Soil Orders and Parent Material — Sandy Parent Materials Soils that commonly develop where the parent material tends to be rich in sand are typically classified as which soil order (USDA system, conceptually)?

Introduction / Context:
This pedology question links soil orders to their typical parent materials and forming environments. Spodosols (often misspelled as “spodsols”) commonly develop in sandy, acidic parent materials under coniferous or heath vegetation, especially in cool, humid climates where leaching is strong.

Given Data / Assumptions:

• Parent material has high sand content (coarse texture, low buffering capacity).
• Cool to temperate humid climate favors leaching.
• Organic acids from vegetation promote horizon differentiation.

Concept / Approach:
Spodosols are characterized by an eluviated E horizon and an accumulation of organic matter, aluminum, and iron in a spodic B horizon. Sandy textures facilitate leaching and translocation of these complexes. Other soil orders listed (Alfisols, Aridisols, Ultisols) can occur on varied textures, but their diagnostic features and climatic associations differ from the classic sandy, acidic spodosol setting.

Step-by-Step Solution:

Verification / Alternative check:
Introductory soil science texts depict spodosol catenae on glacial outwash sands and coastal sands under pine forests; profiles show bleached E horizons and dark spodic accumulations.

Why Other Options Are Wrong:

• Alfisols: Moderately leached, often finer textures; argillic horizons under deciduous forests/grasslands.
• Aridisols: Dryland soils; sandy variants exist but the key control is aridity, not sand-rich parent alone.
• Ultisols: Strongly leached, older soils with clay-enriched Bt horizons; not typically tied to very sandy parent material.

Common Pitfalls:
Assuming any sandy soil must be an Aridisol; climate and diagnostic horizons matter, not just texture.

Final Answer:
spodsols