Geoecology - Soil Flashcards
What is the study of soil called?
Pedology
What % is the earth’s surface covered in soil?
25%
What % of soil is suitable for growing food?
10%
What is soil?
Layer of natural material on the earth’s surface that is capable of plant growth.
How many main ingredients make up soil?
5
Name the 5 main ingredients in soil?
- Mineral matter
- Air
- Water
- Living organisms
- Humus
What % of mineral matter is in soil?
45%
What % of air is in soil?
25%
What % of water is in soil?
25%
What % is organic matter- (living organisms and humus)
5%
Describe mineral material.
- Small pieces of rocks
- Sand, slit, clay
- Pieces broken down by erosion and weathering
Why is air important in soils?
It contains oxygen and nitrogen which are essential for plants and organisms in the soil
Why is water important in soils?
- Contains dissolved minerals
- Plants absorb these minerals through their roots
- Minerals are then defined as nutrients.
What is the role of living organisms?
To break down dead plants and help create humus.
ie. earthworms, woodlice, bacteria, fungi etc.
What is humus?
A black gel-like substance made up of decaying organic matter.
Name three factors that affect the creation of soil.
- Climate
- Vegetation
- Time
What is a soil profile?
A section of soil extending from the surface to the bedrock.
What are the different layers in a soil profile called?
Horizons
Describe O Horizon.
- High % of organic matter (30%)
- Dead plants/animals collect on surface
- Leads to creation of humus
Describe A Horizon.
- Upper layer of soil/ topsoil
- Dark in colour due to humus
- Most organisms live here
Describe B Horizon.
- Called subsoil
- Zone where water percolates through
- Deposits leached minerals
Describe C Horizon.
-Mainly made up of large lumps of partially weathered and decomposed rock.
Describe R Horizon.
- Known as bedrock
- Composed of undisturbed parent rock
Name the six soil characteristics.
- Colour
- Structure
- Texture
- Humus content
- pH value
- Water content
Why do brown and black soils have their colour?
- Due to the presence of humus
- Soils that are rich in humus are very fertile.
Why are grey soils described as ‘washed out’?
- Nutrients have been leached out of them due to rainfall
- Waterlogged and infertile
