Economic Importance of Earthworm!
Useful Affairs of Earthworms:
The earthworms are better known as the friend of farmers due to the following reasons:
1. The earthworms improve the fertility of soil in different ways and, therefore, they are of utmost importance in agriculture. Actually, the burrowing and soil feeding habits of earthworms make the soil porous which permit both aeration and quick absorption of water. It also permits easy and deep penetration of the plant roots.
They also bring the fresh subsoil to the surface which is still finer and rich in organic matters. Charles Darwin has estimated that an acre of earth is inhabited by nearly 50,000 earthworms (a recent estimate suggests that their number may reach up to 25, 00,000 per acre) which may bring more than 18 tons of deeper subsoil to the surface in one year.
This may in 20 years form a layer of 7.5 cm thick surface on the earth in the form of their castings. The castings of earthworm contain fine soil having mixed with its nitrogenous wastes and faeces of nice manurial value. The faeces of earthworm contain nitrate, calcium, magnesium, potassium and phosphorus which constitute an important component of the humus essential for plant growth.
They also reduce the alkalinity and acidity of the soil to provide better conditions for plant growth. After their death and decomposition, they increase the organic constituents of the soil. Thus, the earthworms make the soil fertile to a great extent. Thus, these worms are also known as natural ploughmen or tillers of the soil.
2. These are used as bait and food. As bait they are used in fishing. The earthworms were used as food by so many uncivilized people of the world and they are still used as food by Macrea people. The earthworms are eaten upon by frogs, toads, moles, hedgehogs and birds which are of many uses to mankind.
3. Many people earn their livelihood by catching these worms and supplying to scientific laboratories.
4. Ayurvedic and Unani system of therapy suggests that these worms were used in making medicines for the cure of diseases like bladder stones, jaundice, pyorrhoea, piles, rheumatism, etc. Even today, these are used in making various medicines of vital importance in India as well as other countries.
Harmful Affairs of Earthworms:
They may damage young and tender plants by eating them bit by bit. They also damage the grass lands by making tunnels in the ground when present in huge numbers. They are also said to help soil erosion. Some earthworms act as secondary hosts for the completion of life stages of some parasites which are directly or indirectly harmful to mankind.