The earthworm, the gardener's assistant
The common earthworm (a member of the ringed worm family, the Lumbricidae) is a hard worker and plays an essential part in the biology of the soil.
It digs tunnels in the soil which help in its ventilation and drainage. Theses tunnels facilitate the rooting and watering of our plants.
The earthworm blends the soil by constantly moving up and down, going as far as two meters deep. It transforms and brings elements like dead vegetation from the top of the soil to the bottom. It also brings trace elements like iron, sulphur, etc. from the sub-soil to the surface. It doesn't harm roots or plants.
Try the following experiment (your kids will love it): Place a layer of earth, evenly spread, in an aquarium, followed by a layer of sand, one of earth, one of sand, and so on until you reach half way up the aquarium. Put some dead leaves on the surface along with a dozen worms. After a month you will notice that the layers are no longer horizontal and that the soil is riddled with tunnels, most of which are concentrated in the layer of earth.
Its digestive system is a concentration of bacterian fauna which enriches and gathers together the soil's elements. The spiral which we see on the soil's surface is the result of its digestion. It displaces its own weight every day and helps neutralize the soil.
Finally, it helps spread the micro-organisms by digesting them and regurgitating them elsewhere.
These little creatures, often disliked, should therefore be preserved, as they are indispensible allies of a good gardener. In fact they are a good indicator of rich soil.
When you turn your soil over, do so with a fork rather than a spade, which tends to chop up our little friends.