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EESC456 > EESC456-CHAPTER3 > Flashcards

EESC456-CHAPTER3 Flashcards

1
Q

What is meant by diagnostic horizon?

A
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2
Q

Compare CSSC (all soils in Canada) and USDA (soils on Earth) soil classification systems, to what extent they parallell each others + differ?

A
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3
Q

Pedon

A

The smallest unit that displays the full
range of properties characteristic of the soil type (scale of 1 to 10 sq.m)
–>”species”

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4
Q

Polypedon

A

group of similar pedons, collection of same soils (comparable to cluster of plants of same species
–>” community”

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5
Q

Soil series

A

class of soils, all with same diagnostic properties

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6
Q

Canadian System of Soil Classification (CSSC) horizons

A

Organic horizon: L, F, H (litter derived) or O (peats - wetland derived)
–> Different broken down levels: Litter, fermentation humus (=L,F,H)

Mineral horizons (<17% org. C (~<30% o.m. by mass)): A, B, C
–> diagnostic mineral soils

R – rock (too hard to dig with spade when moist)
–> included in soil profile in Canada

W – water or segregated ice layer in Cryosol

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7
Q

USDA soil hierarchical organisation

A

Series (1900), family (8000), subgroup (2500), great group(300), suborder (60), order (12)

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8
Q

CSSC soil hierarchical organisation

A

Series, family, subgroup, great group, order (10)

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9
Q

USDA diagnostic subsurface horizons

A

18 organised around origin, but distinguished by objective criteria

A. minimal accumulation (2)

B. accumulation (13)=
-silicate clays (4) - clay minerals
-organic matter (3)
-inorganic salts (5)
-sulfur (1)

C. pan development (3); hardening in soil profile

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10
Q

USDA diagnostic surface horizons (epipedons or A horizons)

A

Criteria: organic matter content, thickness,
colour, calcium & magnesium content

  1. Melanic: derived from volcanic materials
  2. Mollic: high base saturation
  3. Umbric: low base saturation
  4. Histic: formed in organic matter

**not core one: 5. Anthropic: man-made soils (mining)

  1. Ochric (thin + pale): low base saturation
    -used as “default” category
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11
Q

Soil classification/taxonomy/pedology is based on

A
  1. objectively observed or measured soil
    properties defining the diagnostic horizons (facts, can be assessed exactly)
    –>Criteria: colour-Munsell colour chart, texture, o.m., moisture status, temperature, % base saturation, clay content, Fe & Al oxides, pH, clay activity
  2. Unique nomenclature (e.g. American)

–>Classification depends on purpose, and population (Canada vs US vs Russia)

–>Different soil taxonomies use similar criteria but different terminology (nomenclature, naming conventions)

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12
Q

Hierarchical organization of soils, based on …

A

genesis (criteria that indicate the soils developmental history, to what extent soil is developed)

–>climatic genesis (soil temperature + dry/moist/wet)

–> Histosols + Organics are determined by local anaerobic conditions (not by climatic conditions)

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13
Q

Characteristic combinations of
(2)
give you the unique elements of the classification. So, the whole system depends on how you define …

A

Diagnostic surface horizon over
Diagnostic Subsurface horizon/s
+ sequence of soils

your diagnostic horizons

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14
Q

USDA Nomenclature

A

Logical, compact and informative; but foreign

–>Names strung together using root of full name. Root = soil order

–>Names grow to left – refined or specified by adding “adjectives” to root

Root is soil order (one of 12),
–>modified by prefix (qualifiers) to create Suborders (+1)
–>Many types of qualifiers, see Tables of formative elements for suborder and great groups (+2), subgroups (+3), family (+4), series (+5)

-Soil moisture regime soil formed under (aquic, udic, ustic, aridic, xeric)
-Soil temperature regime soil formed under (cryic, frigid, mesic, thermic)

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15
Q
  1. Entisols; (ent)
A

New soils (slightest weathering)
little/no horizon development
–> no B horizon, not enough soil development
–> little variance between C horizons
–> A horizon onto subsurface materials
Erosion
Aridity
Varied locations, all continents

–>CSSC = regolic

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16
Q
  1. Inceptisol (ept)
A

