Question

Comparatively stable fraction of the soil organic matter, left after the decomposition of major portion of added plant and animal residues, is called

• A. Podzol
• B. Mineralization
• C. Humus
• D. Immobilization

Hint:

Humus:
- Stable fraction of soil organic matter.
- Improves soil fertility and structure.
- Resistant to further decomposition.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
This question tests knowledge of soil organic matter decomposition.

Step 2: Detailed Explanation:
Humus (C) is the comparatively stable fraction of soil organic matter.
It remains after the decomposition of the major portion of added plant and animal residues.
Humus is dark, amorphous, and rich in carbon.
It improves soil structure, water holding capacity, and nutrient retention.
Other terms:
- Podzol (A): A soil type (not organic matter).
- Mineralization (B): Conversion of organic to inorganic nutrients.
- Immobilization (D): Conversion of inorganic to organic nutrients.
Thus, humus is the stable fraction of soil organic matter.

Step 3: Final Answer:
Thus, the stable fraction of soil organic matter is called humus, which corresponds to option (C).
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