Soils 3

Front 1

Levels in US Classification System

Back 1

Order, suborder, great group, sub group, family, series

Front 2

List several diagnostic horizons

Back 2

Spodic, argillic, oxic, mollic, histic

Front 3

Spodic diagnostic horizon

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B horizon with illuvial accumulation of Fe+3, Al+3 and humas. Bhs or Bs.

Front 4

Oxic diagnostic horizons

Back 4

Laterization of everything except Fe+3 and Al+3 weathered away.

Front 5

An argillic diagnostic horizon

Back 5

Bt horizon

Front 6

Twelve soil orders

Back 6

Alfisols, Andisols, Aridisols, Entisols, Gelisols, Histosols, Inceptisols, Mollisols, Oxisols, Spodosols, Ultisols, Vertisols.

Front 7

Two soil orders for young soils

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Entisols - young, weakly developed, with no B.

Inceptisols - relatively young, more developed than Entisols, might have B.

Front 8

Typical profiles in an Entisol,

Back 8

O,A,C
O,C
A,C
C

Front 9

Places where Entisols are typically found.

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Ridge tops, recent deposits, beaches, ash, and urban areas.

Front 10

Gelisols

Back 10

Soils with permafrost or cryoturbation. Cold or frozen most of the year. Organic or inorganic.

Front 11

Soils developed from volcanic material

Back 11

Andisols

Front 12

Characteristics of Andisols

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Developed from volcanic material. A Horizons that are rich in Al-humic materials. Secondary minerals are predominately amporphous. Range from moderate to well developed.

Front 13

Aridisols

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Dry soils, arid to semi arid. A Horizons with less plant growth. Can have many types of B Horizons, but Bks are common.

Front 14

Mollisols
List profiles.

Back 14

"Soft." Have a mollic A horizon. Greater than 50% base saturation with good physical properties. Usually under grasslands. Very fertile.
A B_ C, AC or A E B_ C

Front 15

Alfisols
List profiles

Back 15

Has a Bt Horizon. Moderate base saturation (35-50%). Lower fertility than Mollisols but still excellent soil. Common under deciduous forests and grasslands.
A E Bt1 Bt2 C, or A Bt1 Bt2 BC

Front 16

Ultisols
List Profiles

Back 16

Old, highly-weathered, acidic soil. Low base saturation (less than 35%). Has a Bt horizon. Lower fertilitiy than Alfisols. Common under forests. Developed in wetter temperate areas or tropical areas with lots of leaching. Easily degraded.

O A Bt1 Bt2 Bt3 C

Front 17

Orders that are likely to have Bt Horizon

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Alfisols, Ultisols

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Oxisols

Back 18

Most highly weathered, old soils. Lateralization with an oxic B horizon. Kaolinite common. A horizon low in organic matter. Common in tropic areas with high rainfall and a stable landscape

Front 19

Soil orders likely to be found in tropic areas

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Oxisols(stable environment), Ultisols (where heavy leaching)

Front 20

Soil orders likely to be found under grasslands

Back 20

Mollisols, Alfisols.

Front 21

Horizons with accumulation of Al-humic matter. What's the difference?

Back 21

Andisols, Spodisols. Andisols have accumulation in A horizon. Spodisols have illuvial accumulation in B horizon (Bs or Bhs)

Front 22

Spodosols

Back 22

Has a spodic horizon (Bs or Bhs) with illuvial accumulations of Fe, Al, O.M.) Usually has an E horizon. Acidic lower in fertility. Found in cooler temperatures, coniferous regions, areas with high leaching, course textured soil. O E Bhs Bs C

Front 23

Orders that are likely in forests and temperate regions.

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Spodisols - coniferous
Ultisols - old and leached
Alfisols - deciduous

Front 24

Vertisols

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High content of shrink swell clay in the upper 7 m of soil. Soil expands and contracts and mixes. Cracks open. Sub humid to semi-arid areas. Deep A horizon.

Front 25

Orders in arid, semi arid areas

Back 25

Aridisols
Vertisols

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Histosols

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Organic soils (little to no mineral material). Found in water logged areas of any type of climate. Wetlands. When drained, can be very fertile but difficult to manage due to poor properties. Oa Oe Oi

Front 27

Mollic diagnostic horizon

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Thick, dark colored, high base saturation, good structure, very fertile A horizon

Front 28

"Base" Cations

Back 28

Na, Ca, K, Mg

Front 29

Formula for base saturation

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Quantity of Base Cations/Cation Exchange Capacity

Front 30

What is a good base saturation for high fertility?

Back 30

50%

Front 31

The three soils orders defined by base saturation and the base saturation %s

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Mollisols - greater than 50%
Alfisols - 50-35%
Ultisols - less than 35%

Front 32

Explain how pH influences base saturation. Why?

Back 32

A low pH (acidic) leads to low base saturation. Higher pH (more basic) leads to higher base saturation.
When OH increases it pulls H+ off exchange cites and frees sites up for base cations.

Front 33

Podzolization

Back 33

The process by which soils are depleted of bases and become acidic.

Front 34

Define and explain laterization

Back 34

Intense weathering,high leaching, formation of oxides, rapid decomposition, deep soil. Occurs in high temp high prec good drainage with stable landscape. Remaining soil has lots of oxides, no silica, and is low in nutrients - Bo horizon.

Front 35

Four processes of soil formation

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Additions (water, OM, stuff from air)
Losses (bottom - water, colloidal minerals, nutrients; top - water, erosion, energy, gases)
Translocations (iron, OM.. from one horizon to the next)
Transformation (creation of new minerals from decomposition, weathering)

Front 36

Define and explain gleization

Back 36

Occurs in water logged, poorly drained soils. Causes mottles of orange and grey creating either a Bg or Cg horizon.

Results from the reduction of iron (addition of electron) from decomposing organic matter. Occurs when no O2 present. Normally O2 would take up the electrons. Can be mottled because of cycles of wetting/anerobic conditions.

Front 37

Explain and define podzolization

Back 37

Formation of Bhs or Bs horizons (Spodic soils) in temperate, cooler, high rainfall locations with coniferous vegetation and course textured soils.

Slow decomposing O horizon releases organic acids which grab onto and leach Fe and Al oxides out of A and E horizons and precipitate them into B horizon as they finish decomposing.