Mild weathering
various conditions
Young soils
No mature horizons, some diagnostic features
Weakly developed A (usually ochric)
Varied locations, all continents, poles»

–>CSSC = Brunisolic (brown soils)

17
Q
  1. Andisols (and)
A

**special parent material
Mild weathering on volcanic ejecta
Volcanic ash soils
Melanic A with high o.m. content
light, easily worked (plowed/tilled), little aggregations
Erodible in arid conditions

Coast of Americas

–>CSSC = not distinguisd

18
Q
  1. Gelisols (el)
A

Defined by climate
Slight weathering
Very cold, permafrost
Frozen soils
Little development because of low temperature
Permafrost (frozen for over 2 years, unlikely to thaw every year) within top 100 cm of soil profile
Typical frost churning = road damage, permafrost landscape
–> Ice wedges; highly wet materials frozen into wedge
Nothern hemisphere, Alaska, high in mountains, alpine areas, poles»

–> CSSC= Cryosolic

19
Q
  1. Histosols (ist)
A

Organic soils without permafrost
wetland soils
little profile development due to anaerobic conditions
–> no O2 = o.m. break down is stopped so it builds up

Deep accumulation of organic matter (thick layers-substantial depth of o.m., not just litter on top)
–>Dark to black/grey/brown
–>Very low density
–>high water-holding capacity
Weak; easily cultivated, easy to separate materials

Wet conditions
–>water = only limitation in that profile

Decomposes when aerated (worked or drained)
–> cultivating or draining soil = profile dries up (pores = air so o.m. breaks down), soil lowers down

High latitudes»
Everywhere wetlands (water saturation in profile that sits and prevents o.m. break down)

–> CSSC= Organic, then subdivided with extent of o.m. break down:(Fibrisols (Of), Mesisols (Om), Humisols (Oh))

–> significant area of Canadian peatlands

20
Q
  1. Aridisols (id)
A

Desert shrubs
Grasses, dry
largest global order, largest landmasses
>90 days soil moisture insufficiency (long dry period in year)

Light coloured (ochric) A horizon; not thick or dark enough

Unleached B horizon; too arid, not enough water to wash anything away = nutrient-rich BUT not productive (because no water)

Accumulation of carbonates, gypsum, soluble salts, exchangeable sodiums (= problematic)

Low soil development, lots of rocks
–> stone pavement = indicator of aridisols
–>petrocalcic horizon (harden layer, cemented with calcium carbonate)

soil of deserts, not widespread, most subtropical areas

–> CSSC = no equivalent, not important enough here
–> Canadian dry prairies; wind erosion risk, salt risk

21
Q
  1. Vertisols (ert)
A

*Soil (Swelling clays) = special feature
* High base status
* High activity clays
* Dry season
* Limited global distribution: drier, warmer climates & base rich parent materials (leached away, remain in soil), seasonal drought-well defined dry season

  • Strongly active clays, >30%, to 1 m depth
  • Dark colour, not necessarily derived from o.m.
  • Remarkable, notable features (cracks, gilgai, slickensides, self mulching)
  • Difficult to work/cultivate (sticky when wet (heavy, minerals stick together), strong when dry = rock)
    –>because of swell/shrink
    –> but highly fertile due to high clay content (base saturation)

–> CSSC = Vertisolic (>60% clay, at least half is smectite}
–> Localised distribution in Canada, must be identified because problematic = southern prairies, BC interior
–>* CSSC - argillopedoturbation

22
Q
  1. Mollisols (oll) **most important?
A

Soft, dark
* Accumulation of calcium-rich o.m. to form thick (>10 cm deep), dark, mollic / chernozemic
–> not highly leached environment

A-horizon, with high base exchange
capacity
* Breaks up in crumb structure but soft
* Cool, sub-arid to sub-humid plains of prairies
* Economically important; agriculture (productivity)
–> grassland soils in prairies
–> russia, ukraine

  • Semi-arid to moist
    –> little rain can cause calcium carbonates to accumulate at bottom of profile)
  • Grasslands, mollic epipedon (mollic = soft –> easily plowed)

–> CSSC = Chernozemic (Black Earth), some
Solonetzic soils
–> typical prairie landscape
–> climatic gradation???

