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 tests includes main and trace nutrients (different forms of nitrogen, different forms of solubility for other nutrients and inorganic pollutants) according to test methods of the EU Fertilizer Regulation (VO(EC) 2003/2003), VDLUFA methods as well as EN and ISO standards. Participants receive a certificate documenting their performance in the various analyses. In Germany, the accreditation bodies require certificates from the testing laboratories about their successful participation in qualified fertilizer ring tests.
