Question

Read the following statements with respect to soil profile and choose correct statements :
A. $OL_2$ layer is organic in ture in which plants and animals residue can be recognized visually.
B. $A_1$ layer is the uppermost mineral soil rich in organic matter.
C. $A_2$ layer is washing out zone.
D. $B_2$ layer is the zone of accumulation of clay and hydrous oxides.
E. $B_2$ layer generally lower in organic matter than that of $A_2$ layer.
Choose the correct answer from the options given below :

• A. A, B, C only
• B. B, C, D only
• C. C, D, E only
• D. A, C, D only

Hint:

Master Soil Horizons Code:
- $A_2$ E horizon = Eluviation (Washing OUT zone).
- $B_2$ B horizon = Illuviation (Accumulation IN zone).
Organic matter content decreases progressively down the profile ($A_1 > A_2 > B_2$).

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks to evaluate pedological statements describing master horizons and sub-horizons in a typical forest soil profile.

Step 2: Pedological Horizon Alysis:

• Organic Horizons ($O$): $OL_1$ ($Oi$) consists of fresh, undecomposed litter. $OL_2$ ($Oe$) is the fermentation layer where partial decomposition occurs.
• A Horizons: $A_1$ is the mineral horizon mixed with humified organic matter. $A_2$ (E horizon) is the eluviation zone ("washing out zone") from which clay, iron, and aluminum oxides are leached.
• B Horizons: $B_2$ is the illuviation zone ("accumulation zone") where leached silicate clays, iron, and aluminum hydrous oxides deposit.
• Organic Distribution: Organic carbon concentration decreases strictly with profile depth ($A_1 > A_2 > B_2$), making $B_2$ lower in organic matter than $A_2$.

Step 3: Detailed Statement Verification:

• Statement C is correct: $A_2$ horizon is the eluvial/washing out layer.
• Statement D is correct: $B_2$ horizon is the illuvial/accumulation layer for clays and oxides.
• Statement E is correct: $B_2$ subsoil contains less organic carbon than the overlying $A_2$ horizon.
• Statements C, D, and E form the valid combition under standard soil profile desigtion options.

Step 4: Fil Answer:
The correct statements are C, D, E only. Thus, option (C) is correct.