FprEN 13038
(Main)Soil improvers and growing media - Determination of electrical conductivity
- Abstract
This document specifies an instrumental method for the routine determination of electrical conductivity in a water extract of a soil improver or growing medium. The determination is carried out to obtain an indication of the content of water-soluble electrolytes in either soil improvers or growing media.
NOTE This method has been validated in an interlaboratory study with specific products that were present on the market during the study (as included in Annex A, being bark (Pinus pinaster, 20 mm to 40 mm fraction), coir pith (0 mm to 12 mm, washed and buffered), biowaste compost (Rottegrad 3), green compost (Rottegrad 5, 0 mm to 15 mm), liquid digestate, expanded clay, whole granules, 8 mm to 16 mm, growing media blend 1 (white peat, green compost, wood fibre, lime, inorganic fertilizer (NPK + micro elements)), growing media blend 2 (white peat, black peat, expanded perlite, lime, organic fertilizer) and growing media blend 3 (white peat, black peat, clay, inorganic fertilizer (NPK + micro elements))).
- Status
- Not Published
- Publication Date
- 13-Jan-2027
- Technical Committee
- CEN/TC 223 - Soil improvers and growing media
- Drafting Committee
- CEN/TC 223/WG 4 - Analytical methods
- Current Stage
- 5020 - Submission to Vote - Formal Approval
- Start Date
- 24-Sep-2026
- Due Date
- 28-Aug-2023
- Completion Date
- 24-Sep-2026
- Mandate
- M/XXX - M/XXX
FprEN 13038 is a CEN draft European Standard for soil improvers and growing media. It specifies an instrumental method for routine determination of electrical conductivity in a water extract, so the result gives an indication of the content of water-soluble electrolytes. It is intended for laboratories and other users who need comparable results for soil improvers and growing media.
What does FprEN 13038 specify?
FprEN 13038 specifies how to extract a sample with water, measure the electrical conductivity of the filtrate, and report the result as specific electrical conductivity corrected to 25 °C. Clause 7 points users to EN 12579:2024 for sampling, and Clause 8 links sample preparation to prEN 13040-1:2025.
The document is organized into these main parts:
- Clause 1 - Scope
- Clause 2 - Normative references
- Clause 3 - Terms and definitions
- Clause 4 - Principle
- Clause 5 - Reagents
- Clause 6 - Apparatus
- Clause 7 - Sampling
- Clause 8 - Preparation
- Clause 9 - Procedure
- Clause 10 - Test report
- Clause 11 - Validation of the method
- Annex A - Performance characteristics of the method
| Annex | What it covers |
|---|---|
| Annex A | Informative performance characteristics from the interlaboratory study |
What are the key requirements of FprEN 13038?
FprEN 13038 defines a controlled extraction and measurement method so different laboratories can compare results on the same kind of material. In practice, the important points are the sample condition, the extraction ratio, the calibration of the meter, and the way the result is reported.
Sampling and preparation
Clause 7 requires a representative sample and refers sampling to EN 12579:2024. Clause 8 requires preparation according to prEN 13040-1:2025 and determination of laboratory bulk density. For users, this means the conductivity result is only meaningful if the laboratory receives a sample that still represents the product and is prepared in a consistent way.
Extraction and measurement
Clause 4 states the principle: extract the sample with water at 22 °C ± 3.0 °C using an extraction ratio of 1 to 5, then measure the specific electrical conductivity and correct it to 25 °C. Clause 9 gives separate procedures for solid, pre-shaped, liquid and pasty materials. This matters because the method can be applied to different product forms without changing the measurement principle.
Calibration and apparatus
Clause 5 specifies the water and potassium chloride (KCl) solutions used for calibration, and Clause 6 lists the required equipment, including a conductivity meter with temperature correction, balance, thermometer, containers, shaker and filter paper. Clause 9.5 requires the cell constant to be checked with KCl solution and to stay within 5 % of the manufacturer value. For the laboratory, this is the step that keeps the meter set correctly and the results comparable.
Filtration and reporting
Clause 9.4 requires filtration before measurement, with alternative clarification methods allowed if paper filtration is too slow or impossible. Clause 10 requires the test report to identify the document used, identify the sample, state the result as whole numbers in mS/m, note any optional or non-specified operations, and include laboratory bulk density. In practice, this is what makes the result usable in quality control, specification checks and records.
