This document specifies the method for the determination of the EDTA soluble phosphorus content of inorganic fertilizers. The method is applicable for fertilizers composed of or blended from multiple sources such as superphosphate, ammonium phosphate, triple superphosphate, and/or nitrophosphate. It is not suitable for fertilizers containing calcium magnesium phosphates.st edition 2021-07 Fertilizers, soil conditioners and beneficial substances — Determination of EDTA soluble phosphorus content in inorganic fertilizers Engrais, amendements et substances bénéfiques — Détermination de la teneur en phosphore soluble dans l'EDTA dans les engrais inorganiques Reference number ISO 22018:2021(E) ？ ISO 2021 ISO 22018:2021(E) COPYRIGHT PROTECTED DOCUMENT ？