oSIST prEN 16087-1:2025

Soil improvers and growing media - Determination of the aerobic biological degradation rate of organic matter - Part 1: Oxygen uptake rate (OUR)

This document describes a method to determine the stability of materials (e.g. compost, digestate) used as components (ingredients) in growing media, soil improvers and organic fertilisers by measuring the oxygen uptake rate (OUR). The oxygen uptake rate is a direct parameter for the degradation rate of biodegradable organic matter that is being broken down within a specified time period. The method is not suitable for material with a content of particle sizes > 20 mm exceeding 20 % by volume.
NOTE   The relation between the degradation rate and the oxygen uptake rate under the same conditions is depending on the type of material, for example by the C/N ratio. So it is important for the interpretation and limit values to be set based on the type of material.

Bodenverbesserungsmittel und Kultursubstrate - Bestimmung der aeroben biologischen Abbaurate organischer Substanz - Teil 1: Sauerstoffaufnahme (OUR)

Dieses Dokument beschreibt ein Verfahren zur Bestimmung der Stabilität von Materialien (z. B. Kompost, Gärrückstand), die als Bestandteile (Inhaltsstoffe) von Kultursubstraten, Bodenverbesserungsmitteln und organischen Düngemitteln verwendet werden, durch die Messung der Sauerstoffaufnahmerate (OUR, en: oxygen uptake rate). Die Sauerstoffaufnahmerate ist ein direkter Parameter für die Abbaurate von biologisch abbaubarer organischer Substanz, die innerhalb einer festgelegten Zeitdauer abgebaut wird. Das Verfahren ist nicht für Material geeignet, dessen Gehalt an Korngrößen > 20 mm einen Volumenanteil von 20 % überschreitet.
ANMERKUNG   Das Verhältnis zwischen der Abbaurate und der Sauerstoffaufnahmerate unter gleichen Bedingungen ist abhängig von der Art des Materials, zum Beispiel im Hinblick auf das C/N-Verhältnis. Es ist daher wichtig, Festlegungen zu Auswertung und Grenzwerten basierend auf der Art des Materials zu treffen.

Amendements du sol et supports de culture - Détermination de la cinétique de dégradation biologique aérobie de la matière organique - Partie 1 : Cinétique d’absorption de l’oxygène (OUR)

Le présent document décrit une méthode de détermination de la stabilité des matériaux (par exemple compost, digestat) utilisés comme composants (ingrédients) dans les supports de culture, les amendements du sol et les engrais organiques par mesurage de la cinétique d’absorption de l’oxygène (OUR). La cinétique d’absorption de l’oxygène est un paramètre direct de la cinétique de dégradation de la matière organique biodégradable qui est décomposée dans un laps de temps spécifié. La méthode ne convient pas à un matériau contenant plus de 20 % en volume de particules d’une granulométrie > 20 mm.
NOTE   La relation entre la cinétique de dégradation et la cinétique d’absorption de l’oxygène dans les mêmes conditions dépend du type de matériau, par exemple par le rapport C/N. Il est donc important que l’interprétation et les valeurs limites soient définies en fonction du type de matériau.

Izboljševalci tal in rastni substrati - Določanje aerobne biološke razgradljivosti organskih snovi - 1. del: Stopnja porabe kisika (OUR)

General Information

• Status: Not Published
• Public Enquiry End Date: 19-Dec-2025
• ICS: 65.080 - Fertilizers
• Technical Committee: KAT - Soil quality
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 17-Oct-2025
• Due Date: 06-Mar-2026
• Completion Date: 19-Dec-2025
• Directive: 2019/1009 - 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
• 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 Standardization, to the European Committee for Electrotechnical Standardization and to the European Telecommunications Standards Institute as regards certain measuring instruments in support of Directive 2014/32/EU of the European Parliament and of the Council
• Ref Project: prEN 16087-1 - Soil improvers and growing media - Determination of the aerobic biological degradation rate of organic matter - Part 1: Oxygen uptake rate (OUR)

Relations

• Revises: SIST EN 16087-1:2020 - Soil improvers and growing media - Determination of the aerobic biological activity - Part 1: Oxygen uptake rate (OUR)
• Effective Date: 01-Dec-2025

Overview

The oSIST prEN 16087-1:2025:2025 standard, developed by CEN, specifies a reliable laboratory method for determining the aerobic biological degradation rate of organic matter in soil improvers and growing media. This method focuses on measuring the oxygen uptake rate (OUR), which is a direct parameter reflecting how quickly biodegradable organic material breaks down aerobically. Target materials include composts, digestates, and organic fertilizers intended as ingredients for growing media and soil amendments. Importantly, the method excludes materials with particle sizes larger than 20 mm making up more than 20% by volume.

