FprEN 17728

• Abstract:

  This document specifies references to methods to be used for the determination of specific parameters in organic soil improvers, but does not contain the methods themselves. The specific parameters in this document are:; — pH;; — electrical conductivity;; — organic carbon content;; — organic nitrogen content.; This document is applicable to the fertilizing product blends where a blend is a mix of two or more fertilising products belonging to the categories of fertilizers, liming material, soil improvers, growing media, inhibitors and plant biostimulants, and where organic soil improvers are the components with the highest percentage in the blend by mass or volume, or in the case of products in liquid form by dry mass. If the organic soil improvers are not the components with the highest percentage in the blend, the European Standard relevant to the component with the highest percentage in the blend applies. In case a blend is composed of fertilising products mixed in equal quantities, the user of the standard decides which standard to apply.; NOTE An organic soil improver consists of a single bulky (volume-building) component or a mix of bulky (volume-building) components (for example peat, wood fibres, coconut coir, compost).

• Status: Not Published
• Publication Date: 31-Jan-2027
• ICS: 65.080 - Fertilizers
• Technical Committee: CEN/TC 223 - Soil improvers and growing media
• Drafting Committee: CEN/TC 223/WG 6 - Harmonization
• Current Stage: 4599 - Dispatch of FV draft to CMC - Finalization for Vote
• Start Date: 19-Aug-2026
• Due Date: 26-Aug-2026
• Completion Date: 19-Aug-2026
• Directive: Not Harmonized2003/2003 - Regulation (EC) N° 2003/2003 of the European Parlament and of the council of 13 October 2003 relating to fertilisers
• Directive:

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  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
• Mandate: M/xxx - COMMISSION IMPLEMENTING DECISION of XXX on a standardisation request to the European Committee for Standardisation, the European Committee for Electrotechnical Standardisation and the European Telecommunications Standards Institute in support of the implementation of Commission Regulation (EU) 2025/2052 laying down ecodesign requirements for external power supplies, wireless chargers, wireless charging pads, battery chargers for portable batteries of general use and USB Type-C cables, pursuant to Directive 2009/125/EC of the European Parliament and of the Council and repealing Commission Regulation (EU) 2019/1782
• Ref Project: oSIST prEN 17728:2026 - Organic soil improvers - Methods for the determination of pH, electrical conductivity, organic carbon content and organic nitrogen content

• Revises: CEN/TS 17728:2022 - Organic soil improvers - Determination of specific parameters
• Effective Date: 20-Nov-2024

Overview

FprEN 17728 is a European standard developed by CEN for organic soil improvers, focusing on specifying the reference methods to determine key quality parameters: pH, electrical conductivity, organic carbon content, and organic nitrogen content. These parameters are critical for the evaluation and classification of organic soil improvers, widely used in agriculture, horticulture, landscaping, and soil remediation.

This standard is applicable to various fertilizing product blends where organic soil improvers are the predominant component by mass or volume (or dry mass for liquids). When organic soil improvers do not constitute the majority of the blend, the relevant standard for the dominant component applies. The user of the standard may decide which reference is most appropriate for mixtures in equal quantities.

FprEN 17728 supports compliance with EU Regulation (EU) 2019/1009 on fertilizing products, providing a recognized reference for assessing key compositional attributes of organic-based soil amendments.

Key Topics

• Quality Control: Establishes reference methods for assessing the most critical quality parameters in organic soil improvers, ensuring consistency and accuracy.
• Sampling and Sample Preparation: Specifies the need to follow established standards for representative sampling (EN 12579:2024) and sample preparation (prEN 13040-1:2025).
• Parameter Determination:
  • pH: Indicates the degree of acidity or alkalinity, essential for plant nutrient availability.
  • Electrical Conductivity: Reflects soluble salt content, affecting plant health and soil fertility.
  • Organic Carbon Content: Measures soil amendment's contribution to organic matter and soil structure.
  • Organic Nitrogen Content: Assesses nutrient value provided by the organic component.
• Applicability to Blends: Guides users on the relevant standard to apply for complex product mixtures containing fertilizers, soil improvers, and related inputs.

