FprEN 18280

• Abstract:

  This document specifies a method for the enumeration of Escherichia coli (E. coli) in soil improvers and growing media. This document is applicable to material in solid form (including pre-shaped growing media) and liquid form.; This document is applicable to fertilizing product blends, where a blend is a mix of two or more fertilizing products belonging to the categories of fertilizers, liming material, soil improvers, growing media, inhibitors and plant biostimulants, and where soil improvers and/or growing media comprise the highest percentage in the blend by mass or volume, or in the case of liquid form by dry mass. If soil improvers and/or growing media 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 fertilizing products in equal quantity, the user of the standard decides which standard to apply.; This document does not apply to strains of E. coli which do not grow at 44 °C ± 1 °C and, in particular, those that are β-D-glucuronidase-negative, such as E. coli O157, which will not be detected. Some strains of Shigella spp. and Salmonella spp. within the family Enterobacteriaceae can also show β-D-glucuronidase activity at 44 °C ± 1 °C.; NOTE 1 A soil improver or a growing medium consists of a single bulky (volume-building) component or a mix of bulky (volume-building) components (for example peat, wood fibres, coconut coir, compost, expanded perlite).; NOTE 2 This method has been validated in an interlaboratory study with specific products (peat, biowaste compost, green compost and solid digestate) that were present on the market during the study (Annex C).

• Status: Not Published
• Publication Date: 14-Feb-2027
• ICS: 65.080 - Fertilizers
• Technical Committee: CEN/TC 223 - Soil improvers and growing media
• Drafting Committee: CEN/TC 223/WG 5 - Microbiology
• Current Stage: 4599 - Dispatch of FV draft to CMC - Finalization for Vote
• Start Date: 27-Jul-2026
• Due Date: 20-Nov-2025
• Completion Date: 27-Jul-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:

  ---

  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/588 - COMMISSION IMPLEMENTING DECISION of 20.9.2022 on a standardisation request to the European Committee for Standardisation as regards methods for the measurements of emissions into the air of polychlorinated dibenzo-pdioxins and furans (PCDDs/PCDFs) and dioxin-like polychlorinated biphenyls (PCBs), total gaseous mercury and formaldehyde in support of Directive 2010/75/EU of the European Parliament and of the Council
• Mandate: M/XXX - M/XXX
• Ref Project: oSIST prEN 18280:2026 - Soil improvers and growing media - Enumeration of Escherichia coli

Overview

FprEN 18280 is a draft European Standard developed by CEN (European Committee for Standardization) that specifies a reference method for the enumeration of Escherichia coli (E. coli) in soil improvers and growing media. This standard applies to both solid (including pre-shaped forms) and liquid materials, covering a broad range of fertilizing product blends used in agriculture and horticulture. The primary focus is on ensuring hygienic safety and supporting regulatory compliance related to the microbial quality of such products.

Effective enumeration of E. coli is crucial for monitoring faecal contamination and assessing the efficacy of sanitization and production processes in the manufacture of composts, peat-based substrates, digestates, and similar materials.

Key Topics

• E. coli Enumeration: The standard describes a culture-based method to determine the number of β-D-glucuronidase-positive E. coli colony-forming units (CFU) per gram or millilitre of product. This is achieved using selective media and conditions that favour the growth and detection of E. coli.

• Scope of Application:

  • Applies to soil improvers and growing media in both solid and liquid forms, including blends where these constitute the major component.
  • Excludes strains of E. coli that do not grow at 44 °C ± 1 °C, particularly β-D-glucuronidase-negative variants such as E. coli O157.
  • Addresses blends involving other fertilizing product categories (fertilizers, liming materials, inhibitors, plant biostimulants), specifying when this or other relevant standards should be applied.

• Testing Methodology: The procedure involves:

  • Preparation of samples according to referenced standards.
  • Enumeration on tryptone-bile-X-glucuronide (TBX) agar, followed by incubation.
  • Counting of characteristic blue colonies, with optional confirmation through biochemical tests.
  • Expression of results based on CFU per unit mass or volume.

