EN ISO 23611-1:2026

Overview

EN ISO 23611-1:2026 (Soil quality - Sampling of soil invertebrates - Part 1: Hand-sorting and extraction of earthworms) is an essential international standard developed by CEN and ISO for environmental professionals and laboratories dedicated to soil quality monitoring. This standard details standardized methods for sampling and handling earthworms from field soils, enabling their use as bioindicators to assess soil ecosystem health. By following the procedures described in this standard, stakeholders can ensure reliable, repeatable data on earthworm populations as a measure of soil biological quality.

The standard is designed for use in all terrestrial environments where earthworms are present but is not applicable to semi-terrestrial or aquatic environments such as bogs, marshes, and stream margins. Its methodologies form the foundation for routine ecological assessments, site comparisons, impact studies, and long-term monitoring of soil health.

Key Topics

• Standardized Sampling Methods: The document outlines robust techniques for both hand-sorting and chemical extraction of earthworms from field soils. A combination of these methods is recommended for comprehensive population assessments.

• Earthworm Extraction Techniques: The standard describes:

  • Hand-sorting of earthworms from defined soil plots,
  • Chemical expulsion using Allyl isothiocyanate (AITC) as a safer alternative to formalin,
  • Guidance on specimen preservation for taxonomic and molecular studies.

• Field and Laboratory Procedures: Practical guidance on equipment selection, record-keeping, and preservation (in ethanol or formalin), ensuring high-quality specimens and accurate biomass assessment.

• Site Assessment Parameters: Recommendations are given for supporting soil analysis, including pH, texture, organic carbon content, and cation exchange capacity, providing context for interpreting earthworm data.

• Categories of Earthworms: Definitions of major ecological types (endogeic, epigeic, and anecic) facilitate meaningful assessment across diverse habitats.

Applications

EN ISO 23611-1:2026 has wide-ranging applications for professionals concerned with soil biological evaluation:

• Bioindication & Soil Health Monitoring: Measuring earthworm abundance and biomass as indicators of habitat quality, soil fertility, and the effects of agricultural practices or remediation actions.

• Environmental Impact Assessment: Supporting compliance with regulations that require evidence-based evaluation of soil life, especially before and after site interventions.

• Long-term Monitoring Programs: Facilitating the integration of earthworm data into broad ecological surveys for trend analysis and reporting.

• Research and Ecotoxicology: Standardized earthworm sampling underpins studies on the impact of chemicals, land use, and climate change on soil ecosystems.

• Laboratory Analysis: Providing protocols for specimen preservation and preparation for subsequent morphological identification or genetic analysis (such as DNA metabarcoding).

Related Standards

This standard is part of a broader series, which together support comprehensive soil invertebrate sampling:

• ISO 23611 Series:

  • Part 2: Focuses on micro-arthropods
  • Part 3: Covers enchytraeids (mesofauna)
  • Part 6: Sampling of edaphic macrofauna

• Soil Quality Analysis:

  • ISO 10390: Determination of soil pH
  • ISO 10694: Determination of organic and total carbon
  • ISO 11277: Determination of particle size distribution
  • ISO 11465: Determination of dry matter and water content
  • ISO 11260: Cation exchange capacity

• Biological Testing & Identification:

  • ISO 21286: DNA barcoding of ecotoxicological test species
  • ISO 11268-3: Guidance on pollutant effects on earthworms in field samples

Practical Value

Implementing EN ISO 23611-1:2026 ensures harmonized soil sampling worldwide, reducing data variability and supporting the comparability of ecological and regulatory studies. Organizations following this standard can confidently contribute to global soil quality surveys, restoration projects, and research into the biological properties of soils, underpinned by reproducible and recognized approaches to earthworm sampling and analysis.