FprEN 13654-1

• Abstract:

  This document specifies a method for the determination of nitrogen in soil improvers and growing media. The Kjeldahl method determines ammonium-N, nitrate-N, nitrite-N and organic N content of soil improvers and growing media. Nitrogen in N-N-linkages, N-O-linkages and some heterocyclics (especially pyridine) is only partially determined [6], [7], [8].; 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 composted bark (20 mm to 40 mm, biowaste compost (Rottegrad 3), green compost (Rottegrad 5, 0 mm to 15 mm), solid digestate, liquid digestate, soil improver (pellets, sieved 4 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
• ICS: 65.080 - Fertilizers
• Technical Committee: CEN/TC 223 - Soil improvers and growing media
• Drafting Committee: CEN/TC 223/WG 4 - Analytical methods
• Current Stage: 4599 - Dispatch of FV draft to CMC - Finalization for Vote
• Start Date: 28-Jul-2026
• Due Date: 12-Oct-2024
• Completion Date: 28-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
• Mandate: M/XXX - M/XXX
• Ref Project: oSIST prEN 13654-1:2025 - Soil improvers and growing media - Determination of nitrogen - Part 1: Modified Kjeldahl method

• Revises: EN 13654-1:2001 - Soil improvers and growing media - Determination of nitrogen - Part 1: Modified Kjeldahl method
• Effective Date: 18-Jan-2023

Overview

FprEN 13654-1: Soil improvers and growing media - Determination of nitrogen - Part 1: Modified Kjeldahl method is a European standard developed by CEN for accurately determining the nitrogen content in soil improvers and growing media. This standard outlines a modified Kjeldahl method capable of quantifying ammonium-N, nitrate-N, nitrite-N, and organic N forms present in various soil amendments and substrates. The method provides essential data for producers, laboratories, and regulatory authorities responsible for quality control, labeling, and compliance of fertilizing products under relevant regulations such as the EU Fertilising Products Regulation (EU 2019/1009).

Key Topics

• Nitrogen Determination: The standard specifies laboratory procedures for measuring total nitrogen using a sulfuric acid–potassium sulfate digestion (the modified Kjeldahl method), followed by quantification of ammonium as the end product.
• Applicable Nitrogen Forms: The method measures ammonium, nitrate, nitrite, and organic nitrogen. It partially detects nitrogen in N-N and N-O linkages and some heterocyclic compounds (such as pyridine).
• Sample Handling: Guidance is provided on the preparation of both dried and fresh test samples, including grinding, sieving, and handling precautions to prevent nitrogen loss, especially in samples with high ammonium content.
• Quality Control: Instructions for running reagent blanks, use of verification substances with known nitrogen content, and reporting are included to ensure method reliability and traceability.
• Safety Requirements: Emphasizes laboratory safety, including working under fume hoods, and the use of personal protective equipment when handling hazardous reagents involved in the digestion process.

Applications

This standard is highly relevant in several essential areas:

• Product Quality Control: Producers of soil improvers, composts, digestates, and growing media use the method to determine nitrogen content for product specification, labeling, and market acceptance.
• Regulatory Compliance: Laboratories conducting conformity assessments for fertilizers and soil improvers rely on FprEN 13654-1 to ensure products meet legal requirements under the EU Fertilising Products Regulation.
• Research and Development: Researchers and agronomists employ the modified Kjeldahl method to analyze soil amendments in studies on crop nutrition and soil health.
• Trade and Certification: Ensures consistent and accurate nitrogen measurement across different countries, facilitating international trade of soil improvers and growing media.

Related Standards

The following standards and references are closely associated with FprEN 13654-1:

• CEN/TS 17732:2022 – Terminology for soil improvers and growing media
• EN 12579:2024 – Guidelines for sampling soil improvers and growing media
• prEN 13040-1:2025 – Sample preparation (drying, sieving, bulk density, and moisture determination)
• ISO 5725-2 – Methods for determining precision (repeatability and reproducibility) of measurement methods
• ISO 11261:1995 – Soil quality – Determination of total nitrogen – Modified Kjeldahl method
• Related methods: prEN 13651:2025 and prEN 13652:2025 for nutrient extraction in soil improvers and growing media

FprEN 13654-1 supersedes EN 13654-1:2001, improving clarity in methodological steps and referencing the latest normative and procedural developments. Adhering to this standard helps ensure reliable, precise nitrogen analysis in soil improvers and growing media, supporting both compliance and sustainable agricultural practices.

