FprEN 18316

Inorganic fertilizers - Determination of the total K2O content by gravimetry and inductively coupled plasma optical emission spectrometry (ICP-OES)

Publication date:   Feb 26, 2026

Scope

This document specifies two different methods (Method A and B) for the determination of the content of potassium (expressed as K2O) in inorganic fertilizers. Method A specifies a gravimetric method. Method B specifies the method using inductively coupled plasma optical emission spectrometry (ICP-OES).
This document is applicable to fertilizing product blends, where the blend is a mix of at least two of the following components, fertilizers, liming materials, soil improvers, growing media, inhibitors and plant biostimulants, and where inorganic fertilizers are the highest % in the blend by mass or volume, or in the case of liquid form, by dry mass.
If inorganic fertilizers are not the highest % in the blend, the European Standard for the highest % of the blend applies. In case a fertilizing product blend is composed of components in equal quantity, the user decides which standard to apply.
NOTE Variations in analytical methods for fertilizing product blends can lead to differing results as some components or matrix interactions can affect the outcome. Validation procedures have shown that developed standard methods are robust and reliable across diverse product compositions, but possible interferences and unexpected results when analysing fertilizing product blends are possible.

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