Practice exam #3 - QUESTION 5
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.