• Quality Assurance: Laboratories are required to follow good microbiological practices, including quality controls and safety procedures. Reference is made to relevant international standards for laboratory practice and performance evaluation of media.

Applications

The method described in FprEN 18280 is of practical value in several contexts:

• Regulatory Compliance: Assists manufacturers and suppliers in meeting microbial safety criteria mandated by the EU Fertilising Products Regulation (EU 2019/1009) and similar national or regional requirements.
• Quality Assurance for Producers: Enables composting facilities, substrate manufacturers, and digestate producers to monitor and improve their sanitation processes by routinely testing for E. coli as an indicator organism.
• Environmental Safety and Consumer Protection: Reduces the risk of faecal contamination entering the food chain or environment via fertilizing materials applied to soil or growing crops.
• Validation of Blended Products: Ensures that blended soil improvers and growing media maintain microbiological quality, providing clear guidance on which standard is applicable in complex product formulations.

Related Standards

The use and interpretation of FprEN 18280 is supported by reference to a range of related standards:

• EN 12579: Soil improvers and growing media - Sampling
• prEN 13040-2: Soil improvers and growing media - Sample preparation for microbiological examination
• prEN 17732: Soil improvers and growing media - Terminology
• EN ISO 7218: Microbiology of the food chain - General requirements and guidance for microbiological examinations
• EN ISO 11133: Microbiology of food, animal feed and water - Preparation, production, storage and performance testing of culture media
• ISO 16649-2: Microbiology of food and animal feeding stuffs - Enumeration of β-glucuronidase-positive Escherichia coli

These standards help ensure consistency, reliability, and safety in the testing and production of soil improvers and growing media across Europe and internationally.

Keywords: soil improvers, growing media, E. coli enumeration, fertilizing product blends, CEN standards, microbial safety, compost quality, EU regulation, microbiological testing, TBX agar

SLOVENSKI STANDARD
01-januar-2026
Izboljševalci tal in rastni substrati - Ugotavljanje števila Escherichia coli
Soil improvers and growing media - Enumeration of Escherichia coli
Bodenverbesserungsmittel und Kultursubstrate - Bestimmung von Escherichia Coli
Amendements du sol et supports de culture - Dénombrement des Escherichia coli
Ta slovenski standard je istoveten z: prEN 18280
ICS:
65.080 Gnojila Fertilizers
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
prEN 18280
NORME EUROPÉENNE
EUROPÄISCHE NORM
January 2026
ICS 65.080
English Version
Soil improvers and growing media - Enumeration of
Escherichia coli
Amendements du sol et supports de culture - Bodenverbesserungsmittel und Kultursubstrate -
Dénombrement des Escherichia coli Bestimmung von Escherichia Coli
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 18280:2026 E
worldwide for CEN national Members.

prEN 18280:2026 (E)
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Principle . 6
5 Culture media and reagents . 6
6 Equipment and consumables . 6
7 Sampling . 7
8 Preparation of the test sample . 7
9 Procedure . 7
10 Expression of results . 9
11 Validation of the method . 10
12 Test report . 10
13 Quality assurance . 10
Annex A (normative) . 11
Annex B (normative) Composition and preparation of culture media and reagents . 12
B.1 General. 12
B.2 Tryptone-bile-X-glucuronide (TBX) agar . 12
B.3 MacConkey Agar No. 3 (optional) . 13
B.4 Tryptone/tryptophan medium (optional). 13
B.5 Kovacs reagent (optional) . 14
Annex C (informative) Performance characteristics of the method . 15
C.1 Interlaboratory study . 15
C.2 Statistical results for the enumeration of E. coli . 15
Bibliography . 18

