L1: Pedogenesis

Question 1

what is pedogenesis

Answer 1

formation of soils

Question 2

how many laters in the soil profile?

Answer 2

5

Question 3

what are the layers in the soil profile?

Answer 3

Organic horizon (O)

Leached horizon (A)

Accumulation Horizon (B)

Partially weathered horizon (O)

Parent Material (R)

Question 4

What is soil leaching

Answer 4

the downward movement of dissolved mobile plant nutrients in the soil profile following percolating water such as rain or irrigation water

Question 5

What form of iron is present in oxic conditions?

Answer 5

Fe(III) iron oxide

FERRIC IRON

Question 6

What form of iron is present in anoxic conditions?

Answer 6

Fe(II)

FERROUS IRON

Question 7

How does soil form?

Answer 7

The process of gradual weathering and removal of certain elements creating soil

Question 8

What are the characteristics of the leached horizon?

Answer 8

Coarse mineral horizon from which iron, aluminium and clay minerals have been removed

Question 9

what accumulates in the accumulation horizon?

Answer 9

fine organic material, clay minerals and iron oxides

Question 10

What maintains the ecosystem balance in soils?

Answer 10

The combination of living biomass providing nutrients to different plant species which maintains soil fertility, health, biodiversity and biogeochemical cycles

Question 11

What animals (in soil) are ecosystem engineers?

Answer 11

Ants
Termites
Earthworms

Question 12

What is edaphology

Answer 12

The influence of soil properties on life

Question 13

What is the connection between geoecology and pedology?

Answer 13

Plant species can indicate the soil/rock type

Question 14

What type of soils do limestone soils create?

Answer 14

Basic (alkaline) soils

Question 15

What type of soils does gneiss create?

Answer 15

Acidic soils

Question 16

What do differing rock types determine?

Answer 16

• physical structure of the soil and the environment
• soil particulate composition
• nutrient retention
• drainage

Question 17

What are the basic ingredients of soil?

Answer 17

Rock fragments such as
- grit
- silt
- clay
AND organic humus

Question 18

Which soil is ideal for agricultural purposes

Answer 18

Loam

Question 19

What is a soil aggregate/ped

Answer 19

individual soil particles that are stuck together to form larger soil structures

Question 20

What examples of biological structures help to form soil aggregates?

Answer 20

roots and fungal hyphae

however, roots can also break up clay or loam aggregates

Question 21

What causes clay minerals and organic matter to bind?

Answer 21

ionic and van-der-Waals interaction

Question 22

What is van der Waals interaction?

Answer 22

attraction and repulsions between atoms, molecules, as well as other intermolecular forces

Question 23

How does climate impact soil formation

Answer 23

Freezing and thawing can break up rocks, speeding up the soil formation process

Question 24

What are the 3 main phases of soil formation

Answer 24

1) weathering and the build up of organic matter (leaching is an exception)

2) characterised by rapid property changes such as the formation of clays

3) Known as the steady state although leaching input and loses, and organic matter degradation and input are in balance

Question 25

What forms of sedimentary rocks can you have?

Answer 25

Clastic (eg sandstone and shale) chemical (lime stone)

Question 26

What form of metamorphic rocks can you have

Answer 26

foliated (slate) nonfoliated (marble and quartzite)

Question 27

What forms of ingenous rocks can you have?

Answer 27

intrusive (gabbro and granite) extrusive (basalt)

Question 28

what does felsic and mafic/ultramafic desribe?

Answer 28

the colour of rock felsic is lighter rock mafic/ultramafic is darker coloured rock

Question 29

What is the composition of granite and its pH

Answer 29

formed from sandy soils with a clay input from non-local runoff

Question 30

What is the composition of Basalt and its pH

Answer 30

Basic formed from silt and clay soils

Question 31

What is the composition of Sandstone and its pH

Answer 31

Acidic Sandy soils but is dependent on the cementing agent

Question 32

What is the composition of shales and its pH

Answer 32

Basic silts and clays

Question 33

What is the composition of limestone and its pH

Answer 33

Basic Commonly silts but also have a thin clay and sand layer

Question 34

What does autochthonous mean?

