Question

Given below are two statements
Statement I: The epipedon which is light in colour and contains $<$1% organic matter is known as Ochric epipedon
Statement II: Dark coloured epipedon having $>$50% base saturation and organic matter of $>$1% is known as Histic epipedon
In light of the above statements, choose the correct answer from the options given below

• A. Both Statement I and Statement II are true
• B. Both Statement I and Statement II are false
• C. Statement I is true but Statement II is false
• D. Statement I is false but Statement II is true

Hint:

Ochric = "Ordinary" (the default, light surface).
Mollic = "Mellow" (dark, rich, and alkaline).
Histic = "Histology" (tissue/organic). If it's Histic, it must be very high in organic matter, not just $>1\%$.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks to verify the definitions of diagnostic surface horizons (epipedons) used in Soil Taxonomy.
Detailed Explanation:

• Evaluating Statement I:
The Ochric epipedon is a default diagnostic surface horizon. It is characterized by being too light in color, too thin, or too low in organic matter (typically $<1\%$) to be classified as Mollic or Umbric. Therefore, Statement I is True.

• Evaluating Statement II:
The description provided in the statement ("Dark colored, $>50\%$ base saturation, $>1\%$ OM") actually describes a Mollic epipedon, which is the characteristic horizon of fertile grassland soils (Mollisols).
A Histic epipedon, on the other hand, is a surface horizon that is saturated with water for part of the year and contains a very high amount of organic matter ($20\%$ to $30\%$ or more, depending on clay content). It is basically an organic layer over mineral soil.
Therefore, Statement II is False.

• Summary of Epipedons:
Mollic: Dark, thick, high base saturation ($>50\%$).
Umbric: Dark, thick, low base saturation ($<50\%$).
Ochric: Light, thin, or low organic matter.
Histic/Melanic: Very high organic matter or volcanic influence.

Step 2: Final Answer:
Statement I is correct as per standard soil taxonomy definitions, but Statement II incorrectly defines the Histic epipedon.