Practice exam #3 - QUESTION 6

a) Goose soil belongs to Gleysolic Order. The diagnostic horizon is Bg.

b)advantages: because silt and clay accounted for the large proportion of soil texture, Goose soil would have high water retention. Then organic matter would form soil aggregates to retain nutrients. High CEC which give the soil high buffering capacity, if there is acid rain the soil would not much affect. Soil pH is neutral.

disadvantages: soil contains small percentages of sand and high percentages of clay would cause low infiltration, poor drained.

I am not sure about how does Ca, Mg, K, Na influence plants grow. They provide nutrients, but high Ca would cause phosphorus deficiency in soil. While, high Ca exchangeable cations can exchange more nutrient? Also, if the roots are abundant in A horizon does it means the soil has a low decomposition rate? I checked the note of soil structure where can i find more details.

Yiming, consider how soil properties, such as texture and structure change with depth (as well as root abundance).
With respect to P fixation, consider pH (not just Ca).
Ca, Mg, K are all essential plant nutrients. Na is only an issue if levels are high (i.e., sodic soil)
High root abundance does not suggest slow decomposition, but good plant growing conditions.