If you want to know if your soil is healthy, dig up a clump of it and see if it has any worms in it. Chances are you may find one or two, but the more worms you find, the better. While there are hundreds of different types of worms, earthworms are the species that offer the most garden benefits. The earthworm is a long, slender, pinkish-blue worm that can be up to 6 inches in length. You may find them creepy, but if they weren't in your garden, your crops would suffer since they provide many benefits.
A group of young students in Cornell University's summer science camp observed the benefits of worms in garden soil first hand. When comparing good soil to poor soil, the students found that the good soil contained almost seven times more worms. One of the benefits to the soil that the earthworms provide is aeration. Aeration is a process in which the soil is broken up so that air, water and plant roots can move freely through the dirt. Loose soil also allows the plants to more readily absorb nutrients. The ability for roots to grow and for water to get to the roots is vital to plant health, and worms in the garden make sure the soil is not compacted.
Another benefit that worms provide is composting. Cornell educators explain that worms eat garden debris, such as dead leaves and dead plant matter. When they digest these items, they excrete it out as compost, which is loaded with nutrients needed in good soil. The "Wildlife Gardener" also notes that worm excrement, sometimes referred to as castings, wards off plant pests and diseases.
Birds: Good and Bad
Worms are part of the food chain and can attract birds to your garden. This can be a double-edged sword. The good part is that birds will feed on garden pests such as beetles, flies and mites. The bad news is that some birds, such as the American robin, will also feed on worms, which will decrease the number of worms that are hard at work tending your garden soil.