Question

Release of iron from primary minerals and their dispersal as coatings on soil particles to impart brown to red colour to soil particles
(A). Braunification
(B). Ferruginisation
(C). Rubification
(D). Laterisation
Choose the correct answer from the options given below:

• A. (A), (B) and (D) only.
• B. (B), (C) and (D) only.
• C. (A), (B) and (C) only.
• D. (A), (C) and (D) only.

Hint:

Iron oxides are the primary coloring agents in soils:
- Goethite ($\text{FeOOH}$) $\rightarrow$ Yellowish-brown (Braunification).
- Hematite ($\text{Fe}_2\text{O}_3$) $\rightarrow$ Red (Rubification).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Pedogenic weathering processes release iron from primary minerals. The hydration, dehydration, and dispersion of these iron oxides on soil particle surfaces develop distinct soil colors.

Step 2: Detailed Explanation:
Let us evaluate each process related to soil color development:
- Braunification (A): The release of iron from primary minerals and its conversion into hydrated iron oxides (like goethite), which coat soil particles and develop a brown color.
- Ferruginisation (B): The accumulation and coating of soil mineral surfaces with iron oxide precipitates, often under alternating wet and dry conditions.
- Rubification (C): The development of a bright red color in soils under warm, dry seasons as hydrated iron oxides dehydrate into hematite ($\text{Fe}_2\text{O}_3$).
- Laterisation (D): A broader, landscape-level soil-forming process (desilication) rather than a specific term for iron mineral color coatings.
Therefore, the specific sub-processes responsible for iron coating and coloring of soil particles are (A), (B), and (C).

Step 3: Final Answer:
The correct option is (C).