prEN 18280:2026 (E)
European foreword
This document (prEN 18280:2026) 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 has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
prEN 18280:2026 (E)
Introduction
This document has been developed to enumerate E. coli in soil improvers and growing media in order to
be able to control certain hygienic requirements. The method described in this document is based on
EN ISO 16649-2 for the enumeration of β-D-glucuronidase-positive E. coli.
The species Escherichia coli is a Gram-negative bacterium of faecal origin that consists of a large number
of different strains. Consequently, it can be used as an indicator of faecal contamination and as a
parameter to evaluate the sanitation process during the manufacturing process of soil improvers or
growing media. The presence or absence of E. coli does not reflect the presence or absence of other
pathogens in the material tested.
WARNING — In order to safeguard the health of laboratory personnel, it is essential that tests for the
enumeration of E. coli are only undertaken in properly equipped laboratories, under the control of a
skilled microbiologist, and that great care is taken in the disposal of all incubated materials. Persons using
this document should be familiar with normal laboratory practice. This document does not purport to
address all of the safety aspects, if any, associated with its use. It is the responsibility of the user to
establish appropriate safety and health practices.
prEN 18280:2026 (E)
1 Scope
This document specifies a method for the enumeration of Escherichia coli (E. coli) in soil improvers and
growing media. This document is applicable to material in solid form (including pre-shaped growing
media) and liquid form.
This document is applicable to fertilizing product blends, where a blend is a mix of two or more fertilizing
products belonging to the categories of fertilizers, liming material, soil improvers, growing media,
inhibitors and plant biostimulants, and where soil improvers and/or growing media comprise the highest
percentage in the blend by mass or volume, or in the case of liquid form by dry mass. If soil improvers
and/or growing media do not comprise the highest percentage in the blend, the European Standard for
the highest percentage in the blend applies. In case a blend is composed of fertilising products in equal
quantity, the user of the standard decides which standard to apply.
NOTE 1 A soil improver or a growing medium consists of a single bulky (volume-building) component or a mix
of bulky (volume-building) components (for example peat, wood fibres, coconut coir, compost, expanded perlite).
Strains of E. coli which do not grow at 44 °C ± 1 °C and, in particular, those that are β-D-glucuronidase-
negative, such as E. coli O157, will not be detected. Some strains of Shigella spp. and Salmonella spp.
within the family Enterobacteriaceae can also show β-D-glucuronidase activity at 44 °C ± 1 °C.
NOTE 2 This method has been validated in an interlaboratory study with specific products that were present on
the market during the study (Annex C).
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 12579, Soil improvers and growing media - Sampling
prEN 13040-2, Soil improvers and growing media — Sample preparation — Part 2: Sample preparation
for microbiological examination
prEN 17732, Soil improvers and growing media — Terminology
EN ISO 7218, Microbiology of the food chain - General requirements and guidance for microbiological
examinations (ISO 7218)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in prEN 17732, prEN 13040-2 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/

