top of page
Search

The Impact of Earthworms

Writer's picture: Christina BrandtnerChristina Brandtner

Earthworms have many fans. Quite some years ago when I was a child we visited a family friend in the same village where we lived. He was really an expert in terms of alternative gardening. I remember us going through his garden and marveling at all the ingenious systems and ideas he has put into practice. While we were talking and exploring two or three chickens of his parents entered his vegetable garden through the open door. Our dear friend was having a wheelbarrow in his hands and as soon as he saw the animals, he was running after them and shouted: "They are eating all my earthworms!". And these chickens were stressed and couldn't straight find the way out… Years later, we still laugh at this picture – the scolding wheelbarrow race after the chickens for saving earthworms…



The Life of Earthworms


In Europe we have around 400 species of earthworms – here in Austria are living only 60 of them and in our garden soil there are not more than 12 species. They dwell in different habitats and impact their ecosystems in very different ways.

Earthworms prefer medium-heavy loam to loamy sand soils. In heavy clay and dry sandy soil is their spreading limited. Besides some specialized species, they avoid acidic peat soils… Having no teeth, earthworms swallow predominant soil together with the containing microorganisms and organic matter. And they are feeding a lot – some say that one earthworm can eat up half of its body weight in only one day, some others say even 10 times its weight!


They are living three to eight years and are mostly active during the night. Because earthworms cannot regulate the body temperature themselves, they have to retreat in the wintertime to frost-free portions of their burrows, and their metabolism slows down to the minimum. The earthworm is also intolerant to drought – he is only active when the soil is moist.


Three Groups of Earthworms


All Earthworms are classified into only three ecological groups. This is made according to their localization in the soil, their feeding behavior, and their burrowing.

1. Epigeic Earthworms (1 to 2.5mm in diameter) They live not really in the ground but above the soil surface, squirming in or just below the plant litter – that means they rarely burrow and ingest the soil. These worms feed on leaves, fungi, and bacteria that help break down leaves. They have very little effect on soil structure.

2. Endogeic Earthworms (2 to 4.5mm in diameter) This group lives mostly on 10-15cm surface and dig extensive systems of burros to search for foods (decayed organic matter). Their burrows are mostly sub-horizontally oriented and after digging them, portions of them are immediately refilled with their casts.



3. Anecic Earthworms (4 to 8mm in diameter) They burrow deep into the soil, creating permanent channels up to several meters long. These burrows are more or less vertical and open to the soil surface. Periodically, they surface for leaf litter which they pull down into their burrows, let it decay there, and finally feed at the ground surface. You can find their worm casts sometimes on the surface.


Benefits of earthworms


Earthworms play an important role in the overall ecosystem in the soil – they are often referred to as ecosystem engineers. They are key to improving soil conditions. As mentioned earlier, the benefits are extremely dependent on which earthworm species you are dealing with. However, they all need sufficient organic matter and as little soil disturbance as possible to accomplish their tasks.

Here are listed some advantages of earthworms:

1. Soil aeration and promotion of root growth The numerous burrows increase the number of secondary pores (macropores) and thus contribute to good aeration of the soil. More than 90% of earthworms' burrows are colonized by plant roots. On the one hand, the roots can grow directly along the nutrient-rich worm casts in the burrows, and on the other hand, it is also much easier for the root to penetrate into deeper layers to find water, air, and nutrients.

2. Improving the infiltration of surface water Especially the permanent vertical burrows of the anecic species drastically improve not only surface water infiltration, but also water storage and drainage. Therefore, there is far less erosion. Soil with earthworms can hold up to 10 times more water than one without earthworms.

3. Incorporation of dead plant material Earthworms completely turn over the soil – fragmenting leaf and other plant debris, manure, mulch, or other waste, digesting and mixing it well. The soil is rejuvenated: valuable nutrients and organisms are brought to lower soil layers but minerals and nutrients from deeper layers also come to the top.

Some numbers: In a healthy meadow, 6 tons of dead plant material is incorporated by earthworms each year; in the forest, it's as much as 9 tons of foliage annually. And earthworms don't just think about themselves when they integrate the material – they also supply other soil organisms with valuable food.