This standardized approach enables manufacturers, researchers, and environmental labs to accurately assess the stability and biodegradability of organic inputs, facilitating quality control and regulatory compliance. It also helps in optimizing soil improvers and growing media formulations to support sustainable agriculture and horticulture.

Key Topics

• Oxygen Uptake Rate (OUR) Measurement
  OUR measures how much oxygen is consumed by microorganisms during the aerobic decomposition of organic matter, reflecting the biological degradation rate over time.

• Applicable Materials
  Suitable for solid and liquid organic materials used as components in soil improvers and growing media, including compost and digestate samples.

• Sample Preparation
  Samples must be sieved to exclude oversized particles (>10 mm or >20 mm depending on the test variant), with moisture and organic matter content determined to calibrate measurements.

• Test Conditions
  Aerobic degradation is measured under controlled conditions at 20 °C ± 2 °C or 30 °C ± 2 °C. The procedure includes suspension of the sample in water, maintaining pH between 6.5 and 7.5, and inhibiting nitrification to focus on oxygen use by organic biodegradation.

• Instrumentation and Apparatus
  Key equipment includes a sealed reaction vessel with CO₂ absorbent, pressure transducers to detect oxygen consumption via pressure drops, and mixing devices to maintain uniform conditions.

• Data Interpretation
  The relationship between OUR and material degradation rates depends on factors such as C/N ratio; thus, limit values must be material-specific for accurate interpretation.

Applications

• Quality Control in Soil Improvement
  Ensures organic additives such as compost and digestate meet stability criteria before use in growing media or soil amendments, avoiding negative effects on plant health.

• Environmental Monitoring
  Assesses organic waste biodegradability for sustainable waste management, helping to optimize composting processes and reduce environmental impacts.

• Product Development
  Enables manufacturers to refine formulations of organic fertilizers and soil improvers by understanding degradation kinetics.

• Research and Regulation Compliance
  Supports scientific studies in soil biology and fulfills regulatory requirements for product stability and safety in horticultural and agricultural industries.

Related Standards

• CEN/TS 17732:2022 – Terminology related to soil improvers and growing media
• EN 12579:2024 – Sampling methods for soil improvers and growing media
• prEN 13039:2025 – Determination of organic matter content and ash in soil improvers
• prEN 13040-1:2025 – Sample preparation for chemical and physical testing in soil improvers

These complementary standards ensure consistent terminology, representative sampling, and accurate determination of material properties necessary for applying the OUR method effectively.

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Keywords: aerobic biological degradation, oxygen uptake rate (OUR), soil improvers, growing media, organic matter stability, compost testing, digestate analysis, biodegradable organic material, CEN standard, organic fertilizer quality, biodegradability assessment, environmental sustainability, soil amendment standards.

Standards Content (Sample)

