biomass/O.M. 5%
- 455 minerals.
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How much of vegetated land is considered degraded?
17% or 1 in 6 hectares.
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What is Humus?
Dark organic matter whose original components can no longer be recognized.
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What is the relationship between air and what in soil?
Water and air take up the same amounts of space in soil and are therefore higher proportions of one mean lower proportion of the other.
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Is all water in soil available to plant why or why not?
No as some water is held in micropores unavailable to plants.
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What are the main factors which influence weathering and erosion?
4 points.
- Rock type
- Topography
- Rainfall
- Wind exposure
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How is surface area affected by the breakdown of a rock?
The more broken down it is the higher the surface area
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What is the primary factor in determining soil formation?
Parent material.
Soil forms much slower from bedrock then it does from alluvium.
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What are the characteristics of alluvial deposits?
2 points.
- Soils follow pattern of sediments.
- Finer soils form further away.
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Why are soils from igneous rocks fertile?
They form a clay rich soil.
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What does temperature affect in soils?
3 points.
- Water balance in the soil.
- Rate of chemical reactions.
- The soil biota present.
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What does temperature and rainfall affect in soils?
6 points.
- Soil depth
- Particle size
- PH
- Organic matter content
- Salt concentration
- Concentration and type of minerals.
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How does evapotranspiration relate to average rainfall?
It is the inverse of the rainfall.
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What are the base cations?
- Ca²⁺
- Mg²⁺
- K⁺
- Na⁺
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What are the characteristics of arid dry?
2 points.
- High evapotranspiration.
- High amounts of mineral leaching
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What are the characteristics of temperate soil?
2 points.
- Moderate leaching
- Moderate evapotranspiration
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What are the characteristics of a Monsoon soil?
2 points.
- Very High soil leaching
- Moderate evapertraperation
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What does soil PH set?
The environment in which plants will grow. Ideal is a fairly neutral soil.
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What is the PH of High rainfall environments?
Low PH(more acidic).
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What is the PH of low rainfall environments?
High PH (more alkaline).
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What are the key characteristics of arid and semi-arid environments?
3 points.
- High soil PH
- Presence of salts
- Low organic matter
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What are the key characteristics of alpine and subalpine environments?
3 points.
- Low PH
- Leached salts
- High levels of organic matter
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What are the key characteristics of tropical environments?
3 points.
- Low PH
- Salts leached
- Low organic matter accumulation
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What is relief?
4 points.
The configuration of the land’s surface. Including the
- Slope
- Aspect(compass direction)
- Elevation
- Landscape position
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How does aspect affect soil in Australia?
North facing slopes are drier and therefore less weathered than the south facing slopes.
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What is the definition of land use?
It is defined as the purpose to which the land cover is committed.
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What is the definition of Land cover?
Land cover refers to the physical surface of the Earth and includes vegetation, soils exposed rocks, water bodies and built environments.
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What is Land management practice?
It is defined as the approach taken to achieve a land use outcome.
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What was the green revolution and how was it achieved?
5 points.
Green revolution was a technological response to food shortage after WWII achieved through:
- Use of fertilizers
- Irrigation
- High yielding varieties
- Double cropping(not waiting a season to replant).
- Use of modern agricultural equipment.
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What were the impacts of the green revolution on soil?
4 points.
- Increased soil and water degradation
- Increased use of water
- Decreased genetic diversity
- Increased use of pesticides and fungicides
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What were the initial impacts on agriculture in Australia?
2 points.
- Removal of vegetation and surface cover causes increased potential for erosion.
- Introduction of hard-hooved animals compounded this effect.
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What kinds of erosion can be caused by water?
3 points.
- Sheet erosion
- Kill erosion
- Gully erosion
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What is Sheet erosion?
Uniform removal of surface of soil by raindrop impact and run off.
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What are Rills?
Channels greater than 30cm deep formed from sheet erosion.
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What is Desertification?
Land degradation in arid, semi-arid and sub-humid areas.
Resulting from climatic variations and human activities.
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What are the causes of Desertification?
4 points.
- Overgrazing
- Over cultivation
- Deforestation
- Poor irrigation practices.
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What are some management and rehabilitation techniques?
6 points.
- Establishing seed banks.
- Maintaining vegetation cover.
- Integrating land and water management
- Re-introduction of selected species
- Counter erosion through terracing
- Addition of soil nutrients.
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