Why is earthworm called nature's ploughman?

Explanation

**Step-by-Step Solution:**

1. **Introduction to Earthworms**: Earthworms are important organisms found in the soil. They play a crucial role in maintaining soil health and fertility.

2. **Soil Fertility**: Earthworms contribute to soil fertility by breaking down organic matter, such as dead leaves and plants. This process enriches the soil with nutrients that are essential for plant growth.

3. **Bringing Subsoil to the Surface**: Earthworms burrow through the soil, which allows them to bring mineral-rich subsoil to the surface. This action helps to enhance the nutrient content of the topsoil where plants grow.

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