Overview
ISO 8634:1991 - "Solid fertilizers - Sampling plan for the evaluation of a large delivery" specifies a statistically based method for sampling and evaluating large fertilizer deliveries (applicable to deliveries of 250 t or more, e.g. full boat‑loads). The standard defines how to collect increments, form aggregate and reduced samples, perform laboratory analyses and apply decision rules that determine whether a delivery is acceptable for resale while accounting for prescribed buyer/seller risk levels. Annex A is integral; Annex B is informational. The sampling plan is based on the statistical study in ISO/TR 5307.
Key topics and technical requirements
- Scope and applicability: Designed for importers/resellers who receive large deliveries and will sell smaller lots under their responsibility.
- Sampling units and increments: Defines sampling unit (bag, grab, or time interval on continuous equipment) and how to take one increment per unit.
- Aggregate, reduced and final samples: Grouping increments k by k to create N' aggregate samples, then reducing each aggregate to laboratory final samples.
- Number of samples and analyses: Procedures to determine the number of increments (N), the number of aggregate samples (N') and grouping factor (k) using statistical parameters (risk levels α, β and related variables).
- Sampling methods for different presentations:
- Bagged fertilizer: Random bag selection, one increment per bag, grouping and reduction procedures.
- Bulk fertilizer (loading/unloading/transport/storage): Sampling during loading/unloading (grab or continuous apparatus), designation of sampling units and random selection.
- Equipment and bias control: Emphasis on using unbiased samplers (riffle, cone, rotary dividers) and avoiding elutriation/segregation during sampling and division.
- Documentation and reporting: Sampling report requirements (date/location, delivery details, number of increments, N and N', observations, conformity with ISO 8634).
- Analysis and evaluation: Requirement for separate analysis of each reduced aggregate sample and application of statistical decision rules to accept/reject deliveries.
Applications and users
ISO 8634 is used by:
- Importers, distributors and resellers of solid fertilizers
- Quality assurance and laboratory personnel performing fertilizer assays
- Regulatory and inspection authorities overseeing fertilizer trade
- Port/terminal operators and bulk handling personnel
- Agricultural co‑operatives and large buyers assessing incoming lots
Practical use: ensures defensible, reproducible sampling of large fertilizer deliveries for label claim verification, compliance checks and commercial acceptance decisions.
Related standards
Keywords: ISO 8634, solid fertilizers, sampling plan, large delivery sampling, fertilizer sampling, aggregate sample, sampling unit, statistical sampling for fertilizers.