Mineral fertilisers

At the Test Center Technology and Farm Inputs of DLG TestService, we certify mineral fertilisers in accordance with the product-specific DLG quality standard. In addition to the established criteria for this efficacy test, other product properties can be tested and certified. Mineral fertilisers that pass the tests receive the DLG quality seal. 

All DLG-certified farm inputs are subject to continuous monitoring. Consistent product quality is ensured through regular follow-up tests or analyses. In addition, random samples are taken at the manufacturer’s facility or in retail outlets.

Certification Concept

The certification of mineral fertilisers covers two levels: product testing (chemical and physical) and monitoring of the manufacturer’s internal production control (process control). Existing third-party audits may be recognised.

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Requirements for Manufacturers

  • Established quality management system
  • Internal production monitoring and self-testing
  • Spreading tables for all products to be certified

Monitoring Frequency

Inspections are carried out annually. From the third year onwards, the interval may be extended to two years if no deviations have been recorded. Spot-check product tests are conducted at both manufacturer and retail level.

Requirements

All tested products must comply with the requirements of the German Fertiliser Regulation (DüMV) and meet the quality parameters defined during the creation of the spreading tables.

DLG-Prüfkriterien

Chemical Analysis

The scope of testing depends on the type of fertiliser (N, P, NP, NK, PK, NPK). Parameters analysed include:

  • Nutrient contents (nitrogen, phosphate, potassium) – type-specific
  • Contaminants in all fertilisers: incl. arsenic, cadmium, lead, mercury, uranium, PFT
  • Micronutrients and secondary components depending on labelling

Physical Properties

Additional physical parameters are tested to assess spreading suitability:

  • Particle size distribution, crushing strength, dust content
  • Bulk density, surface texture, friction coefficient
DLG Medal Quality Seal

DLG-certified quality

The DLG quality seal stands for tested agricultural inputs. Regular testing ensures consistent quality. Special features or innovations can also be independently verified – visibly indicated directly on the certification mark.

T&C

Testing and Certification Ordinance

Complaint Management

Accreditations & Designations

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