week 5 material

Question 1

Why are soils so important?

Answer 1

Directly contributes to a number of Sustainable Development Goals

Question 2

What is Soil security?

Answer 2

the maintenance and improvement of the global soil resource to produce food, fibre and freshwater

Question 3

What is soil?

Answer 3

The uppermost part of the earth’s surface that has been affected by weathering, new mineral formation, organic matter accumulation, erosion and deposition, and that forms the natural medium for the growth of land-based vegetation

Question 4

What are soils characterised by?

Answer 4

horizons, or layers or the ability to support

rooted plants in a natural environment.

Question 5

Why are horizons distinguishable?

Answer 5

result of additions, losses, transfers, and transformations of energy and matter

Question 6

What is the upper limit of soil?

Answer 6

the boundary between soil and air, shallow water, live plants, or plant materials that have not begun to decompose

Question 7

What would be the components of optimal loam soil?

Answer 7

Air 25%
Water 25%
Mineral Particles 45%
Organic Matter 5%

Question 8

What is soil formation a function of?

Answer 8

Soil forming processes

Soil forming factors

Question 9

What are some examples of Additions?

Answer 9

includes organic material (leaf litter, bark etc), dust, solutes, water

Question 10

What is Translocation?

Answer 10

– Vertical and lateral movement of inorganic and organic material between different horizons
– Mostly moved by water, but can be moved by biota
– Main process in forming soil horizons

Question 11

What is Transformation?

Answer 11

soil constituents are chemically or physically modified

Question 12

What are the different soil forming factors?

Answer 12

parent rock
climate
time
Relief
Flora, Fauna and Micro-organismss

Question 13

What are the different parent materials?

Answer 13

• Bedrock
• Transported material
• Organic material

Question 14

What are the different forms of transported material?

Answer 14

– Alluvial sediments (deposited by rivers)
– Colluvial sediments (deposited by
gravity/hillslope)
– Aeolian sediments (deposited by wind)
– Glacial till or periglacial sediments

Question 15

What are the different climate effects?

Answer 15

• Rainfall effects

* Temperature affects

Question 16

effects of temperature on soil?

Answer 16

– Water balance in the soil
– Rates of chemical reactions and decomposition
processes
– Soil biota at all scales

Question 17

What are organisms effects on soils?

Answer 17

• Vegetation
• Cryptogams
• Bioturbation by fauna
• Micro-organisms

Question 18

What is relief?

Answer 18

Configuration of the land surface:
– Topography
– Slope
– Aspect
– Elevation
– Landscape position

Question 19

What are the Four soil forming processes?

Answer 19

Additions, losses, translocations,

transformations

Question 20

What are the Five soil forming factors?

Answer 20

parent material, climate, organisms, relief

and time

Question 21

What are the effects of time on soils?

Answer 21

Thicker horizons that sink deeper
into parent material
Increased iron accumulation making
soils redder or yellower
Increased clay content with depth
Increased acidity (soil with lower
pH)
Nutrient leaching so soil is less
fertile

Question 22

What are the different kinds of soil loses?

Answer 22

– Leaching
– Erosion
– Decomposition of organic matter to form CO2

Question 23

Where does calcification occur?

Answer 23

in low rainfall areas

Question 24

process of Calcification?

Answer 24

• Slight downward leaching of soluble compounds occurs
• Soil water evaporates
• Calcium carbonate precipitates in subsoil

Question 25

What is the process of Podzolisation?

Answer 25

– Organic material on the surface provides a source of
dissolved organic carbon
– Water passes through the organic layer to mobilise
dissolved organic carbon (acidic)
– The acidic solution dissolves insoluble oxides in the
soil
– Fe and Al are mobilised, combined with the organic
extracts and move to the subsoil
– Fe precipitates formed
– Formation of cemented layer

Question 26

What is the process of Salinisation?

Answer 26

– Salts contained in soil the soil profile
– Groundwater rises to near the surface
– Water drawn upwards by capillary action and evapotranspiration
– Salts precipitate as water is evaporated