Soil Forming Processes Flashcards
What are soil forming processes?
Are the ways in which soil forming factors combine to form soil
What is the difference between soil formation and weathering?
A soil forming processes is a building up process and weathering is a breaking down process.
What is mature, stable soil?
Soil that has developed horizons by natural soil forming processes
What happens in the O horizon
It is the first horizon
It contains humus
What happens in the A horizon
It is in the second layer
It is called topsoil
It is darker in colour
It contains many minerals
What happens in the E- horizons?
It is the third horizon
It is lighter in colour
Elluviation occurs here
Leaching occurs here
Contains aluminium and iron
What occurs in B-horizon
Illuviation takes place
Fourth horizon
It is named subsoil
Enriched with calcium carbonate
What occurs in C- horizons?
Just above the bedrock
What would have happened if particles of surface soil don’t match with bedrock?
The soil must have been blown away from its original place to another
Name factors influencing soil forming processes
Mineralization
Humification
Leaching
Luviation
Plinthite
Bioturbation
Inversion
What is mineralization?
Mineralization is the release of minerals from the soil by decomposition.
What are the 2 most important micro organisms in the mineralization process?
Bacteria and fungi
What is the function of bacteria and fungi in the mineralization process?
They break down simple organic matter into their simplest form or building block
What is humification?
Humification is the process whereby micro organisms produce humus through the decomposition process
Name 5 agents of humification
Bacteria, fungi, termites, earthworms and ants
What is the function of humus?
It binds the soil particles together
What is Leaching?
Is it the process where soluble material is taken out of the soil in a solution
Which soil is more prone to leaching?
Sandy soil, because water moves through it much faster
What is percolation?
Liquid filtering through q substance
What is Luviation
It is the downward movement of substances through the soil
Name the two types of luviation
Elluviation
Illuviation
What is Elluviation
Is the removal of organic and inorganic substances in the soil, is driven by the downward movement of water
What is illuviation
Is it the downward movement of material, especially fine particles
What does elluviation result in?
The development called podzols
What is plinthite?
A horizon of oxidized iron that develops into the subsoil
In what places is it prone to happen more?
Places that have fluctuating water tables
How does iron in plinthite occur?
When soils become waterlogged, iron in the soil is reduced because of absence of air. When water tables decrease iron in the soil is oxidized. The iron is distributed randomly in the soil.
What are the two types of plinthite?
Hard plinthite
Soft plinthite
Differentiate between hard plinthite and soft plinthite
Soft plinthite is still permeable to rising water whereas Hard plinthite does not allow water to penetrate through it
What is inversion?
Are soils that contain high inorganic content and very little organic content
Where do inversions occur
In areas where the is distinct wet and dry seasons
What are the properties of inversions?
Shrinking and swelling properties
What is Bioturbation?
Is the result of disturbance caused by living organisms inside and outside sedimentary
What is a cast
Material thrown out into the surface
How does bioturbation occur
When organisms leaving in the soil cast out substances and bring in new organisms into the soil. This churns and mixes organisms in the soil.
