kSIST FprEN 17728:2026
(Main)Organic soil improvers - Methods for the determination of pH, electrical conductivity, organic carbon content and organic nitrogen content
- 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
- Public Enquiry End Date
- 19-Apr-2026
- Technical Committee
- KAT - Soil quality
- Current Stage
- 5020 - Formal vote (FV) (Adopted Project)
- Start Date
- 19-Oct-2026
- Due Date
- 07-Dec-2026
- Mandate
- M/XXX - M/XXX
kSIST FprEN 17728:2026 is the Slovenian adoption of the draft European Standard prEN 17728:2026, prepared by CEN. It specifies which test methods are to be used to determine pH, electrical conductivity, organic carbon content and organic nitrogen content in organic soil improvers. It is aimed at laboratories, manufacturers and conformity assessment users who need to check these parameters for compliance.
What does kSIST FprEN 17728:2026 specify?
kSIST FprEN 17728:2026 gives references to the methods used for the determination of specific parameters in organic soil improvers, but it does not reproduce the methods themselves. The document is organised into scope, normative references, terms and definitions, sampling and sample preparation, determination, and an informative Annex ZA linking the standard to EU legislation.
It also sets out when the document applies to fertilising product blends. In practice, this matters because the user must first decide whether the blend falls under this standard or under the standard for the component that is present in the highest proportion.
| Annex | What it covers |
|---|---|
| ZA | Relationship between this European Standard and Regulation (EU) 2019/1009 |
What are the key requirements of kSIST FprEN 17728:2026?
kSIST FprEN 17728:2026 is mainly a reference document, so its key requirements are about selecting the correct method and applying the correct supporting standards.
- Scope and applicability - The standard applies to organic soil improvers and to certain fertilising product blends where soil improvers and/or growing media are the dominant component by mass, volume, or dry mass for liquid products. If another component is dominant, the standard for that component applies instead. This tells the user which conformity route is relevant before any testing starts.
- Sampling - Sampling for quality control is carried out in accordance with EN 12579:2024. This matters because the laboratory result is only meaningful if the sample was taken correctly.
- Sample preparation - Sample preparation for chemical and physical tests follows prEN 13040-1:2025, Clauses 6 to 10. This ensures the test portion is prepared in a consistent way before measurement.
- pH determination - pH is determined according to prEN 13037:2025, Clause 9. Users should apply that method rather than inventing a local procedure.
- Electrical conductivity - Electrical conductivity is determined according to prEN 13038:2025, Clause 9. This gives a defined route for checking the soluble salt level of the product.
- Organic carbon content - Organic carbon content is determined according to prEN 18253:2025, Clause 8. This is the referenced method for assessing the carbon-related parameter used in the document.
- Organic nitrogen content - Organic nitrogen content is determined according to prEN 18255:2025, Clause 5. This provides the method reference for nitrogen-related compliance checking.
- Legislative link - Annex ZA connects the technical clauses to Regulation (EU) 2019/1009 for EU fertilising products. In practice, this is the part used when the standard is cited for presumption of conformity.
What terms does kSIST FprEN 17728:2026 define?
kSIST FprEN 17728:2026 relies on the terminology in prEN 17732:2025, so users should read that companion document for formal definitions.
- Organic soil improver - A bulky or volume-building component, or a mix of such components, such as peat, wood fibres, coconut coir or compost.
- Fertilising product blends - Mixtures of two or more fertilising products from the listed categories, with applicability decided by the dominant component.
- PFC 3A - The product function category used in the introduction for organic soil improvers under Regulation (EU) 2019/1009.
- pH - The acidity-related parameter that the standard routes to a specific test method.
- Electrical conductivity - The parameter used to indicate ionic content in the product extract or test solution, determined by a referenced method.
- Organic carbon content - The carbon-related parameter used in the referenced compliance assessment.
- Organic nitrogen content - The nitrogen-related parameter used in the referenced compliance assessment.
Who uses kSIST FprEN 17728:2026?
kSIST FprEN 17728:2026 is used by manufacturers of organic soil improvers, laboratories, and quality control teams that test product lots. It is also relevant to buyers, auditors and conformity assessment bodies that need a common method chain for checking product parameters.
It is especially useful in the fertilisers and soil improvers sector, including products placed on the market as EU fertilising products. The standard helps users decide how to sample, prepare and test products so that reported results are comparable.
What changed in kSIST FprEN 17728:2026 from the previous edition?
kSIST FprEN 17728:2026 will supersede CEN/TS 17728:2022. The foreword states these significant technical changes:
- the title was revised;
- quantity requirements were removed from the Introduction;
- an applicability statement was added to the Scope;
- Clause 2, Normative references, was updated;
- Clause 5.3 for organic carbon content was added;
- Clause 5.4 for organic nitrogen content was added;
- Annex ZA was added.
Which standards are used with kSIST FprEN 17728:2026?
The document refers to these companion standards:
- EN 12579:2024 - sampling for quality control.
- prEN 13037:2025 - determination of pH.
- prEN 13038:2025 - determination of electrical conductivity.
- prEN 13040-1:2025 - sample preparation for chemical and physical tests, including dry matter and moisture-related preparation steps.
- prEN 17732:2025 - terminology for soil improvers and growing media.
- prEN 18253:2025 - determination of total organic carbon by dry combustion.
- prEN 18255:2025 - determination of organic nitrogen.
What does the kSIST FprEN 17728:2026 document contain?
kSIST FprEN 17728:2026 contains the scope, referenced documents, terminology basis, sampling and sample preparation provisions, and four determination clauses covering pH, electrical conductivity, organic carbon content and organic nitrogen content. It also contains Annex ZA, which maps the standard to Regulation (EU) 2019/1009 and identifies the clauses used for presumption of conformity.
The document is a pointer standard rather than a full test manual. Its practical value is that it tells the reader which method to use for each parameter and which supporting standards to follow for sampling and preparation.
Relations
- Effective Date
- 01-Apr-2026
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Frequently Asked Questions
kSIST FprEN 17728:2026 is a draft published by the Slovenian Institute for Standardization (SIST). Its full title is "Organic soil improvers - Methods for the determination of pH, electrical conductivity, organic carbon content and organic nitrogen content". This standard covers: 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).
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).
kSIST FprEN 17728:2026 is classified under the following ICS (International Classification for Standards) categories: 65.080 - Fertilizers. The ICS classification helps identify the subject area and facilitates finding related standards.
kSIST FprEN 17728:2026 has the following relationships with other standards: It is inter standard links to SIST-TS CEN/TS 17728:2022. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
kSIST FprEN 17728:2026 is associated with the following European legislation: EU Directives/Regulations: 2003/2003, 2019/1009; Standardization Mandates: M/564, M/564 AMD 1, M/564 AMD 2, M/XXX. When a standard is cited in the Official Journal of the European Union, products manufactured in conformity with it benefit from a presumption of conformity with the essential requirements of the corresponding EU directive or regulation.
kSIST FprEN 17728:2026 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
oSIST prEN 17728:2026
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
oSIST prEN 17728:2026 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
oSIST prEN 17728:2026
oSIST prEN 17728:2026
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.
oSIST prEN 17728:2026
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
oSIST prEN 17728:2026
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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