ISO 18644:2016 Checklist

Is the fertilizer in granular form?

Is it free-flowing (no clumping or sticking)?

Is it visibly free of moisture (no dampness or caking)?

Is it free of foreign matter (e.g., debris, contaminants)?

Does the controlled-release fertilizer meet the requirements from below and the values declared on the containers? • Is the mass fraction of total nutrient (N + P2O5 + K2O) ≧ 20%? • Is the particle size (1.00 mm to 4.75 mm) ≧ 90%? • Is the nutrient release period equal to the marked value? • Is the initial release rate of nutrients ≦ 15%? • Is the cumulative release mass fraction of nutrients in 28 days ≦ 75%? • Is the cumulative release mass fraction of nutrients during the nutrient release period ≧ 75%?

For single nutrient fertilizers (e.g., N, P, or K only): Is the mass fraction ≥ 18%?

For compound fertilizers: Is the total nutrient content (N + P₂O₅ + K₂O) ≥ 20%?

Are at least 90% of particles within the 1.00 mm to 4.75 mm range?

Are oversized (>4.75 mm) or undersized (<1.00 mm) particles minimal (<10%)?

Is appearance assessed visually by trained personnel?

Are observations documented consistently (e.g., color, texture)?

Total nitrogen: Is it tested per ISO 5315 (e.g., Kjeldahl method)?

Phosphorus (P₂O₅): Is it tested per ISO 6598 (e.g., spectrophotometric method)?

Potassium (K₂O): Is it tested per ISO 17319 (e.g., flame photometry)?

Is grain size measured using sieving per ISO 8397?

Is equipment calibrated and maintained?

Is the nutrient release rate tested per EN 13266?

Is the test conducted at the temperature specified on the label (e.g., 20°C, 25°C)?

Are multiple samples tested to ensure consistency?

Are laboratory samples approximately 1 kg in total mass?

Are samples split into two portions (one for analysis, and one for storage)?

Are samples stored in airtight containers to prevent moisture ingress?

Are the laboratory samples labeled according to ISO 7410, including: • Manufacturer name? • Product name and type? • Manufacturer’s reference and batch number or production date? • Lot size? • Date and place of sampling? • Signature of sampler and person from whose premises the sample was taken? • Stated release period (days) and temperature?

Are stored samples retained for at least 6 months?

Is sampling performed per ISO 8633 (solid fertilizers sampling)?

Are tools/techniques used to avoid damaging coatings (e.g., gentle scooping)?

Is sample reduction done per ISO 7742:1988 using riffle dividers or quartering?

Is the N-P-K formula (e.g., 20-10-10) specified?

Does the label include "controlled-release" or "coated controlled-release" as applicable?

Is the terminology consistent with product type (e.g., fully vs. partly controlled-release)?

Is the total nutrient content (e.g., % N, P₂O₅, K₂O) clearly marked?

Does it match the test results?

Are the specific controlled-release nutrients (e.g., coated N) identified?

Are their contents (e.g., 50% of total N) stated?

Does labeling meet ISO 7409 requirements (e.g., clear, durable marking)?

Does it comply with national/regional regulations?

Is the release period stated (e.g., 3 months, 6 months)?

Is the testing temperature for release specified (e.g., 25°C)?

(Optional) Are practical release curves provided?

Is the net mass declared on the package (e.g., 25 kg)?

Is the declared mass verifiable and consistent with contents?

Is the storage area dry (e.g., humidity controlled)?

Is it cool (e.g., below specified max temperature)?

Is it protected from sunlight (e.g., shaded or indoor)?

Are packages kept away from moisture sources (e.g., no leaks)?

Are procedures in place to protect against moisture (e.g., waterproof covers)?

Are packages shielded from direct sunlight during transit?

Are measures taken to prevent physical damage (e.g., stacking limits)?