Soil Processes

Question 1

How does soil form?

Answer 1

In horizons:
Leaf litter
O horizon (humus)
Varying number of other horizons
Parent material

Question 2

Define ‘leaching’

Answer 2

A process where water (from precipitation) moves through the soil (percolation) and removes the soluble nutrients/minerals from the soil.
This occurs in areas with high precipitation (eg, Uganda)

↘↘↘↘↘↘ - precipitation
___________ - top soil layer
↓↓↓↓↓↓↓↓↓↓↓↓↓ - movement of water takes soluble nutrients

Question 3

Define ‘humification’

Answer 3

A process where organic material (dead plants) decomposes and adds nutrients to the soil. This is the humus layer.
This occurs in areas that are humid (eg, Uganda and equatorial locations)

^^^^^^^^^ - leaf litter
_______ - top soil layer
↓↓↓↓↓↓↓↓ - leaf litter decomposing

Question 4

Define ‘ferralisation’

Answer 4

A process where water moving through the soil leaves behind (the insoluble minerals) iron and aluminium

Question 5

Define ‘capillary action’

Answer 5

A process where water moves upwards through the soil, transporting soluble minerals with it (eg, salt)