prEN 15925

• Abstract:

  This document specifies a method for the extraction of the total sulfur contained in fertilizers in elemental form and/or in other chemical combinations.; The method is applicable to inorganic fertilizers for which a declaration of the total sulfur present in various forms (elemental, thiosulfate, sulfite, sulfate) is provided.

• Status: Not Published
• Publication Date: 13-Jan-2027
• ICS: 65.080 - Fertilizers
• Technical Committee: CEN/TC 260 - Fertilizers and liming materials
• Drafting Committee: CEN/TC 260/WG 7 - Chemical analysis
• Current Stage: 4599 - Dispatch of FV draft to CMC - Finalization for Vote
• Start Date: 16-Jul-2026
• Due Date: 01-Jan-2027
• Completion Date: 16-Jul-2026
• Directive: Harmonized Standard2019/1009 - Regulation (EU) 2019/1009 of the European Parliament and of the Council of 5 June 2019 laying down rules on the making available on the market of EU fertilising products and amending Regulations (EC) No 1069/2009 and (EC) No 1107/2009 and repealing Regulation (EC) No 2003/2003 (Text with EEA relevance)
• Mandate: M/564 - Fertilising products in support of Regulation (EU) 2019/1009
• Mandate: M/564 AMD 1 - amending Implementing Decision C(2020) 612 as regards certain harmonised standards and standardisation deliverables, deadlines for their adoption and the duration of the validity of the standardisation request
• Mandate: M/564 AMD 2 - Commission Implementing decision amending Implementing Decision C(2020)612 as regards harmonised standards, the deadlines for the adoption of those standards and the duration of the validity of the standardisation request to the European Committee for Standardisation as regards the EU fertilising products in support of Regulation (EU) 2019/1009 of the European Parliament and of the Council
• Ref Project: oSIST prEN 15925:2026 - Inorganic fertilizers - Extraction of total sulfur present in various forms

• Revises: EN 15925:2011 - Fertilizers - Extraction of total sulfur present in various forms
• Effective Date: 02-Apr-2025

Overview

The prEN 15925 standard, developed by CEN Technical Committee CEN/TC 260, specifies a precise method for the extraction of total sulfur present in various chemical forms within inorganic fertilizers. It addresses the analytical extraction of sulfur in elemental form and in compounds such as thiosulfate, sulfite, and sulfate. This standard is essential for controlling and verifying sulfur content in fertilizers, ensuring compliance with labeling requirements and quality regulations.

This document supersedes the previous EN 15925:2011 and incorporates important technical updates, including revised water quality parameters and improved procedural clarifications. prEN 15925 aligns with European regulatory frameworks, helping fertilizer manufacturers and testing laboratories maintain consistency and accuracy in elemental sulfur analysis.

Key Topics

• Scope and Applicability
  The method applies exclusively to inorganic fertilizers with declared sulfur content in multiple chemical forms: elemental sulfur, thiosulfate, sulfite, and sulfate. It defines extraction and determination protocols applicable throughout the fertilizer industry.

• Extraction Principle
  Elemental sulfur is first converted into polysulfides and thiosulfates in alkaline medium. Subsequent oxidation with hydrogen peroxide converts all sulfur forms into sulfate ions, which are then quantified using methods described in EN 15749.

• Reagents and Apparatus
  Required reagents include diluted hydrochloric acid, sodium hydroxide solution, hydrogen peroxide, and barium chloride solution of analytical grade, accompanied by distilled or demineralized water with strict conductivity limits (< 0.5 mS/m at 25 °C).
  Equipment includes electric hot plates, beakers, volumetric flasks, and filtration apparatus necessary for sample oxidation and sulfate determination.

• Procedure Overview
  The procedure involves weighing a representative sample, alkaline digestion with sodium hydroxide, oxidation with hydrogen peroxide, acidification, filtration, and sulfate measurement. Special instructions apply based on total sulfur concentration, ensuring accurate analysis for products ranging from low to high sulfur content.

• Test Reporting
  The standard mandates comprehensive reporting of results, including method reference, sample identification, sampling dates, full procedural details, and any relevant observations affecting results.

Applications

The prEN 15925 standard is vital for:

• Fertilizer Quality Control:
  Ensuring that sulfur content in inorganic fertilizers is accurately determined helps manufacturers comply with product specifications and regulatory requirements.

• Regulatory Compliance:
  Testing aligns with European fertilizer legislation, facilitating market approval and certification processes.

• Agricultural Efficiency:
  Precise sulfur analysis aids farmers and agronomists in choosing fertilizers with appropriate nutrient profiles, optimizing crop nutrition and yield.

• Research and Development:
  Laboratories developing new fertilizer formulations rely on standardized sulfur extraction methods for performance evaluation.

• International Trade:
  Harmonized analysis methods support consistent quality assessment across borders, simplifying certification and customs procedures.

Related Standards

prEN 15925 references and complements several key documents:

• EN 1482-2:
  Provides general provisions for sampling and sample preparation of fertilizers, essential for obtaining representative samples before sulfur extraction.

• EN 12944-1 and EN 12944-2:
  Define terminology related to fertilizers, ensuring uniform vocabulary in sulfur analysis and reporting.

• EN 15749:
  Specifies the determination of sulfate content using multiple analytical techniques-a critical step following sulfur extraction per prEN 15925.

This suite of standards collectively supports rigorous quality assurance and facilitates traceability and consistency in fertilizer sulfur testing.

---

Keywords: inorganic fertilizers, sulfur extraction, total sulfur determination, sulfur forms, fertilizer quality control, sulfur analytics, fertilizer sulfur content, prEN 15925, CEN standard, sulfur in fertilizers, fertilizer testing methods, sulfate analysis, chemical forms of sulfur

SLOVENSKI STANDARD
01-februar-2026
Anorganska gnojila - Ekstrakcija celotnega žvepla v različnih oblikah
Inorganic fertilizers - Extraction of total sulfur present in various forms
Anorganische Düngemittel - Extraktion von Gesamtschwefel, der in verschiedener Form
vorliegen kann
Engrais inorganiques - Extraction du soufre total présent sous différentes formes
Ta slovenski standard je istoveten z: prEN 15925
ICS:
65.080 Gnojila Fertilizers
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2025
ICS 65.080 Will supersede EN 15925:2011
English Version
Inorganic fertilizers - Extraction of total sulfur present in
various forms
Engrais inorganiques - Extraction du soufre total Anorganische Düngemittel - Extraktion von
présent sous différentes formes Gesamtschwefel, der in verschiedener Form vorliegen
kann
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 260.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 15925:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Sampling and sample preparation . 4
5 Principle . 4
6 Reagents . 4
7 Apparatus . 5
8 Procedure . 5
8.1 Test portion . 5
8.2 Oxidation . 5
8.3 Preparation of the solution to be analysed . 5
9 Test report . 6
Bibliography . 7

European foreword
This document (prEN 15925:2025) has been prepared by Technical Committee CEN/TC 260 “Fertilizers
and liming materials”, the secretariat of which is held by DIN.
This document is currently submitted to CEN Enquiry.
This document will supersede EN 15925:2011.
This document includes the following significant technical changes with respect to EN 15925:2011:
a) reference to EC fertilizer removed;
b) quality parameters for distilled water added;
c) clarification for covering with watch gl
...