Overview
ISO 23265:2022 - Soil quality - Test for estimating organic matter decomposition in contaminated soil specifies a laboratory procedure to evaluate the habitat function of soils by measuring effects of contaminants on organic matter decomposition (OMD). The method uses sterilized filter‑paper disks as a standardized cellulose substrate and estimates OMD from the mass loss of these disks after incubation in test and control soils. The standard is intended for natural soils and soils of unknown quality (e.g., contaminated sites, amended soils, remediated or agricultural sites) and for testing individual substances under temperate conditions.
Key topics and technical requirements
- Test principle: Compare decomposition (mass loss) of sterilized filter‑paper disks placed between soil layers in contaminated (test) and control/reference soils.
- Test design:
- Minimum of five replicates per treatment for control vs contaminated soil comparisons.
- Minimum of five sampling time points during incubation.
- Typical set‑up: pre‑weighed filter disks, 10 g dry mass soil below and 10 g above disk in a 50 ml sterile tube.
- Incubation at a constant temperature (example: 20 °C ± 2 °C).
- Validity and end points:
- Test completion criterion: control treatment should show ≥ 30% mass loss (with 40–70% ideal range) before final interpretation.
- Statistical endpoints: ECx, NOEC, LOEC, and limit test options are defined for chemically‑spiked soils.
- Limitations:
- Not applicable to substances with air/soil partition coefficient > 1.
- Not applicable to substances with vapour pressure > 300 Pa at 25 °C.
- The method does not include monitoring of substance persistence or stability during the test period.
- Referenced methods: Integration with routine soil analyses (pH, organic carbon, particle size, moisture) per ISO normative references.
Applications and users
This standard is practical for:
- Environmental laboratories performing ecotoxicity and soil quality assessments at contaminated sites and brownfields.
- Regulators and risk assessors evaluating the impact of soil contaminants on soil microbial function and carbon cycling.
- Remediation practitioners verifying restoration outcomes and soil health after remediation or amendment.
- Researchers studying microbial decomposition, carbon turnover, and soil ecosystem services.
Keywords: ISO 23265:2022, soil quality, organic matter decomposition, contaminated soil, filter paper test, soil microbial community, laboratory OMD test, chemically‑spiked soil.
Related standards
Normative references include: