| Raw Material Identity | Declared seaweed species or source category | Clearly identified; source, harvest period, and processing route documented for every lot | Review supplier specification, traceability records, and lot-level certificate of analysis | Different seaweed species and processing conditions can produce significantly different nutrient and mineral profiles. |
| Moisture | Water content of finished granules | Target approximately 6–10% by mass; confirm the agreed contract limit | Oven-drying method or validated moisture analyser; test at least one representative sample per lot | Excess moisture can cause caking, microbial growth, reduced storage stability, and inaccurate net nutrient calculations. |
| Particle Size | Granule diameter and size distribution | Typically 2–4 mm granules with at least 90% within the agreed size range | Mechanical sieve analysis using calibrated sieves | A narrow size distribution improves spreader performance, application uniformity, and compatibility with blended fertilisers. |
| Granule Strength | Resistance to breakage during handling | Low dust and fines; establish a product-specific crushing-strength or friability limit before purchase | Drop test, sieve-based attrition test, or validated granule-strength test after transport simulation | Weak granules generate dust and fines during loading, shipping, and spreading, which can lead to uneven field application. |
| Nutrient Declaration | Total nitrogen, phosphate, potash, calcium, magnesium, and sulphur where claimed | Declared values must match the destination market's fertiliser labelling rules and the contract specification | Independent laboratory analysis using validated methods such as combustion, spectrometry, or ICP analysis | Seaweed-based products naturally vary; verified declarations help buyers compare lots and calculate application rates correctly. |
| Organic Matter | Organic matter on a dry-matter basis | Use a contract-specific minimum; a practical screening target is often at least 35% for organic-based granules | Loss-on-ignition or another recognised organic-matter method, with the calculation basis clearly stated | Organic matter supports the positioning of the product as an organic-based soil amendment or fertiliser, subject to local rules. |
| pH and Salinity | pH and electrical conductivity of a defined water extract | pH commonly falls around 6.0–8.5; agree an electrical-conductivity limit for the intended crop and soil | Test a fixed water-to-product ratio and record the extraction time and temperature | pH and soluble salts influence blend compatibility, crop tolerance, and suitability for repeated use. |
| Heavy Metals | Lead, cadmium, arsenic, mercury, chromium, and nickel where required | Must comply with the legal limits of the importing country and the intended fertiliser category | Independent ICP-OES or ICP-MS testing using a documented digestion method | Seaweed can accumulate minerals from the marine environment; destination-country compliance is essential for market access and consumer safety. |
| Microbiological Safety | Salmonella, Escherichia coli, mould, yeast, and other regulated organisms | Absent or below the applicable legal limit for the destination market and product category | Accredited microbiological laboratory testing with sample handling and detection limits recorded | Microbiological controls reduce risks during storage, handling, and use, especially when the product contains other organic materials. |
| Contaminants and Foreign Matter | Sand, shells, plastic, stones, metal fragments, and other visible impurities | No visible foreign matter; define a maximum ash, sand, or insoluble-material limit where relevant | Visual inspection, sieving, ash analysis, and metal-detection controls at the production site | Foreign materials reduce product value, may damage application equipment, and can create regulatory or environmental concerns. |
| Batch Consistency | Variation between production lots | Compare at least three recent lots; key nutrient results should remain within the agreed specification range | Trend analysis of certificates of analysis, retain samples, and independent pre-shipment testing | Consistent results allow importers, distributors, and growers to maintain reliable application recommendations. |
| Packaging and Shelf Life | Protection from moisture, heat, pests, and physical damage | Moisture-resistant packaging, clear lot coding, production date, net weight, storage conditions, and a defined shelf-life statement | Inspect packaging integrity and verify that the lot code links to production and test records | Good packaging helps preserve granule flowability and reduces quality deterioration during international transport and warehouse storage. |
| Regulatory Documentation | Documents required for import, registration, and sale | Specification sheet, safety data sheet where applicable, certificate of analysis, origin documents, and destination-market compliance evidence | Pre-check documents with the importer, customs broker, and relevant fertiliser authority before shipment | Regulatory requirements differ by country; documentation gaps can delay customs clearance or prevent legal sale. |
| Storage and Transport Performance | Caking, dust generation, moisture pickup, and flowability after shipment | Granules should remain free-flowing after agreed transport and storage conditions are simulated | Conduct a packaging trial, humidity exposure check, and post-transport sieve and flowability assessment | International sea freight and warehouse humidity can alter granule performance even when the original factory sample was satisfactory. |