ISO 23611-1:2018

Overview

ISO 23611-1:2018 - "Soil quality - Sampling of soil invertebrates - Part 1: Hand-sorting and extraction of earthworms" specifies a standardized field and handling method for sampling earthworms from terrestrial soils. The standard defines a combined hand‑sorting and chemical extraction (AITC) procedure as a prerequisite for using earthworms as bioindicators in soil quality assessment, ecological studies and pollutant-effect monitoring. It applies to all terrestrial biotopes where earthworms occur, but is not intended for semi‑terrestrial soils or some extreme climatic/geographical conditions.

Key topics and technical requirements

• Sampling principle: Combine physical hand‑sorting of an excavated soil block (example: 0.25 m² area, depth varying by land use - e.g. ~20 cm in crop sites) with a chemical extraction to maximize capture of surface and deep‑burrowing species.
• Extraction reagent: Allyl‑isothiocyanate (AITC) is recommended as the expellant (synthetic grade ~94–97%), replacing formalin due to health and environmental concerns.
• Reagents and preservation: Lists AITC, isopropanol, ethanol (70 % and 95 %), and formalin (4 % for storage only). Use 95 % ethanol when samples are intended for genetic analyses.
• Apparatus: Standard field and lab equipment plus specific items (plastic vessels 250–500 ml, sheeting 1–2 m², spade, forceps, balance sensitive to 0.01 g, dissecting microscope).
• Procedure overview: Timing of sampling (avoid extremes of low moisture/high temperature), individual storage of samples from each method, returning excavated soil to the plot, fixation and laboratory preservation, and biomass determination.
• Documentation: Data assessment and a detailed test report are required; annexes provide alternative methods, species determination guidance and monitoring examples.
• Limitations: Not suitable for semi‑terrestrial soils; may be difficult at high altitudes or extreme conditions.

Practical applications and users

ISO 23611-1 is used for:

• Soil quality monitoring and habitat assessment using earthworm abundance and biomass as indicators.
• Environmental impact and ecotoxicology studies, complementing ISO 11268‑3 guidance on pollutant effects in field situations.
• Long‑term biodiversity and bioindicator programs (research institutions, environmental agencies). Typical users: soil scientists, ecologists, environmental consultants, regulatory agencies, land managers and academic researchers conducting field sampling, soil biodiversity surveys and remediation decisions.

Related standards and references

• ISO 18400‑101 (sampling design of field studies)
• ISO 11268‑3 (effects of pollutants on earthworms in field situations)
• Other parts of the ISO 23611 series (methods for other soil organisms)
• Normative references cited in the standard: ISO 10390, ISO 10694, ISO 11260, ISO 11277, ISO 11465

Keywords: ISO 23611-1, soil quality, earthworm sampling, hand-sorting, AITC extraction, soil invertebrates, bioindicators, soil monitoring, sampling protocol.