Soil Flashcards
What is a soil?
Soil is a naturally occurring thin layer of material on the earth’s surface, that is a medium in which vegetation grows
What are the six factors that affect soil formation?
Parent material Climate Relief Drainage Vegetation cover Passage of time
What is parent material? How does it contribute to soil?
Parent material is the material the soil is formed from. It controls the depth, texture, drainage and quality of the soil
Describe three ways that climate can influence soil formation
- Climate influences the rate of weathering of the parent rock
- It affects the type of vegetation that grows in an area
- If rainfall is light or evapotranspiration is greater than precipitation, capillary action begins and water and minerals are drawn to the surface
What is a soil profile?
The complete set of vertical sequence of layers of the soil
What is a horizon?
A layer of soil
What order are the horizons in?
O A E B C R (Only An Elephant Baby Can Rest)
What is the O horizon?
It’s the organic horizon and has loose and partly decayed organic matter (humus)
What is the A horizon?
Mineral matter mixed with some humus
What is the E horizon?
Has light coloured mineral particles and is a zone of eluviasion and leaching
What is the B horizon?
Accumulation of clay, transported from above
What is the C horizon?
Partially altered parent material
What is the R horizon?
Unweathered parent material
What are the characteristics of ferrasols?
- Red/yellow due to metal oxides (iron and aluminium)
- Geologically old parent material
- Found in humid/tropical climates
- Have rainforests on them
- Only the top few cm are fertile due to metals and rainfall leaching minerals
What are the characteristics of cambisols?
- Brown earth soils
- Not particularly fertile
- Little humus
- Clay layer/salts/oxides
What are the characteristics of fluvisols?
- Very fertile
- Deposition of alluvium of the flood plain
- Humus and minerals
- Layers of deposition
What are the characteristics of vertisols?
- Dark brown/black heavy clay
- Not much humus
- Dry and crack during any season
- Low permeability
- Seasonal (sticky when wet, hard when dry)
What are the characteristics of leptosols?
- Desert soils
- Shallow
- Lack organic material
- Soluble soils
- Not fertile
- Little evidence of soil forming (no layers)
What are the characteristics of andosols (volcanic soils)?
- Very porous (lots of holes) and dark
- Volcanic parent material
- Rich in nutrients and minerals
- Good ability to hold water
- High aluminium content making phosphates unavailable
What does the soil type in the RNDB depend on?
The climate and parent material/rock that is under the ground and the vegetation that grows on it
Where are ferrasols found?
Uganda (mainly)
Where are cambisols found?
Sudan
South Sudan
Egypt
Where are fluvisols found?
North Egypt
River Nile
Where are vertisols found?
Sudan
South Sudan
West Ethiopia
Where are leptosols found?
Egypt
Where are andosols/volcanic soils found?
Ethiopia
Blue Nile Valley