Answer 34

Soil derived from local parent rocks (or nearby parent rocks)

Question 35

What does allochthonous mean?

Answer 35

Soils formed with material from elsewhere

Question 36

list examples of allochthonous soil origins and the 'mode of transport'

Answer 36

material moved by air - loess, sands and ash fall material moved by water - exposed lake, river, saltmarsh and mangrove sediments material moved by ice - glacial depositys

Question 37

Types of weathering

Answer 37

Mechanical / Physical Chemical

Question 38

Mechanical / Physical weathering definition

Answer 38

the break down of material due to mechanical / physical processes eg wind, freeze thawing, glaciers

Question 39

chemical weathering definition

Answer 39

the composition of the rock altering due to chemical influences - eg rainwater

Question 40

Are sand and silt chemically resistant? What does that mean?

Answer 40

Yes they are which means they are nutrient poor

Question 41

list examples of chemically altered fragments

Answer 41

silicate claus iron oxide aluminium oxide chemical salts

Question 42

what is lay composed of?

Answer 42

Aluminium and Silica

Question 43

What colour are organic matter rich soils?

Answer 43

dark brown - black

Question 44

Hydrated iron oxides (ferric hydroxides) give what colour soil

Answer 44

yellowish

Question 45

Dehydrated iron oxides (ferric oxyhydroxides) give what colour soil

Answer 45

greyish soils

Question 46

What do white soils indicate?

Answer 46

carbonate deposits

Question 47

What are azonal soils?

Answer 47

mountain soils

Question 48

what is a catena?

Answer 48

the continuous variation of soil and vegetation types down a hillslope

Question 49

what are the features of a catena

Answer 49

Summit area Upper convex slope Main-slope Lower main-slope Concave slope Foot-slope

Question 50

difference between the eluvial and illuvial zone

Answer 50

Eluvial zone is where the downward percolation of water through soil horizons which transports soil content from upper layers to lower levels occurs illuvial zone is where the deposition of this material (illuvial deposit) in lower levels

Question 51

what influences leaching

Answer 51

The quantity of water influences what is leached

Question 52

Which section of the catena has well-drained soils

Answer 52

Colluivial zone

Question 53

what causes soils to vary along slopes

Answer 53

- Drainage conditions - Transport of eroded materials (eg. mass movements, erosion) - Transport of dissolved material

Question 54

Where do you find acidic soils on a slope

Answer 54

At the summit/shoulder of the slope in the eluvial zone

Question 55

Where do you find slightly acidic to neutral soils?

Answer 55

on the main slope in the colluvial zone

Question 56

where do you find neutral to to alkaline (wet) soils

Answer 56

at the foot and toe slope in the illuvial zone

Question 57

What happens if nitrate is leached from the top of the slope (impact on soils)

Answer 57

Hydrogen ions accumulate at the top of the slope making the summit soils more acidic

Question 58

What are the stages of soil developments

Answer 58

Initial weathering and humus input pedogenesis mature soil type under environmental pressures soil catena development

Question 59

what are the stages of vegetation development?

Answer 59

species origin or new site seral development and colonisation climax vegetation under environmental pressures ecotyles / clines

Question 60

what is chelation

Answer 60

Chelation is a type of bonding of ions and the molecules to metal ions

Question 61

List 2 examples of chelating agents and which organisms use them?

Answer 61

Siderophores = Bacteria and Fungi Phytosiderophores = plants

Question 62

Why are oceans iron deficient?

Answer 62

If oxygen is present, iron II is transformed to iron III which is not bioavailable for organisms to ude

Question 63

How is iron III used to treat waste water that is phosphorus rich?

Answer 63

Iron III is added as phosphorus sticks to it and its 'cleans' up the water

Question 64

In which zone is clay lost and in which zone is clay accumulated?

Answer 64

Eluvial zone = clay is lost Illuvial zone = clay is accumulated

Question 65

What do ericoid and arbuscular mycorrhiza do?

Answer 65

They have a symbiotic relationship with the plant which provides it with immunity

Question 66

Thats the difference between ericoid and arbuscular