Earthworms are known as ‘farmer’s friends’. Why?

Solution:

Earthworms are called ‘farmer’s friends’ because they improve the texture and quality of soil. By burrowing into the soil, they make the soil loose, thus allowing air to pass through it and water to drain from it. It gets easier for soil to breathe. Earthworms also increase soil fertility by excreting the undigested materials into the soil.