Chapter 5: Soil Systems and Society

Question 1

Soil

Answer 1

The upper layer of Earth, made up of organic matter, minerals, nutrients, gases, liquids, living organisms, sand, clay, silt

Question 2

Why is soil important?

Answer 2

It stores and transfers heat and is not renewable – everything comes from it: clothes, crops, food. Natural resources: diamonds, gold, silver, oil, natural gas (methane).
It is a habitat for many organisms and provides nutrients for producers and filters water.

Question 3

Where does soil come from

Answer 3

Weathering

• physical: freeze; water; wind
• chemical
• biological: plants

Question 4

Levels of soil

Answer 4

Humus (or organic topsoil)
Eluviated horizon
Subsoil
Parent material
Bedrock

Question 5

How does soil form?

Answer 5

Very slow process:

• Weathering of rock (mechanical)
• Deposition of sediments by erosion (mechanical)
• Decomposition of organic matter (chemical)

Question 6

Soil system

Answer 6

Soil systems are dynamic.
Storages: organic matter, organisms, nutrients, minerals, air, and water.
Transfers within the soil: biological mixing, translocation (movement of soil particles in suspension), and leaching (minerals dissolved in water move through soil).
Inputs: organic material including leaf litter and inorganic matter from parent material, precipitation, and energy.
Outputs: Uptake by plants and soil erosion.
Transformations: decomposition, weathering, and nutrient cycling.

Question 7

Cycles

Answer 7

Nitrogen and carbon cycles.

Question 8

Soil diagrams

Answer 8

Triangle diagram showing soil texture based on particles. Can determine how much clay, silt and sand is in the soil.

Question 9

Soil permeability

Answer 9

The rate at which air and water can flow through the layers of soil.

Question 10

Soil porosity

Answer 10

The space between the soil particles.

Question 11

Different soil permeabilities and porosities.

Answer 11

Clay soils – High porosity (micropores), low permeability, high nutrients but inaccessible, low leaching.
Sandy soils – lower porosity (fewer macro), high permeability, high leaching
Loam soils – Best of both, ideal for agriculture

Question 12

Acidification of soil

Answer 12

Acid precipitation increases acidity near urban areas
Clay soils often have high acidity due to absorption of water
Causes leaching of potassium, magnesium and ammonium
Causes aluminum and iron to become more available to plants which are toxic

Question 13

Soil sustainability

Answer 13

Fertile soil is a non-renewable resources
Fertile soil has enough nutrients for healthy growth (N,P,K)
Nutrients are leached from soil by water
Nutrients are lost when crops are harvested
Replace nutrients with fertilizers
More sustainable method of replacing nutrients is by crop rotation, planting legumes and using organic fertilizers

Question 14

Commercial agriculture

Answer 14

large scale production of crops and livestock for sale

Production for profit
Maximizing yield
High level of technology
Monocultures
High inputs of energy
Extensive- more land with lower planting
Intensive – use land more intensively

Question 15

Substinence agriculture

Answer 15

farming for self-sufficiency to grow enough for a family

Production food for family
No surplus
Human and animal labor
Mixed crops
Low inputs of energy
Cash cropping

Question 16

Pastoral farming

Answer 16

Raising animals on grass and land not suitable for crops suitable for crops

Question 17

Arable farming

Answer 17

Growing crops on good soil to eat directly or feed to animals

Question 18

Mixed farming

Answer 18

Crops and animals
Animal waste used to fertilize crops
Crops used to feed animal

Question 19

Farming systems in detail

Answer 19

Inputs – fertilisers, water, pest control, labour, seed etc.
Outputs – food quality, yield, pollutants, transport, processing, packaging etc.
System characteristics – diversity, sustainability etc.
Environmental impacts – pollution, habitat/biodiversity loss, soil erosion/degredation, desertification, disease etc.
Socio-economic factors – Subsistence/commercial, traditional?, local/export, quality/quantity

Question 20

Extensive vs. Intensive farming

Answer 20

Intensive Farming is a farming method that uses higher inputs and advanced agricultural techniques to increase the overall yield. In contrast, Extensive Farming is one in which more and more land is brought under cultivation to increase the output produced.

Question 21

Terrestial vs. aquatic

Answer 21

Terrestrial is a more efficient use of solar energy (1st/2nd trophic level)
Less solar energy reaches aquatic systems (reflection and absorption by water)
Aquatic often higher trophic level (4+)
Aquatic systems more efficient in terms of passing energy along food chain
More skeletal waste in terrestrial (terrestrial animals need more substantial bones to support themselves on land)

Question 22

Soil degradation

Answer 22

Processes that take away the soil (erosion).

• No or little vegetation on the soil.
• Wind and water.

Processes that make the soil less suitable for use.

• Loss of chemicals/nutrients (leaching)
• Addition of chemicals (pollution)

Generally commercial industrialized food production systems reduce soil fertility more than small-scale subsistence farming.

Question 23

Soil erosion

Answer 23

Movement of soil, especially surface litter and topsoil

Two main agents of erosion

• Wind
• Flowing Water

Question 24

Sheet wash

Answer 24

Large areas of surface soil are washed away during heaving rain.
Can include landslides

Question 25

Gullying

Answer 25

Channels develop on hillsides following rainfall.

Over time they get deeper and deeper.

Question 26

Wind erosion

Answer 26

Drier soils have the top layers consistently removed

Question 27

HUman activities that lead to soil degradation.

Answer 27

Overgrazing
Overcropping
Deforestation
Unsustainable agriculture
Urbanization

Question 28

Monoculture farming

Answer 28

Monoculture farming is a form of agriculture that is based on growing only one type of a crop at one time on a specific field. In contrast, a polyculture system assumes that a field is sown with two or more crops at a time

Question 29

The pedosphere

Answer 29

The pedosphere is the skin (or the soil cover) of the Earth and only develops when there is a dynamic interaction between the atmosphere (air in and above the soil), biosphere (living organisms), lithosphere (unconsolidated regolith and consolidated bedrock) and the hydrosphere (water in, on and below the soil).

Question 30

The Green Revolution

Answer 30

the set of research technology transfer initiatives occurring between 1950 and the late 1960s, that increased agricultural production worldwide.

Question 31

Example of desertification

Answer 31

The Sahel Draught (Case study)

Question 32

Transfer within soil profile

Answer 32

biological mixing by soil animals/earthworms / leaching / seepage / capillary action / drainage / percolation / infiltration / eluviation / absorption of minerals/water by living organisms.

Question 33

Transformations within soil profile

Answer 33

decomposition;
humus formation/humification of organic matter;
weathering of primary minerals/parent rock;
nutrient cycling/nitrogen fixation/nitrification/denitrification/ammonification;
evaporation;
rusting soil.