Earthworms - Architects of fertile soils

Their significance and recommendations for their promotion in agriculture

Author(s): 
Pfiffner, L 
Funders: 
CORE Organic II (TILMAN-ORG project)
Organisation: 
Research Institute of Organic Agriculture (FiBL)
Date: 
January 2014
Copyright: 
All rights reserved.
Evidence: 
Applied research

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Resource explained: 

Earthworms contribute to the health and biological activity of soils; their number and diversity is an important indication of soil fertility.

This technical guide (a TILMAN-ORG project output), gives an overview of the biology, ecology and multiple services earthworms provide, along with recommendations of how earthworms can be encouraged in agricultural soils.

There are sections on: 

  • Earthworm distribution and biology.
  • The impact of common agricultural practices on earthworm populations (which includes a quick reference table of worms that you can find in different habitats and soil layers, and descriptions of their feeding and living habits).
  • The many ways in which earthworms benefit soil fertility.
  • Agricultural practices that can enhance earthworms (including reduced tillage and ploughing, diversifying crop rotation and minimising soil compaction).
  • Guidance on estimating the number of earthworms in soil.
  • A list of selected literature on the impact of soil management on earthworms.

Findings & recommendations: 
  • ​A rich earthworm fauna is key to maintaining and safeguarding soil health and to fostering many essential ecosystem functions of soils.
  • Earthworms have a beneficial effect on soil fertility through aerating the soil, improving water infiltration and reducing surface run-off, decomposing dead plant matter, enhancing plant nutrients and the vitality of the soil, promoting colonisation and propagation of beneficial soil bacteria and fungi, promoting root growth and the formation of soil structure and stability, and contributing to carbon sequestration.
  • Heavy machinery, intensive tillage and use of pesticides can eliminate earthworms in fields.
  • Pesticides can have many detrimental effects on earthworms, with some species being more susceptible than others.
  • Herbicides have low toxicity for earthworms but can cause reduced populations. This fact sheet includes a chart showing the effects of fertilisation and pesticides in different farming systems on the number and the biomass of earthworms in a long-term trial.
  • For earthworms to flourish in agricultural soils, we need to:​
    • Provide sufficient food (plant material)
    • Abstain from using harmful pesticides
    • Practice soil-conservation methods i.e. reduced tillage and no-till
    • Establish well-structured and aerated soils
    • Practice appropriate site and crop fertilisation, balancing humus management within the crop rotation