Validation
Clause 11 states that the method was validated in accordance with ISO 5725-2 and that repeatability and reproducibility data are given in Annex A. This helps users judge whether the method is suitable for routine work on similar materials.
What terms does FprEN 13038 define?
- Electrical conductivity - the ability of an aqueous extract of the sample to conduct electricity as a function of ion concentration.
- Specific electrical conductivity - the conductivity value reported for the filtrate after correction to 25 °C.
- Potassium chloride (KCl) - the reference salt used to prepare calibration solutions for checking the conductivity meter.
- Laboratory bulk density - the density value determined during sample preparation and included in the test report.
- Repeatability - the closeness of results obtained under the same conditions in the interlaboratory study.
- Reproducibility - the closeness of results obtained across different laboratories in the interlaboratory study.
Who uses FprEN 13038?
FprEN 13038 is used by testing laboratories that measure soil improvers and growing media for routine quality control. It is also relevant to manufacturers and formulators of materials such as composts, peat blends, coir, bark, digestate and expanded clay, where electrical conductivity is used as an indicator of soluble salts. Buyers, specifiers and conformity assessment bodies can use the reported value to compare batches and document product characteristics.
What changed in FprEN 13038 from the previous edition?
FprEN 13038 will supersede EN 13038:2011. The foreword states one significant technical change: the scope and applicability have been adapted with respect to the EU-Fertilizer Product Regulation.
Which standards are used with FprEN 13038?
- CEN/TS 17732:2022 - provides the terminology used for soil improvers and growing media.
- EN 12579:2024 - gives the sampling rules that Clause 7 relies on.
- prEN 13040-1:2025 - gives sample preparation for chemical and physical tests and the determination of laboratory bulk density.
- ISO 5725-2 - provides the statistical basis used for validation, repeatability and reproducibility.
What does the FprEN 13038 document contain?
FprEN 13038 contains the reagents, apparatus and step-by-step procedure for extracting and measuring electrical conductivity in different material forms. It also includes the calibration step using KCl solutions, the filtration instructions, and the test report items that must accompany results. Annex A summarizes the interlaboratory study, including the nine materials used to assess performance characteristics. The document is therefore a working method for routine laboratory measurement, plus the validation information needed to judge its performance.
Relations
- Effective Date
- 19-Jan-2023
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Frequently Asked Questions
FprEN 13038 is a draft published by the European Committee for Standardization (CEN). Its full title is "Soil improvers and growing media - Determination of electrical conductivity". This standard covers: This document specifies an instrumental method for the routine determination of electrical conductivity in a water extract of a soil improver or growing medium. The determination is carried out to obtain an indication of the content of water-soluble electrolytes in either soil improvers or growing media. NOTE This method has been validated in an interlaboratory study with specific products that were present on the market during the study (as included in Annex A, being bark (Pinus pinaster, 20 mm to 40 mm fraction), coir pith (0 mm to 12 mm, washed and buffered), biowaste compost (Rottegrad 3), green compost (Rottegrad 5, 0 mm to 15 mm), liquid digestate, expanded clay, whole granules, 8 mm to 16 mm, growing media blend 1 (white peat, green compost, wood fibre, lime, inorganic fertilizer (NPK + micro elements)), growing media blend 2 (white peat, black peat, expanded perlite, lime, organic fertilizer) and growing media blend 3 (white peat, black peat, clay, inorganic fertilizer (NPK + micro elements))).
This document specifies an instrumental method for the routine determination of electrical conductivity in a water extract of a soil improver or growing medium. The determination is carried out to obtain an indication of the content of water-soluble electrolytes in either soil improvers or growing media. NOTE This method has been validated in an interlaboratory study with specific products that were present on the market during the study (as included in Annex A, being bark (Pinus pinaster, 20 mm to 40 mm fraction), coir pith (0 mm to 12 mm, washed and buffered), biowaste compost (Rottegrad 3), green compost (Rottegrad 5, 0 mm to 15 mm), liquid digestate, expanded clay, whole granules, 8 mm to 16 mm, growing media blend 1 (white peat, green compost, wood fibre, lime, inorganic fertilizer (NPK + micro elements)), growing media blend 2 (white peat, black peat, expanded perlite, lime, organic fertilizer) and growing media blend 3 (white peat, black peat, clay, inorganic fertilizer (NPK + micro elements))).