Applications

FprEN 17728 is vital for:

• Manufacturers and Processors: Provides assurance that organic soil improvers meet regulated quality parameters for EU market access.
• Testing Laboratories: Enables consistent procedures for analyzing organic amendments, supporting product certification, quality control, and research.
• Regulatory Compliance: Aids conformity with Regulation (EU) 2019/1009, by referencing harmonized methods for mandatory parameter determination.
• Blended Fertilizing Products: Offers a framework for selecting the appropriate methods when products contain multiple fertilizing categories (e.g., compost blends, manure-enriched media, growing substrates).
• Agricultural and Environmental Professionals: Supports best practices in soil health management, ensuring amendments improve soil productivity and sustainability.

Related Standards

FprEN 17728 references several related European standards that underpin each test method:

• EN 12579:2024 - Soil improvers and growing media - Sampling
• prEN 13037:2025 - Determination of pH
• prEN 13038:2025 - Determination of electrical conductivity
• prEN 13040-1:2025 - Sample preparation for chemical and physical tests
• prEN 18253:2025 - Determination of total organic carbon by dry combustion
• prEN 18255:2025 - Determination of organic nitrogen
• prEN 17732:2025 - Terminology for soil improvers and growing media

Adherence to these referenced standards ensures that measurement of pH, electrical conductivity, organic carbon, and organic nitrogen in organic soil improvers is accurate, repeatable, and aligned with European regulatory requirements.

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By providing harmonized reference methods, FprEN 17728 enhances product quality, facilitates regulatory compliance, and supports the sustainable use and trade of organic soil improvers throughout Europe.

SLOVENSKI STANDARD
01-april-2026
Organski izboljševalci tal - Metode za določanje pH, električne prevodnosti,
organskega ogljika in organskega dušika
Organic soil improvers - Methods for the determination of pH, electrical conductivity,
organic carbon content and organic nitrogen content
Organische Bodenverbesserungsmittel - Bestimmung spezifischer Parameter
Amendements organiques - Vue d'ensemble des méthodes pour la détermination du pH,
de la conductivité électrique, de la teneur en carbone organique et de la teneur en azote
organique
Ta slovenski standard je istoveten z: prEN 17728
ICS:
65.080 Gnojila Fertilizers
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
prEN 17728
NORME EUROPÉENNE
EUROPÄISCHE NORM
January 2026
ICS 65.080 Will supersede CEN/TS 17728:2022
English Version
Organic soil improvers - Methods for the determination of
pH, electrical conductivity, organic carbon content and
organic nitrogen content
Amendements du sol organiques - Méthodes pour la Organische Bodenverbesserungsmittel - Methoden zur
détermination du pH, de la conductivité électrique, de Bestimmung von pH-Wert, elektrischer Leitfähigkeit,
la teneur en carbone organique et de la teneur en azote organischem Kohlenstoffgehalt und organischem
organique Stickstoffgehalt
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 223.
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
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 17728:2026 E
worldwide for CEN national Members.

prEN 17728:2026 (E)
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Sampling and sample preparation . 6
4.1 Sampling . 6
4.2 Sample preparation . 6
5 Determination . 6
5.1 Determination of pH . 6
5.2 Determination of electrical conductivity . 6
5.3 Determination of the organic carbon content . 6
5.4 Determination of the organic nitrogen content . 6
Bibliography . 8

prEN 17728:2026 (E)
European foreword
This document (prEN 17728:2026) has been prepared by Technical Committee CEN/TC 223 “Soil
improvers and growing media”, the secretariat of which is held by NEN.
This document is currently submitted to the CEN Enquiry.
This document will supersede CEN/TS 17728:2022.
prEN 17728:2026 includes the following significant technical changes with respect to
CEN/TS 17728:2022:
— The title has been revised;
— The quantity requirements have been removed from the Introduction;
— An applicability statement has been included in the Scope;
— Clause 2, Normative references, has been updated;
— Clause 5.3, Determination of the organic carbon content, and Clause 5.4, Determination of the organic
nitrogen content, have been added;
— Annex ZA has been added.
This document has been prepared under a standardization request addressed to CEN by the European
Commission. The Standing Committee of the EFTA States subsequently approves these requests for its
Member States.
For the relationship with EU Legislation, see informative Annex ZA, which is an integral part of this
document.
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