Which of the following is not a characteristic feature of the humus?

Options

A. It is a dark coloured, amorphous substance
B. Highly resistant to microbial action
C. It is reservoir of nutrients
D. Cannot be degraded further

Answer

To determine which of the following is not a characteristic feature of humus, we will analyze each option provided.

1. **Dark colored amorphous substance**:
- Humus is indeed a dark-colored, amorphous substance. It is formed from the decomposition of organic matter and is a key component of soil. Therefore, this option is a characteristic feature of humus.

2. **Highly resistant to microbial action**:
- Humus is known for its resistance to microbial action, which means it does not decompose easily. This property allows humus to persist in the soil and contribute to its structure and fertility over time. Thus, this option is also a characteristic feature of humus.

3. **Reservoir of nutrients**:
- Humus acts as a reservoir of nutrients, providing essential elements for plant growth. It contains a variety of nutrients that are slowly released into the soil, making it beneficial for plants. Therefore, this option is a characteristic feature of humus as well.

4. **Cannot be degraded further**:
- This statement is not true for humus. While humus is more resistant to degradation than fresh organic matter, it can still be broken down by certain microorganisms and processes over time. Therefore, this option is the one that is not a characteristic feature of humus.

**Conclusion**: The correct answer is that "cannot be degraded further" is not a characteristic feature of humus.