Practice exam #3 - QUESTION 5

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Question 5: a) Cy- y denotes cryoturbation

Of- From a poorly drained forest soil, the f denoting “fibric” or containing organic material that is largely discernable/undecomposed.

Cg- g denotes gleying, ie periodic intervals of intensely anaerobic conditions and not. With this, we tend to see mottles or orange/red from oxidation

LFH- Forest floor, the site of plenty of organismal activity, biomass additions, and decomposition

Bfgj- Likely a podzolic soil, as denoted by the f in Bfgj, f indicating the accumulation of iron in the horizon. With that, we have a younger gleyed horizon.

b) Cy- In uppermost latitudes, very cold climate where most of soil profile will be frozen (added by Maja)
Of- in a poorly drained forest ... not forest, but bogs and/or wetlands or any other sites with poor drainage (Maja)
Cg- in most areas where you would find the water table close to the surface you might expect to find this kind of horizon.
LFH- In well drained forest soils
Bfgj- In a forest with predominantly coniferous vegetation, say Pacific Spirit Park, or a lower-Boreal forest in BC/QC

c) Example 1: Diagnostic Horizon: Bv/Bss Order: Vertisolic

Example 2: Diagnostic Horizon:Of and W, with W denoting a layer of water which makes perfect sense as OF is used for poorly drained soils Order: Organic

Example 3: Diagnostic Horizon: Bt horizon overlayed by an Ae Order: Luvisolic (Bf layer too thin to be a Podzol)

Example 4: Diagnostic Horizon: Very thick Ah and 1-17% organic C, with Ca2+ dominant cation Order: Chernozemic

             Example 5: Diagnostic Horizon: Bm
             Order: Brunisolic

Jacob, note that lower case "j" can denote juvenille OR weakly developed, thus in the Btgj the gleying is weakly expressed

QUESTION 5:

a) Soil horizons are described by either just upper case letters OR a combination of upper and lower case letters, where lower case letters indicate the specific soil forming process occurring in that horizon. For each of the following soil horizons, identify the soil forming process(es):

Cy: A C horizon affected by cryoturbation (frost action)

Of: Organic/fibric horizon. Consists dominantly of well-preserved fibers that are readily identifiable. (Low decomposition)

Cg: A gleyed C horizon, has grayish color and or mottles.

LFH: Organic horizons referred to as a forest floor. L horizon accumulation of fres undecomposed organic matter where decomposition is low and plant additions are still identifiable. F horizon is accumulation of partially decomposed organic residues. H horizon will have very well decomposed organic matter where the original organic structures are no longer identifiable. This material is different from the F horizon due to the action of organisms and is intermixed with mineral grains.

Bfgj: A juvenile B horizon that is affected by the enrichment of Fe/Al oxides and is also a gleyed horizon, gray in color as a result or permanent or periodic anaerobic conditions, containing mottles possibly.

b) Briefly comment under what environmental conditions (e.g., climate, vegetation, drainage, type of parent material) would you expect to find each of these horizons.

Cy: In a cryosolic order in the C horizon, possibly in Northern Canada where permafrost occurs and causes strong cryoturbation.

Of: At the surface of an organic order soil, more than likely in a poorly drained area, where there is >17% organic carbon or >30% organic matter by weight.

Cg: Located in an area where permanent or periodic anaerobic conditions occur. Could exist in a gleysolic order soil. Poorly drained mineral soils. Could exist in depression or on flat plains where water accumulates.

LFH: At a relatively well-drained forest floor.

Bfgj: A newer area (hence a juvenile soil) where there is an area where there is permanent or periodic anaerobic conditions, and has iron and aluminum oxides. Could exist in an area where ever surface water accumulates once and awhile.

c) With reference to the Canadian System of Soil Classification, identify the most likely soil order represented by each of the following 5 examples shown below.

Example #1: Vertisolic Order. Has both the presence of vertic and slickenside horizons within 1m on the surface. → Diagnostic Horizons: Bv, Bss, and Css.

Example #2: Presence of an organic horizon at least 40cm thick (60cm in the case of Of). Therefore an organic order, with a diagnostic Of horizon.

Example #3: Luvisolic order. There is a presence of a Bt horizon at least 5cm thick (diagnostic horizon). Also in a mixed forest under cold and humid climate.

Example #4: Chernozemic Order. (0-28cm thick Chernozemic Ah horizon which meets all the correct requirements to be a chernozemic Ah horizon). Also located in a grassland semi-arid climate with good natural drainage. - Chernozemic Ah (diagnostic horizon).

Example #5: Brunisolic Order. A Bm horizon is present at least 5cm thick (diagnostic horizon). Also in a deciduous forest under a cold/humid climate.

Mirleigh, be careful with lower case "j" - it applies to the letter it follows only, thus in Btgj it is the gleying that is weakly developed.

a) Cy: cryoturbation (translocation)

   Of: Addition of organic residues
   Cg: Gleying, which is reduction mostly and oxidation at mottles (transformations)
   LFH: Addition of organic residues and breakdown of organic residues into humic substances (transformations).
  Bfgj: Illuviation with Fe/Al oxides (strongest; translocation) and gleying, which consists of reduction in most places but oxidation at mottles (transformations)

b) Cy: Mean annual soil temperature should be less than 0 degrees Celsius. I would expect this layer in a tundra.

   Of: I would expect to find this horizon in a poorly drained area with a high water table year-round. Generally, a marsh, bog, or some kind of wetland. 
  Cg: I would expect to find this horizon in a location with poorly drainage that has a high water table for portions of the year. These landscapes would generally also be some kind of wetland probably and could have a dense parent material like basal till. 
  LFH: You would tend to find this horizon in forest ecosystems, or really any well-drained natural ecosystem should have some amount of litter on the surface in various states of decomposition, which would be an LFH horizon.
  Bfgj: You would find this kind of horizon in a somewhat poorly drained coniferous forest. 

c) #1: Vertisolic order. Diagnostic horizons: Bv, Bss, Css

   #2:  Organic order. Diagnostic horizon: Of
   #3:  Luvisolic order. Diagnostic horizon: thick Bt
   #4: Chernozemic order. Diagnostic horizon: chernozemic A
   #5: Brunisolic order. Diagnostic horizon: Bm

a) Cy: horizon affected by cryoturbation

Of: fibric horizon

Cg: gleyed horizon, under intense anaerobic conditions

LFH: organic horizons basic on the accumulation of leaves, twigs, roots

Bfgj: the horizon has abundant Fe and Al which shows gray color because of anaerobic conditions but this layer is thin, slightly noticeable.

b) Cy: soil temperature remains below 0 degree

Of: poorly drained area (saturated)

Cg: anaerobic condition

LFH: well-drained area, in forest

Bfgj: coniferous forests

c) 1: Vertisolic Order (Bv,Bss,Css)

2: Organic Order (of)

3: Luvisolic Order (Bt)

4: Chernozemic Order (Ah)

5: Bruisolic Order (Bm)