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Earthworm abundance, biomass and diversity

  • Soil Health

  • Biological


Earthworms are sensitive to various management practices. Their presence not only signals a thriving ecosystem but also plays a crucial role in shaping it (Bispo et al., 2009; Griffiths et al., 2018; Pulleman et al., 2012).

The increase in earthworm populations corresponds to a rise in biopores, enhancing macroporosity and concurrently reducing denitrification while promoting an increase in soil organic carbon (SOC) (Bispo et al., 2009; Griffiths et al., 2018; Pulleman et al., 2012).

Earthworm abundances have also been positively correlated with water infiltration rates helping to counteract the effects of intense rain events on soil and plants (Griffiths et al., 2018).

Earthworms are also sensitive to pollutants, making them indicators of environmental health (Pulleman et al., 2012).

It is noteworthy that earthworms are not ubiquitous; coniferous forests, with their acidic soils, pose a less-than-ideal environment for earthworms. The same is true in waterlogged soils. In such cases, it might be prudent to consider an alternative biological indicator like enchytraeids (potworms), a taxonomically related yet typically smaller group of worms (Bispo et al., 2009).

Methodology summary

Step-by-step guide from the AHDB knowledge library:

  • Dig out a soil pit (20cm x 20cm x 20cm) and place soil on mat
  • Hand-sort the soil, placing each whole earthworm into the pot
  • Count and record the total number of earthworms
  • Separate earthworms into adults and juveniles
  • Return juveniles to the soil pit
  • Count and record the number of each type of adult earthworm
  • Return earthworms to the soil pit and backfill with soil
  • Repeat steps 1–7, until 10 soil pits per field have been assessed

Detailed information on how to count earthworms, with photographs and a video can be found following this link.

Detailed information on soil sampling such as where to take the samples from, how many, the best time to sample, and depth of sampling, can be found at the Farm Carbon Toolkit.

Metric threshold or direction of change

According to the AHDB, 16 or more earthworms as well as the presence of different ecological groups such as epigeic, endogeic and anecic, per soil pit indicates the soil is in good condition.

Technological innovations

Proximal soil sensing could be used in the future as it has been correlated with earthworm abundances in agricultural soils and could be used for modelling earthworm abundances at the field scale. It has the advantages of a rapid and large-scale data collection, allowing for repeated measurements over time without disrupting the soil ecosystem, reducing the need for labour-intensive manual sampling and sorting (Lardo et al., 2012; Schirrmann et al., 2016).

Future work is being done on image analysis methods, although is still in developmental stages.

Paper by Phillips et al, (2021) showcases current landscape of global earthworm analysis.


  • Agricultural
  • Forest
  • Grassland
  • Peatland
  • Saltmarsh
  • Wetland


  • Community
  • Population


  • Low


  • Tier 1

Technical expertise

  • Low

Standardised methodology

  • Yes