An Introduction to soil systems for the IB Environmental Systems and Societies course

1. Topic 5: Soil systems and terrestrial
food production systems and societies
5.1: Introduction to soil systems
5.1: Introduction to
soil system
Part 1

2. Topic 5: Soil systems and terrestrial
food production systems and societies
5.1: Introduction to soil systems
city and resource use
l System
re:
rt of the lithosphere
life processes and soil
g processes both take
Soils are:
The part of the
lithosphere where life
processes and soil
forming processes
both take place.

3. Topic 5: Soil systems and terrestrial
food production systems and societies
5.1: Introduction to soil systems
What is soil made from?
Soils can be thought of as being made up of four main
components.
Mineral particles mainly from the underlying rock
Organic remains that have come from the plants and
animals
Water within spaces between soil grains
Air within the soils grains

4. Topic 5: Soil systems and terrestrial
food production systems and societies
5.1: Introduction to soil systems
Soil profile
If you dig a trench in the ground, the
side of the trench creates a soil
profile, a cross section.
This profile changes as it goes down
from the surface towards the
underlying base rock.

5. Topic 5: Soil systems and terrestrial
food production systems and societies
5.1: Introduction to soil systems
Organic - O Horizon
Iron Pan
Ash like leached
A - Horizon
Soil section through a river bank showing leaching
Soil profile
If you dig a trench in the ground, the
side of the trench creates a soil
profile, a cross section.
This profile changes as it goes down
from the surface towards the
underlying base rock.

6. Topic 5: Soil systems and terrestrial
food production systems and societies
5.1: Introduction to soil systems
can be divided into HORIZONS
ded organic material such as leaf litter
The soil profile can be divided into HORIZONS
O - newly added organic material such as leaf litter

7. Topic 5: Soil systems and terrestrial
food production systems and societies
5.1: Introduction to soil systems
n many soils humus builds up. Humus forms
d organic matter and often mixed with fine
The soil profile can be divided into HORIZONS
A - where in many soils humus builds up. Humus forms
from partially decomposed organic matter and often mixed
with fine mineral particles

8. Topic 5: Soil systems and terrestrial
food production systems and societies
5.1: Introduction to soil systems
The soil profile can be divided into HORIZONS
B - the layer where soluble minerals and organic matter
tends to be deposited from the layer above by leaching. In
particular clay and iron salts can be deposited in this
horizon

9. Topic 5: Soil systems and terrestrial
food production systems and societies
5.1: Introduction to soil systems
er is mainly unaltered rock from which the
The soil profile can be divided into HORIZONS
C - This layer is mainly unaltered rock from which the soil
forms

10. Topic 5: Soil systems and terrestrial
food production systems and societies
5.1: Introduction to soil systems
How do soils form?
S = ƒ cl. o. r. p. t. . . .
S = soil, cl = climate, o = organisms, r = relief (land
shape, topography), p = parent material, t = time
(Jenny: 1941)

11. Topic 5: Soil systems and terrestrial
food production systems and societies
5.1: Introduction to soil systems
How do soils form?
S = ƒ cl. o. r. p. t. . . .
Soils are a result of interactions between
Climate, Organisms, Relief, Parent material and
Time