Pheretima posthuma is highly useful as

Options

A. their buffows make the soil loose
B. they make the soil porous, leave their castings and take organic debris in the soil
C. they are used as fish meal
D. they kill the birds due to biomagnification of chlorinated hydrocarbons

Explanation

**Step-by-Step Solution:**

1. **Identify the Organism**: The question refers to *Pheretima posthuma*, which is a species of earthworm commonly found in soil.

2. **Understand the Role of Earthworms**: Earthworms, including *Pheretima posthuma*, are often referred to as "friends of farmers" due to their beneficial activities in the soil.

3. **Soil Aeration**: One of the primary benefits of earthworms is that they create burrows in the soil. These burrows help to aerate the soil, making it loose and porous. This is crucial for plant root respiration and growth.

4. **Soil Fertility**: Earthworms contribute to soil fertility through a process called vermicomposting. They consume organic debris (like dead leaves and other plant material) and break it down, which enriches the soil with nutrients.

5. **Casting Production**: As earthworms digest organic matter, they excrete waste known as castings. These castings are rich in nutrients and further enhance soil fertility.

6. **Conclusion**: Based on the above points, *Pheretima posthuma* is highly useful as it makes the soil loose, porous, and fertile, and it contributes to the process of vermicomposting.

**Final Answer**: *Pheretima posthuma* is highly useful as it makes the soil loose and porous, increases soil fertility through vermicomposting, and leaves nutrient-rich castings in the soil.

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