Section III – Fertiliser Analysis – regularly conducts interlaboratory tests for the purpose of quality assurance and for validating and reviewing analytical methods. Over the past 25 years, this group has carried out internal interlaboratory tests to validate and assure the quality of assay methods for macronutrients and micronutrients, pollutants, nitrification inhibitors and other compounds. Tests performed in recent years include:
Since 2009, section III has offered an “VDLUFA EU Fertiliser Ring-Test” every year for EU accredited fertiliser testing laboratories in all countries. By participating in these test, laboratories can verify and document the quality of their analysis procedures. Between 28 and 48 laboratories from 21 member states and Turkey have participated over the past five years. To date, 9 interlaboratory tests have been performed on the following fertilisers:
The range of analytes includes macro- and micronutrients (different forms of nitrogen, diffent solubilities for other macronutrients; anorganic pollutants according to EU-regulation (VO(EG) 2003/2003), VDLUFA methods and EN- respectively ISO-norms.
The participants receive a certificate specifying their ranking in the different analyses. Accreditation bodies in Germany require that test laboratories provide certificates indicating their successful participation in qualified fertiliser tests.
