Earthworms: who are they? How important is the quality of a soil?


Her long body and viscous does not make it a graceful animal. What does it matter! The earthworm possesses many other qualities which elevate it to the rank of the most useful in the world. By promoting soil aeration and recycling organic matter, earthworms are among the gardener’s best friends.

Presentation of the earthworm

Earthworms belong to the order of Haplotaxida and to the suborder of Lumbricina. If their length varies according to the regions of the world, all are ringed and covered with fur that help them move around. Each end is punctuated by a ring: the thinnest forms the head, the larger the anus and the middle one (clitellum) contains the reproductive organs. Theinvertebrate has no teeth, eyes, ears and lungs but has three pairs of kidneys and five pairs of hearts! His slimy skin coats a mucus that constantly hydrates him. In period of drought, the earthworm can curl up on itself and cause lethargy which will minimize its biological activity while waiting for the soil to moisten.

Three major groups of earthworms

There are more than 5,000 species in the world and 150 in France, the most common of which are the common earthworm (Lumbricus terrestris) and manure worm (Eisenia fetida). According to level from the ground they frequent, we can distinguish three large groups of earthworms:

  • Worms overhead – also called manure worms – exert an action in area by consuming organic matter and plant debris (especially dead leaf residues). These red decomposers measure 5 cm maximum;
  • Worms endogenous dig long galleries horizontal and hardly ever come to the surface. They feed on soil mixed with organic matter present in the mineral part of the soil. Medium in size (up to 20 cm long), they are whitish pink in color;
  • Worms anecic are part of the megafauna by displaying a size large to giant (from 10 cm to 1 meter long). Their color varies from red-brown to gray-black at the head. These plowmen dig deep galleries vertical and rise to the surface to refuel organic matter.

Reproduction of earthworms

Reproduction of the earthworm can begin as soon as the clitellum, a swollen ring located in the middle of his body. All species are hermaphrodites, that is, they carry both male and female reproductive organs. Earthworms must nevertheless mate to fertilize. Before mating, the clitellum secretes a substance sticky that helps the two individuals to attach themselves upside down. Then the female expels eggs surrounded by a cocoon into mucus that the male fertilizes by ejecting sperm. About three weeks later, each cocoon releases between one and four small worms which will often reach their maturity sexual around three months and may in turn reproduce.

Role and usefulness of the earthworm for the soil

Earthworms release excrement called castings. These earthen twists are enriched with nutrients (nitrogen, phosphorus, potassium) as well as bacteria which play an essential role in plant nutrition. On the other hand, by digging its underground galleries, the earthworm participates in aeration and drainage of the ground. In addition, its consumption of plant debris and organic matter allows recycling of fermentable waste. In summary, earthworms promote in particular:

  • Soil stabilization;
  • Theinfiltration water while avoiding runoff phenomena;
  • Aeration of the earth;
  • The contribution nutrient to plants;
  • The recycling organic matter;
  • The development of the root system of plants;
  • Reduction of organisms or fungi harmful in the ground.

Preserve and attract earthworms to the garden

To contribute to the preservation of earthworms in the garden, it is strongly not recommended from:

  • Use a tiller, a tiller or a spade that destroy worms. Instead, use a grelinette which will aerate the soil without disturbing earthworms and other micro-organisms;
  • Use products chemical which are poisonous to many species including worms;
  • Tamp the soil with heavy objects or by trampling for this action suffocates the earth and reduces the population of worms;

Secondly, you can attract earthworms in your garden by taking care of:

  • Work the land preferably when it is dried for the earthworms take refuge in the lower layers;
  • Cover the soil with organic matter such as mulching, compost or manure;
  • Diversify crops and organic matter inputs in your vegetable garden in order to provide them with food rich and varied.

There are about 200 earthworms in square meter under a depth of two to four meters. In addition to being virtuous for the soil, earthworms participate in the balance of the ecosystem and in particular of birds of which they constitute an important part of the food.

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