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ENVIRO & ECOLOGY > Soils Intro > Flashcards

Soils Intro Flashcards

1
Q

What is soil

A

the soilic material on the Earth’s surface that results from the interaction of weathering and biological activity on the parent material/ hard rock

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2
Q

How is soil made?

A

from the interaction of weathering and biological activity on the parent material/ hard rock

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3
Q

Why study soil?

A

Helps understand wildlife activity, potential and conservation for both plants and animals

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4
Q

What are the 4 principles of soil

A

Water
CO2 sequestration (storage)
Water holding
water purification

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5
Q

If there is less than 50% air and water in soil what does this mean?

A

It is poor soil

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6
Q

What percentage of soil is typically humus/ organic matter?

A

3-5%

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7
Q

What % of soil is sand?

A

10%

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8
Q

What % of soil is clay

A

22%

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9
Q

What % of soil is air?

A

25%

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10
Q

What % of soil is water?

A

25%

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11
Q

What % of soil is silt?

A

15%

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12
Q

What 7 things comprise soil?

A 
water
air
humus
silt
clay
sand
living organisms/ component
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13
Q

Name 3 components of organic matter?

A
  • Cellulose
  • Hemicellulose
  • Lignin
  • Protein
  • Fats, waxes
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14
Q

Name 3 sources of organic matter for agricultural soils

A
  • Crop residues
  • Bulky organic manures
  • Sewage sludge -
  • Green manure
  • Composted urban waste
  • Rotational practice (stubble)
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15
Q

What are the horizontal layers of soil known as?

A

Horizons

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16
Q

What are the A, B and C horizons?

A

A - top soil
B - Subsoil
C - Parent soil

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17
Q

What is the structure of soil horizons (5)

A 
Humus
top soil
subsoil
parent material 
bedrock
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18
Q

Where can the O horizon be found?

A

above top soil in forests

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19
Q

what is the o horizon?

A

organic matter (humus)

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20
Q

Which is the most important nutrient in soil?

A

Nitrogen

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21
Q

Which horizon is nitrogen mainly found?

A

humus layer - O horizon

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22
Q

Name 3 ways soils can be formed

A

Earth movement - earthquakes etc
Changes in sea levels
Volcanic activity
Retreat of glaciers

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23
Q

What are the 3 types of weathering/ erosion that can cause soil formation?

A

Physical
Chemical
Biological

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24
Q

Give an example of physical, chemical and biological weathering

A

Physical = freeze/ thaw, wet/dry, hot/cold, abrasion
Chemical = water disolving rock - i.e: acid dissolution in limstone
Biological - tree roots cracking rocks, earthworms mixing materials, dead organic matter

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25
Q

What are the 5 factors of soil formation?

A 
Organisms
Time
Topography (distribution/ arrangement of the area) 
Climate
Parent material
26
Q

Which is the most important factor in soil formation?

A

Climate

27
Q

How does climate affect soil formation?

A

Affects rate / type of soil
vegetation distribution - therefore nutrient content
precipitation (moisture content)
Temperature - evaporation rate (and vegetation growth, nutrients etc)

28
Q

What conditions lead to leaching?

A

When precipitation exceeds evaporation

29
Q

What is leaching

A

the loss of water-soluble nutrients in soil

30
Q

What do micro and macro organisms do?

A

Micro (bacteria) - help decompose plant litter

Macro (worms, beetles etc) mix litter into soil

31
Q

What influences the nature of humus, vegetation, litter etc

A

higher plants

32
Q

What are 4 benefits of roots in soil

A

contribute to dead organic material
bind soil particles together
redistribute and compress soil
Remove nutrients

33
Q

What are macrobiota

A

the living organisms of a region that are large enough to be seen with the naked eye
i.e: ants, termites, earthworms, beetles, snails, wasps, milipedes

34
Q

What are mesobiota?

A

the intermediate size of soil organisms

i.e: o Springtails, mites, pseudo-scorpions (false scorpion)

35
Q

What are microbiota?

A

bacteria, archaea, protists, fungi, viruses, yeast, cyanobacteria (blue-green algae)

36
Q

How do cyanobacteria help soil health?

A

Fixes nitrogen in soil

37
Q

Which organism helps fix nitrogen in soil

A

Cyanobacteria

38
Q

How does topography influence soil formation?

A

slopes - influence soil thickness, nutrients, erosion, run-off, movement, microclimatic conditions

39
Q

How does time influence soil formation?

A

Soil takes time to form

More time = more nutrients, features and materials can be added to help formation

40
Q

what are the 5 processes of soil formation

A

1) weathering
2) decomposition and humification
3) capillary action - when evaporation exceeds precipitation (reverse leaching)
4) leaching
5) Translocation

41
Q

What is decomposition

A

the breakdown of plant dervived material into its simpler organic constituents – accomplished by enzymes, earthworms, mites and other organisms

42
Q

What is humification

A

the breakdown of plant remains leading to the formation of different types of humus

43
Q

What is the most important BIOLOGICAL PROCESS in soils?

A

humification

44
Q

What are 3 types of humus

A

Mull
Moder
Mor

45
Q

Where are mull, moder and mor found

A

Mull - deciduous woodland
Moder - intermediate
Mor - coniferous woodland or heather moorland (wet, climatic conditions)

46
Q

Which type of humus is found in deciduous and coniferous woodland?

A

Deciduous - mull

coniferous - mor

47
Q

Why is leaching bad for soil?

A

It removes soluble minerals

48
Q

Which types of soils have more leaching?

A

sandy soils - because they are more porous

49
Q

What is translocation?

A

the movement of material in solution or suspension from one horizon to another

50
Q

What happens in the Eluvial horizon?

A

where maximum leaching (or eluviation) takes place – the horizon that loses the minerals

51
Q

What is the illuvial horizon?

A
  • Lower horizon that gains the material - maximum accumulation happens
52
Q

What does white soil indicate?

A

quartz or salts

53
Q

What does red soil indicate

A

Iron oxide accumulation

54
Q

what does brown or black soil indicate

A

type and level of organic matter

55
Q

What colour will poorly drained gleys be

A

grey / blue-grey

56
Q

what does grey/ blue colour soil indicate?

A

Poor drainage with anaerobic conditions (no O2) - usually gleys

57
Q

What causes soil colouration?

A

oxidation - reduction

58
Q

What is the texture of loam soil?

A

A combination of sand, silt and clay

59
Q

Put in order of size: silt, sand, clay

A

Clay - smallest
Silt - intermediate
Sand - biggest

60
Q

Name 3 ways texture affects soil

A
  • Soils ability to hold water
  • Soils ability to hold and supply plant nutrients
  • Suitability for different plant species
  • Trafficability of the land, and the ability to support structures
  • Macro and micro fauna that live in the soil
61
Q

What are the 4 types of soil texture

A

Sand
Clay
Silt
Loam

ENVIRO & ECOLOGY (24 decks)

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