NBN ISO 20620:2022

This document specifies a method for the determination of total nitrogen content in all nitrogen
containing fertilizers by combustion method.
NOTE 1 The presence of non-nutritive sources of nitrogen (e.g. chelating agents) causes positive bias to
samples being analysed for nutritive nitrogen content. The non-nutritive nitrogen content is subtracted from the
total nitrogen value to determine the nutritive nitrogen content.
NOTE 2 Common internationally traded fertilizers were evaluated for total nitrogen by combustion analysis
in the ring-study in this document. While the fertilizers analysed in this international ring study were mineral
fertilizers, previous studies have shown that total nitrogen by combustion is suitable for use with many non-
mineral, nitrogen-containing fertilizers.