Overview
ISO 18400-201:2017 - Soil quality - Sampling - Part 201: Physical pretreatment in the field specifies approved methods for physically pretreating soil samples immediately after collection, while still on site. The standard limits field pretreatment to: sample division (subsampling), production of composite samples, and selection of specific fractions of the sampled material. It expressly excludes procedures for biological/microbiological samples and sampling for volatile components, and it does not provide guidance on particle-size reduction (see related standards).
Key technical topics and requirements
- Scope and limits: Field pretreatment methods only; no particle size reduction; not applicable to biological or VOC-containing samples (ISO 22155 addresses volatiles).
- Preliminary considerations and sampling plan integration: Pretreatment actions must be defined in the sampling plan to preserve representativeness and traceability.
- Homogenization and subsampling: Procedures to obtain representative laboratory samples including homogenization principles and minimum subsample size requirements.
- Subsampling methods: Standardized field techniques described include:
- Long pile and alternate shovel
- Coning and quartering
- Riffling
- Tyler divider application
- Mechanized turntable (rotating divider)
- Selective subsampling by sieving or hand-picking to target specific particle-size fractions
- Macro-aggregate handling: Guidance for manual reduction of large aggregates to improve representativeness.
- Composite sample formation: Rules for combining increments or parts of samples to form a composite field sample.
- Equipment, safety, packaging and storage: Requirements for suitable field equipment, safe working practices, and interim packaging/storage to protect sample integrity until laboratory receipt.
- Reporting: Mandatory documentation of pretreatment actions, methods used, and sample identification to ensure traceability.
Practical applications and users
ISO 18400-201 is intended for professionals and organizations involved in soil investigation and environmental assessment, including:
- Environmental consultants and field technicians conducting contaminant surveys
- Geotechnical and agricultural soil sampling teams
- Laboratories receiving field-pretreated samples
- Regulatory agencies and remediation contractors specifying sampling protocols
Typical uses:
- Reducing large field samples to manageable laboratory samples while maintaining representativeness
- Creating composite samples from multiple increments for screening-level surveys
- Selecting targeted particle-size fractions for chemical analysis (where permitted)
Related standards
Using ISO 18400-201:2017 ensures consistent, defensible field pretreatment practices that protect sample integrity and support reliable soil quality assessments.