4. Improvement of soil stability and crumb structure Despite the fact that the earthworm completely turns over the soil, it manages not only to loosen it but also to give it stability. Through the intensive mixing of organic and mineral material, microorganisms, and mucus secretions, earthworms form stable clay-humus complexes that improve the soil structure. So heavy soils become lighter and sandy soils more balanced.

5. Enrichment of nutrients The worm casts, which are formed either on the surface or in the topsoil, form stable crumbs. The organic and non-organic parts of the worm casts form the valuable clay-humus complexes, which on the one hand can hold the nutrients (and water) well, and on the other hand, they are immediately available to the plants at any time. Such worm casts contain on average 5 times more nitrogen, 7 times more phosphorus, and 11 times more potassium than the surrounding soil.

6. Carbon sequestration When decomposing organic material, the earthworm lowers the carbon: nitrogen ratio (C:N ratio). It also diligently contributes to sequestering carbon from the air in the soil and making it available to plants.

7. Cultivation of beneficial insects In the burrows and in the worm cases earthworms promote the colonization and increase of soil bacteria and fungi that act as naturally beneficial organisms. When they pull foliage into the burrows, some foliage diseases and pests also come along, which are eliminated naturally by these naturally beneficial organisms. Especially the fungal diseases that survive in the soil in winter are fought very well this way. In the earthworm itself also live numerous parasitic organisms of which some act as beneficial insects and are carried everywhere and often also delivered...


Invasive Earthworms


Earthworms govern their habitat in a very dominant way. They determine which plants can grow, which insects and other animals survive, and what the soil conditions are like.

In North America, for example, there is now a major problem: there are more and more "European" earthworms, but the diversity and quantity of other vertebrates has greatly diminished. In the forests, you also find few underplants as used to be the case. These "European" earthworms are simply not native there and were deliberately introduced by settlers. They change their environment there and adapt it for themselves, but at what price?

Never should earthworms be bred for fishing or worm compost be released into the wild.


How to increase Earthworms


Looking at all the benefits of earthworms, we can clearly see that earthworms work very specifically and are valuable and useful where they are at home. Therefore, it is important to promote the right groups of earthworms: Avoid soil compacting

  • Do not dig or till too much or unnecessarily; if possible, plow shallow only during the dry season, when earthworms retreat to deeper soil layers

  • Crop rotation

  • Do not use pesticides

  • Plant winter crops with green manure plants

  • Always keep the soil covered with mulch or interseeded crops

  • Provide sufficient food base in the form of organic material – leaves and plant residues after the season do not clean up everything, compost, manure,

  • Emergency solution: sow meadow for at least 2 years

For me, the earthworm is a very exciting living creature. Not only because it can accomplish so much through its ordinary little occupations in life. I would compare it to the life of a spirit-led Christian: It makes a big difference whether he is there or not. When he is there, he doesn't just think about himself but improves everything that is possible. He doesn't get on anyone's nerves – he lives and changes very quietly, continuously, and step by step. Just as every earthworm species has a special habitat, we too have a place prepared by God where we may live and work. Let us do this with the same zeal!



Christina Brandtner had the privilege to be trained as a gardener in an old little garden market. She has worked at TGM Austria for more than 10 years and is still gaining knowledge and practical skills in gardening and in working with students.









Pictures:

Garden Hen, Nigel Wedge from Fife, Scotland, CC BY 2.0, via Wikimedia Commons

Pulling an earthworm, hedera.baltica from Wrocław, Poland, CC BY-SA 2.0, via Wikimedia Commons

Hen running, Lilly M, CC BY-SA 3.0, via Wikimedia Commons

Soil clump, U.S. Department of Agriculture Lance Cheung/Photojournalist/USDA/Lance Cheung, Public domain, via Wikimedia Commons

permanent vertical burrow, North Appalachian Experimental Watershed, USDA-Agricultural Research Service, Coshocton, Ohio., Public domain, via Wikimedia Commons



65 views0 comments

Recent Posts

See All

Comments


  • YouTube
  • Instagram Social Icon
  • Adventist Agriculture Europe

© 2021 by Landscape Gardner. Proudly created with Wix.com

bottom of page