23
Q
  1. Alfisols (alf)
A

Mildly acid clays
Moist, mildy acid
Clay accumulation

  • More weathered than mollisols, less so than
    spodosols (podzols)
  • Typically soils of deciduous forest or
    savanna, all continents
  • Defined by accumulation of clays: >35%
    base saturated (= mod. leaching)
  • Argillic, maybe natric or kandic
  • Typically have thin ochric A, & may have E

–> CSSC = Luvisolic, some Solonetzic

24
Q
  1. Spodosols (od)
A

Spodic horizon
Cool, wet, sandy
Acid coniferous forest
Allow bases
Nothern hemisphere

  • Intensive acid leaching, with spodic B (o.m. & Al (+Fe) accumulation)
    –> Bh, Bs
  • Spodosol usually underlies light, eluvial albic horizon
  • Coarse parent material, moist to wet climate
  • Acid vegt: forest (particularly conifer) or heath
  • Naturally infertile, but productive when fertilized
  • Risk of leaching of nutrients (fertilizers)
  • Risk of acid drainage
  • Extensive distribution in Canada (forests, E & W)

–> CSSC = Podzolic

25
Q
  1. Ultisols (ult)
A

Strongly acid clays
Wet, usually warm forests
Acid silicate
Fe, Al oxides
Argillic horizons with low bases
– low activity clays
* Weathered & translocated clay minerals,
and leached base status
* Typical of warm, humid conditions;
(sub)tropics/ecuator region
* Low bases (<35% saturation), acidic B’s
(kandic)
* More weathered & acidic than Alfisols, but
less so than Spodosols (podzols

–> no CSSC equivalent

26
Q
  1. Oxisols (ox)
A

oxides
Wet tropical forest
Extreme weathering
low activity clays
Fe, Al oxides

  • Deep oxic subsurface horizon
  • Soils of humid tropics & subtropics (old soils)
  • Clay breakdown, leaving non-swelling clays (1:1 clays); Fe & Al-oxides
  • Apedal soils (no structure), well drained, low fertility

–>CSSC no equivalent as it is not relevant in Canada (only southern hemisphere)

27
Q

Podzolization

A

The mobilization in, and removal from, an A
and/or E of o.m. and sesquioxides The darkened portion of the E has coarse sand-size grains. The illuvial horizon has increased Al & Fe-oxides and/or organic matter.

28
Q

CSSC, 3 Great Groups within Podzolic order:

A
  1. Humic Podzols – very wet conditions (aquic) = reducing env., hydrophytic vegt.
  2. Ferro-humic Podzols – high rainfall, not reducing
  3. Humo-ferric Podzols – less humid
29
Q

***Gleysolic Order:

A

Only recognized in Canada

Excess water (permanent or sustained reducing conditions due to landscape position, climate, texture)

Gley (group color) ; washed out grey/pale, can include pale blue, pale greeans, mottles (rust colours).

30
Q

***Solonetzic order:

A

Not singled out in USDA

  • Contains Solonetzic B (Bn or Bnt; strong structure (prismatic, columnar or secondary blocky); hard to ex. hard consistence when dry; ratio of Ca to Na is 10 or less.

-Soils of interior semi-arid to subhumid plains; grassland or forbs

-Parent materials uniformly salinized with high Na salts

-Usually have prismatic or columnar structure

-Free sodium problems

31
Q

Cryoturbation:

A

frost heaving of soil body
Cryo = frozen
Turbation = churning = Expansion when frozen, settles out when thawing
vertical + horizontal movement

=challenge to build structures on top of soil

=specled surface, evidence of churning in soils (creates blotches/patterns on surface)

32
Q

Argillopedoturbation

A

Argilo (clay)
Pedo (soil)
Turbation (turning)

Chruning of soil profile caused by shrinking and swelling of active clays

33
Q

Self mulching

A

surface material crumbling up; falls = mixing of soil

->cracks = defining features

34
Q

Slickenside

A

Aggregates in soil moving together = polishing. Clay skins forming in structural units in soil

35
Q

Gilgai

A

(microrelief) hollows/depressions forming on surface landscape, rolling topography

EESC456 (11 decks)

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