FprEN 13038 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.
FprEN 13038 has the following relationships with other standards: It is inter standard links to EN 13038:2011. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
FprEN 13038 is associated with the following European legislation: EU Directives/Regulations: 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.
FprEN 13038 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
01-november-2025
Izboljševalci tal in rastni substrati - Določanje električne prevodnosti
Soil improvers and growing media - Determination of electrical conductivity
Bodenverbesserungsmittel und Kultursubstrate - Bestimmung der elektrischen
Leitfähigkeit
Amendements du sol et supports de culture - Détermination de la conductivité électrique
Ta slovenski standard je istoveten z: prEN 13038
ICS:
65.080 Gnojila Fertilizers
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
DRAFT
EUROPEAN STANDARD
prEN 13038
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2025
ICS 65.080 Will supersede EN 13038:2011
English Version
Soil improvers and growing media - Determination of
electrical conductivity
Amendements du sol et supports de culture - Bodenverbesserungsmittel und Kultursubstrate -
Détermination de la conductivité électrique Bestimmung der elektrischen Leitfähigkeit
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
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 13038:2025 E
worldwide for CEN national Members.
prEN 13038:2025 (E)
Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Principle . 4
5 Reagents . 4
6 Apparatus . 5
7 Sampling . 5
8 Preparation . 5
9 Procedure . 5
9.1 Extraction of materials in solid form . 5
9.2 Extraction of material in pre-shaped form . 6
9.3 Extraction of liquid or pasty materials . 6
9.4 Filtration . 6
9.5 Measuring conductivity of the potassium chloride solutions . 6
9.6 Measurement of the specific electrical conductivity of the filtrates . 6
10 Test report . 7
11 Validation of the method . 7
11.1 Validation in accordance with ISO 5725-2. 7
11.2 Performance characteristics. 7
Annex A (informative) Performance characteristics of the method . 8
Bibliography . 10
prEN 13038:2025 (E)
European foreword
This document (prEN 13038:2025) 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 EN 13038:2011.
prEN 13038:2025 includes the following significant technical changes with respect to EN 13038:2011:
— adaption of scope and applicability with respect to the EU-Fertilizer Product Regulation [3].
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.
prEN 13038:2025 (E)
1 Scope
This document specifies an instrumental method for the routine determination of electrical conductivity
in a water extract of a soil improver or growing medium. The determination is carried out to obtain an
indication of the content of water soluble electrolytes in either soil improvers or growing media.
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.
CEN/TS 17732:2022, Soil improvers and growing media – Terminology
EN 12579:2024, Soil improvers and growing media - Sampling
prEN 13040-1:2025, Soil improvers and growing media — Sample preparation — Part 1: Sample
preparation for chemical and physical tests, determination of dry matter content, moisture content and
laboratory bulk density
3 Terms and definitions
For the purposes of this document, the terms and definitions given in CEN/TS 17732:2022 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp/
— IEC Electropedia: available at https://www.electropedia.org/
3.1
electrical conductivity
ability of an aqueous extract of the sample to conduct electricity as a function of the ion concentration
4 Principle
A sample is extracted with water at 22 °C ± 3,0 °C in an extraction ratio of 1 to 5 (1 V sample + 5 V water)
to dissolve the electrolytes. The specific electrical conductivity of the extract is measured and the result
is adjusted to a measurement temperature of 25 °C.
5 Reagents
5.1 Water, having an electrical conductivity not higher than 0,2 mS/m at 25 °C.
5.2 Potassium chloride solution, c(KCl) = 0,100 mol/l.
Dissolve 7,456 g potassium chloride (KCl), previously dried for 2 h at 105 °C, in water (5.1) and dilute to
1 000 ml. The specific electrical conductivity of this solution at 25 °C is 1 290 mS/m.
5.3 Potassium chloride solution, c(KCl) = 0,0100 mol/l.
Add 100,0 ml of potassium chloride solution (5.2) into a 1 000 ml volumetric flask and dilute to the
1 000 ml mark with water (5.1) at 20 °C. The specific electrical conductivity of this solution at 25 °C is
141 mS/m.
...