Soil Formation

Question 1

How does soil formation begin?

Answer 1

Rock mineral and organic matter combination

Question 2

Combination of rock mineral and organic matter…

Answer 2

Rock minerals cannot support plant growth, organic matter not structurually sound

Question 3

Volume ratio of soil…

Answer 3

RM/OM 50% whilst pores the other 50%

Question 4

What determines physical properties of soil?

Answer 4

Mineral compostion of the parent rocks

Question 5

What are carbonate rocks ade of?

Answer 5

Limestone and chalk made of prehistoric animals, whilst coal of plants

Question 6

How do silica?silcates form?

Answer 6

Silicon combines with O2, the less the easier they break up

Question 7

What is silica content based on?

Answer 7

Magma solidifcation,

Question 8

Rock classifications based on silica…

Answer 8

Ultrabasic -45
Basic - 45-55
Intermediate 55-65
Acidic -65-85

Question 9

Fractional Crystallisation

Answer 9

Removal of early formed crystals from homogenous magma so these crystals prevented from further reaction with the residual melt

Question 10

SO2 formation…

Answer 10

Foun in silica rich magma formed by fractional crystallisation associated with continental crust, then magma rise and cooling

Question 11

What is silica enrichment in magma based on?

Answer 11

Quartz, feldspar and micas high melting points, crystalling first

Question 12

Bowens Reaction Series

Answer 12

Explains order of mineral crystallisation with cooling

Question 13

Types of weathering?

Answer 13

Physical
Chemistry

Question 14

Example of physical weathering?

Answer 14

Different mineral compositon, different rates of thermal expansion

Question 15

What causes exfoliation?

Answer 15

Temperature difference between inner-outer parts of rock causes

Question 16

Example of mechancial weathering…

Answer 16

Freeze-thaw

Question 17

Examples of chemical weathering…

Answer 17

Hydrolysis, carbonation, hydratio, dissolution, oxidation/reduction

Question 18

Carbonation

Answer 18

This is caused by biological activity with CO2 respiration and dissolution in H2O forming carbonic acid

Question 19

Hydration

Answer 19

This is mineral water absorption without ion formation

Question 20

Dissolution

Answer 20

This is minerals dissolving in water like NaCl and KCl

Question 21

Oxidation/Reduction

Answer 21

This is the take up and removal of oxygen or electrons

Question 22

Soil Organic Matter

Answer 22

All dead and living life, based on carbon content being 58% of total weight of organic matter

Question 23

How does OM contribute to soil?

Answer 23

Binds soil particles in to aggreagtes, supplies nutrients to plants

Question 24

Colloidal Particles

Answer 24

Form electrostatically with water and minerals and organic matter

Question 25

What does OM include?

Answer 25

Microbial biomass, decaying organic matter

Question 26

Hydrophobic Interactions

Answer 26

Repel water, allowing hydrophobic organic mollecles to associate with each others

Question 27

Extracellular Polymeric Substances

Answer 27

Produced by microbes bind soil particles together

Question 28

Chemical groups involved in soil...

Answer 28

Hydroxyl, amino and carboxyl groups interact with soil minerals

Question 29

What is SOM made of?

Answer 29

Hemi/Cellulose Proteins/Amino acids 5% Lignin 15% Fats/waxes 1-5%

Question 30

What does SOM accumulation depend on?

Answer 30

Plants

Question 31

How do plants form soils?

Answer 31

Primary colonisers of microorganisms in water are rqeuired like nitrogen fixers

Question 32

How do lichens colonise?

Answer 32

Surplus nutrients passed to fungi frfom N2 fixers releasing acidic compounds breaking down mineral rock, releasing minerals for algae

Question 33

Example of soil condition climate variability...

Answer 33

Upland UK soils being acidic supporting Ericaceae being acid-tolerant, resistant to microbial attack due to high lignin

Question 34

Three types of soil...

Answer 34

Sand(0.06-2mm) Silt Clay (2mm)

Question 35

Primary cause of chemical release from rock?

Answer 35

Hydration, hyrdolysis and dissolution

Question 36

What can release priamry nutrients do?

Answer 36

Recrystallise forming secondary clay minerals,

Question 37

How are clays classified?

Answer 37

Alternating Alo2 and silica sheets

Question 38

Humus

Answer 38

Conglomerate of organic material formed by humification

Question 39

Layetrs of Soil...

Answer 39

O Horizon A Horizon E Horizon B Horizon

Question 40

How is the O horizon divided?

Answer 40

Litter, fermentation and humic layers

Question 41

How does Mull form?

Answer 41

Neutral/acidic oconditions, mineralise residues and high soil organisms break down OM, mixing with underlying mineral says

Question 42

Types of vertical movment?

Answer 42

Leaching and Eluviation

Question 43

What does leaching do?

Answer 43

Removes soluble compounds under extreme weathering like humid tropics, weathering clay

Question 44

5 Soil forming cators by Hans Jenny...

Answer 44

Climate, parent material, topography, organisms and time

Question 45

What are four types of soil profile?

Answer 45

Podzol Gleysol Ferrasol Histosol

Question 46

Podzol

Answer 46

Foudn in cool, humid and temperate regions, containing large O horizon

Question 47

Gleysol

Answer 47

Found in northern latitudes from drainage impairemnt, from waterlogging

Question 48

Ferralsol

Answer 48

Occupy tropics with high temperature and rainfall like enctral africa and south america

Question 49

Histosol

Answer 49

Peats, covering Northern Europe, Canada and Russia.