Question

Difficulty: MediumSoil Formation, Profiles, and Major Vegetation Types

Match each soil horizon process or zonal pedogenic process on the left with its corresponding characteristic soil profile feature on the right.

  • EluviationLoss of soluble minerals and colloidal particles from Horizon A by percolating water
  • IlluviationAccumulation of washed-down clay, iron, and aluminum compounds in Horizon B
  • LateritizationFormation of a red, iron-rich sesquioxide soil layer due to silica removal in hot, humid climates
  • PodzolizationDevelopment of a heavily bleached, ash-grey subsurface horizon under acidic coniferous forest litter

Answer

Eluviation pairs with the loss of soluble minerals and colloidal particles from Horizon A by percolating water; Illuviation pairs with the accumulation of washed-down clay, iron, and aluminum compounds in Horizon B; Lateritization pairs with the formation of a red, iron-rich sesquioxide soil layer due to silica removal in hot, humid climates; Podzolization pairs with the development of a heavily bleached, ash-grey subsurface horizon under acidic coniferous forest litter.
Each pedogenic term accurately aligns with its diagnostic profile feature: Eluviation describes removal of minerals from topsoil, Illuviation describes their accumulation in subsoil, Lateritization describes silica-leached tropical soils rich in iron, and Podzolization describes acid-leached boreal soils with an ash-grey layer.

Step-by-Step Solution

1
Distinguish between horizon-level transport mechanisms: eluviation vs. illuviation.
Eluviation represents the exit/removal of minerals from Horizon A/E, while illuviation represents the inward accumulation of those materials into Horizon B.
Understanding upper-to-lower profile movement is fundamental to soil horizon analysis.
2
Correlate broad regional climates with specific zonal pedogenic processes.
Lateritization is driven by high rainfall and temperatures in tropical regions (silica leaching), whereas podzolization is driven by cool, wet climates and acid litter (ash-grey Horizon E).
Climatic controls dictate chemical weathering pathways and soil profile characteristics across global biomes.

Key Concept

Soil Profile Horizon Processes and Pedogenic Weathering Types
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