Under preparation. Stage at time of publication: prEN 13040-2:2025.
Under preparation. Stage at time of publication: prEN 17732:2025.
prEN 18280:2026 (E)
3.1
Escherichia coli
bacteria which form typical blue colonies on tryptone-bile-X-glucuronide (TBX) agar (β-D-glucuronidase-
positive) at 44 °C ± 1 °C under the conditions specified in this method
3.2
enumeration of Escherichia coli
determination of the number of colony-forming units (CFU) of β-D-glucuronidase-positive Escherichia
coli per gram or per millilitre of product or per sample device, when the analysis and calculation is carried
out in accordance with this document
4 Principle
The initial suspension and/or aliquots of appropriate dilutions are used to inoculate the selective medium
tryptone-bile-glucuronide (TBX) agar through pour plating, which is incubated for 21 h ± 3 h at 44 °C.
After inoculation and incubation on TBX agar, β-D-glucuronidase-positive E. coli are enumerated and, if
necessary, confirmed by a positive indole reaction.
5 Culture media and reagents
Follow current laboratory practices in accordance with standards comparable to EN ISO 7218. The
composition of culture media and reagents and their preparation are specified in Annex B. For
performance testing of culture media, it is advised to follow the procedures of EN ISO 11133.
6 Equipment and consumables
Disposable equipment is an acceptable alternative to reusable glassware if it has suitable specifications.
The usual microbiological laboratory equipment (see ISO 7218) and, in particular, the following shall be
used.
6.1 Apparatus for dry sterilization (oven) and/or wet sterilization (autoclave).
6.2 Incubator(s), capable of maintaining a temperature of 36 °C ± 2 °C, 44 °C ± 1 °C and 44°C to 47°C.
6.3 Water bath, capable of maintaining a temperature between 44 °C and 47 °C.
6.4 Cooling unit, adjustable to 5 °C ± 3 °C.
6.5 pH-meter, capable of reading to the nearest 0,1 pH unit at 20 °C to 25 °C.
6.6 Sterile loops, of 10 μl volume (approximate diameter 3 mm) and of 1 µl volume, inoculating
needles or inoculating wires.
6.7 Sterile tubes, bottles or flasks with caps, of appropriate capacity.
6.8 Sterile Petri dishes, with a diameter of approximately 90 mm or a diameter of approximately
140 mm (optional).
6.9 Graduated pipettes or automatic pipettes and sterile tips, with wide opening if necessary, of
nominal capacities of 1 ml and 10 ml.
prEN 18280:2026 (E)
7 Sampling
Sampling is not part of the method specified in this document. Follow EN 12579 dealing with soil
improvers and growing media. It is important that the laboratory receives a sample that is representative
of the product under consideration. The sample should not have been damaged or changed during
transport or storage.
8 Preparation of the test sample
Prepare the test sample from the laboratory sample in accordance with prEN 13040-2. If there is no
specific International Standard available, it is recommended that the parties concerned come to an
agreement on this subject.
9 Procedure
9.1 General
The procedure as given in Annex A shall be followed.
The time elapsing between the start of the preparation of the initial suspension and the moment when
the plates are inoculated shall not exceed 45 min.
To check sterility, a control pour plate shall be prepared.
9.2 Preparation of the initial suspension and decimal dilutions
Preparation of the initial suspension and further decimal dilutions shall be performed according to
prEN 13040-2 .
Aliquots of the initial suspension should only be used for cultivation if no toxic or inhibiting substances
are expected in the sample. For blended products with high amounts of minerals, it is recommended to
−2
use aliquots from the first dilution (10 ) and higher. Liquid materials may be used undiluted if they do
not contain any toxic or inhibiting substances.
9.3 Inoculation and incubation on TBX agar
For enumeration, one plate per dilution shall be used with at least two successive dilutions. To improve
the reliability of the results, two plates per dilution are recommended.
If only one dilution is used, then two plates of this dilution shall be used to improve reliability of the
results.
For laboratories that do not operate under quality assurance principles, two plates per dilution shall be
used to improve reliability of the results.
Using a sterile pipette or a micropipette (6.9), 1 ml of the test sample (if liquid) or 1 ml of the appropriate
dilution shall be transferred to a sterile Petri dish (6.8).
Where greater dilutions are made and low counts are expected, the number of inoculated plates for
enumeration tests should be increased to ensure that an inoculation volume corresponding to at least
0,1 g of the sample is analysed. If the colony counts are expected to be close to a given limit value, it is
recommended to increase the accuracy of the method by adding 10 ml distributed into one pour-plated
Petri dish with a diameter of 140 mm, or at least three pour-plated Petri dishes with a diameter of 90 mm.
Approximately 15 ml (for 90 mm Petri dishes) or 45 ml (for 140 mm Petri dishes) of TBX agar (B.2),
cooled down to 44 °C to 47 °C in a water bath (6.3) or an incubator (6.2), shall be poured into each
Petri dish containing the respective volume of the test sample or an appropriate dilution.
prEN 18280:2026 (E)
The inoculum shall be carefully mixed with the medium and the mixture shall be allowed to solidify, with
the Petri dishes standing on a cool horizontal surface.
The time which elapses between the inoculation of the empty Petri dish and pouring of the med
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