SLOVENSKI STANDARD
01-december-2025
Izboljševalci tal in rastni substrati - Določanje dušika - 1. del: Spremenjena
Kjeldahlova metoda
Soil improvers and growing media - Determination of nitrogen - Part 1: Modified Kjeldahl
method
Bodenverbesserungsmittel und Kultursubstrate - Bestimmung von Stickstoff - Teil 1:
Modifiziertes Verfahren nach Kjeldahl
Amendements du sol et supports de culture - Détermination de l'azote - Partie 1:
Méthode de Kjeldahl modifiée
Ta slovenski standard je istoveten z: prEN 13654-1
ICS:
65.080 Gnojila Fertilizers
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
prEN 13654-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2025
ICS 65.080 Will supersede EN 13654-1:2001
English Version
Soil improvers and growing media - Determination of
nitrogen - Part 1: Modified Kjeldahl method
Amendements du sol et supports de culture - Bodenverbesserungsmittel und Kultursubstrate -
Détermination de l'azote - Partie 1: Méthode de Bestimmung von Stickstoff - Teil 1: Modifiziertes
Kjeldahl modifiée Verfahren nach Kjeldahl
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 13654-1:2025 E
worldwide for CEN national Members.

prEN 13654-1:2025 (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 . 4
7 Sampling . 5
8 Test sample . 5
9 Procedure . 5
9.1 Safety . 5
10 Calculation . 7
10.1 General. 7
10.2 Calculation on a dry matter basis . 7
10.3 Calculation on a volume basis . 7
11 Expression of results . 7
12 Test Report . 8
13 Validation of the method . 8
13.1 Validation in accordance with ISO 5725-2. 8
13.2 Performance characteristics. 8
Annex A (informative) Performance characteristics of the method . 9
Bibliography . 11

prEN 13654-1:2025 (E)
European foreword
This document (prEN 13654-1:2025) 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 13654-1:2001.
prEN 13654-1:2025 includes the following significant technical changes with respect to
EN 13654-1:2001:
— Normative references have been adapted;
— The procedure has been described in more detail.
The Annex A is informative.
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 13654-1:2025 (E)
1 Scope
This document specifies a method for the determination of nitrogen in soil improvers and growing media.
The Kjeldahl method determines ammonium-N, nitrate-N, nitrite-N and organic N content of soil
improvers and growing media. Nitrogen in N-N-linkages, N-O-linkages and some heterocyclics (especially
pyridine) is only partially determined [6], [7], [8].
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 apply.
4 Principle
The nitrogen content of the sample is determined using a method based on a sulfuric acid/potassium
sulfate digestion. Copper sulfate is used as the catalyst.
5 Reagents
All reagents shall be of recognized analytical grade. Use water with a specific conductivity not higher than
0,2 mS/m at 25 °C, free from the elements to be determined.
5.1 Salicylic acid/sulfuric acid, dissolve 25 g of salicylic acid (HOC H COOH) in 1 000 ml of
6 4
concentrated sulfuric acid (⍴ = 1,84 g/ml).
5.2 Potassium sulfate catalyst mixture, grind and thoroughly mix 200 g of potassium sulfate, 6 g of
copper (II) sulfate pentahydrate (This mixture may be available commercially).
5.3 Sodium thiosulfate pentahydrate, crush the crystals to form a powder that passes through a sieve
with an aperture of 0,25 mm.
5.4 Verification substances, pure substances of known nitrogen content, for example acetanilide
(C H NO), L-aspartic acid (C H NO ), or amino acids of known composition. The total content of nitrogen
8 9 4 7 4
of the calibration substance should be as similar to the sample nitrogen content as possible.
6 Apparatus
Usual laboratory apparatus, and in particular the following:
6.1 Analytical balance, capable of weighing accurately to 1,0 mg.
6.2 Kjeldahl digestion flasks or tubes, of nominal value 50 ml, suitable for the digestion system (6.3).
prEN 13654-1:2025 (E)
NOTE Larger flasks (300 ml to 500 ml) might be necessary for bulky materials or where a larger sample mass
is used.
6.3 Digestion or mineralisation system with variable heating controls.
6.4 Sieve, 5 mm square aperture size.
6.5 Stand, capable of holding the digestion flasks or tubes.
7 Sampling
Sampling is not part of the method specified in this document. EN 12579:2024 shall be followed 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 Test sample
Either prepare the test sample in accordance with prEN 13040-1:2025, Clause 10 or use the sample as
received. Choose the respective calculation procedure (Clause 10).
Losses of nitrogen can occur with samples of high ammonium-N content in alkaline situations and
particularly when these samples are dried. If the sample contains (or is suspected to contain) > 500 mg/l
NH -N fresh basis, as determined by prEN 13651:2025 [1] or prEN 13652:2025 [2], analyse the fresh
material as soon as possible.
9 Procedure
9.1 Safety
SAFETY PRECAUTIONS — Care should be taken when handling samples that may contain sharps or are
of a dusty nature.
WARNING — Digestions with sulfuric acid are potentially hazardous and laboratory coats, gloves and
safety spectacles or goggles shall be used.
The digestion shall be carried out in a well-ventilated fume cupboard with the
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