Earthworms are extremely beneficial in agriculture. They aid in the following ways:
They help loosen up and aerate the soil as they burrow deep. This aids in the respiration of the roots of the plants, making them penetrate deeper and grow well
They are being used presently in vermiculture to produce high-quality manure
They are also used as baits to catch fish
They keep interchanging the topsoil with the layer just below, thereby increasing soil fertility.
The excreta of earthworms is rich in the nitrogenous matter and is required for plant growth