Soils Flashcards
Soils
What does soil composition depend on? (5)
Parent material
Climate
Other organisms
Topography
Age
Soils
4 Soil horizons?
O horizon
A horizon
B horizon
C horizon
Soils
O horizon (2) =
Leaf litter
Very little mineral
Soils
A horizon (3) =
High organic content
Some mineral
“Top soil”
Soils
B horizon (2) =
Subsoil
Less organics, more minerals
Soils
C horizon (2)
Parent material, rock
Maybe stored water in an aquifer
Soils
Parent material =
example?
Minerals
Serpentine
Soils
Serpentine =
High in heavy metals
Climate
Some rain =
Well developed soil
Climate
A lot or too much rain =
Minerals wash away
Climate
Frost wedging =
Frozen water (ice) breaks apart rocks
Living Organisms
1/1000 of soil is ___
Alive - bacteria
Living Organisms
Decomposers purpose
Make organic molecules available to plants
Living Organisms
Decomposers provide ___ (molecule)
CO2
Topography =
The lay of the land
Topography
Steep slope causes…
Small particles to wash away
Topography
Standing water prevents… (2)
Gas exchange
Limits bacterial activity
Soil Structure
Sand size
0.05mm-2mm
Soil Structure
Sand characteristics (2)
Drains quickly
Holds air
Soil Structure
Sand benefit
Gas exchange
Soil Structure
Sand disadvantage
Nitrogen might be depleted
Soil Structure
Silt size
0.002mm - 0.05mm
Soil Structure
Clay size
Less than 0.002mm
Soil Structure
Clay characteristics (2)
Drains slowly
More empty space
Soil Structure
Clay benefit
More time for plants to absorb water
Soil Structure
Clay disadvantages (2)
Less gas exchange
Less nitrogen availability
Soil Structure
“Best soil” Composition (3)
40% Sand
40% Silt
20% Clay
