ISO 15958:2019 pdf download – Fertilizers — Extraction of water soluble phosphorus. 1 Scope This document specifies a method for the extraction of water soluble phosphorus. The method is applicable to all fertilizers, including compound fertilizers, where water soluble phosphorus is to be determined. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 1482-2, Fertilizers and liming materials...