SLOVENSKI STANDARD
01-december-2025
Izboljševalci tal in rastni substrati - Določanje aerobne biološke razgradljivosti
organskih snovi - 1. del: Stopnja porabe kisika (OUR)
Soil improvers and growing media - Determination of the aerobic biological degradation
rate of organic matter - Part 1: Oxygen uptake rate (OUR)
Bodenverbesserungsmittel und Kultursubstrate - Bestimmung der aeroben biologischen
Abbaurate organischer Substanz - Teil 1: Sauerstoffaufnahme (OUR)
Amendements du sol et supports de culture - Détermination de la cinétique de
dégradation biologique aérobie de la matière organique - Partie 1 : Cinétique
d’absorption de l’oxygène (OUR)
Ta slovenski standard je istoveten z: prEN 16087-1
ICS:
65.080 Gnojila Fertilizers
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2025
ICS 65.080 Will supersede EN 16087-1:2020
English Version
Soil improvers and growing media - Determination of the
aerobic biological degradation rate of organic matter - Part
1: Oxygen uptake rate (OUR)
Amendements du sol et supports de culture - Bodenverbesserungsmittel und Kultursubstrate -
Détermination de la cinétique de dégradation Bestimmung der aeroben biologischen Abbaurate
biologique aérobie de la matière organique - Partie 1 : organischer Substanz - Teil 1: Sauerstoffaufnahme
Cinétique d'absorption de l'oxygène (OUR) (OUR)
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 16087-1:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Principle . 4
5 Apparatus . 4
6 Reagents . 5
7 Sampling . 6
8 Procedure . 6
8.1 Safety . 6
8.2 Sample preparation for solid materials < 10 mm . 6
8.3 Sample preparation for solid materials < 20 mm . 7
8.4 Sample preparation for liquid materials . 7
8.5 Determination of moisture content and organic matter content . 7
8.6 Starting the procedure . 7
8.7 Respiration measurement . 8
9 Calculations . 9
9.1 Theoretical background . 9
9.2 Calculations . 9
10 Test report . 10
11 Validation of the method . 10
11.1 Validation in accordance with ISO 5725-2. 10
11.2 Performance characteristics. 10
Annex A (informative) Specific information on the OUR-test . 11
Annex B (informative) Incubation temperature. 13
Annex C (informative) Performance characteristics of the method . 14
Bibliography . 18

European foreword
This document (prEN 16087-1:2025) 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 16087-1:2011.
EN 16087-1:2011:
— For the balance (5.6) requirements have been added;
— Clarification of sample preparation (8.2) has been added;
— Formula (3) and 5 have been corrected;
— The figures in Annex A have been updated;
— The Bibliography has been corrected;
— The temperature of testing was for all products 30 °C but it has been changed. Products may be tested
at 20 or 30 °C. Background about the differences between the testing temperatures and the to choose
temperature can be found in Annex B.
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.
1 Scope
This document describes a method to determine the stability of materials (e.g. compost, digestate) used
as components (ingredients) in growing media, soil improvers and organic fertilisers by measuring the
oxygen uptake rate (OUR). The oxygen uptake rate is a direct parameter for the degradation rate of
biodegradable organic matter that is being broken down within a specified time period. The method is
not suitable for material with a content of particle sizes > 20 mm exceeding 20 % by volume.
NOTE The relation between the degradation rate and the oxygen uptake rate under the same conditions is
depending on the type of material, for example by the C/N ratio. So it is important for the interpretation and limit
values to be set based on the type of material.
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 13039:2025, Soil improvers and growing media — Determination of organic matter content and ash
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
EN 45501, Metrological aspects of non-automatic weighing instruments
3 Terms and definitions
For the purposes of this document, the terms and definitions given in CEN/TS 17732:2022 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/
4 Principle
The material is suspended in water. The respiration rate (i.e. oxygen uptake rate) is indirectly determined
by measuring the pressure drop in the headspace (i.e. gas phase in the closed space above the water
phase). The produced CO (carbon dioxide) is removed by a suitable alkaline absorbent. The
measurements are performed under defined conditions.
5 Apparatus
5.1 Testing facility
Temperature controlled room, climate cabinet or water bath, temperature adjustable to 20 °C ± 2 °C or
30 °C ± 2 °C.
5.2 Pressure transducer
Operating range 0 kPa to 20 kPa (accuracy ± 0,1 kPa) and record for measuring 2 to 4 times per hour for
seven days.
5.3 CO -absorbent containing unit
5.4 Reaction vessel
1 000 ml to 2 500 ml with a CO -absorbent containing unit (5.3) and the pressure transducer (5.2)
gastight connected (see Figure A.1).
5.5 Mixing device
Shaking Table 120 rpm ± 20 rpm or magnetic stirring unit and banded magnetic stirrer (see Figure A.2).
5.6 Balance
Meeting EN 45501 class II tolerances with a verification scale interval of 0,01 g.
5.7 pH meter
With slope adjustment and temperature control.
5.8 Dispenser
Dispensers or pipettes, adjustable units of 0,5 ml.
5.9 Glassware
Beakers and measuring cylinder.
5.10 Sieves
10 mm and 20 mm square aperture size.
5.11 Filter paper
Filter paper, with low ash content and high retentive properties.
6 Reagents
6.1 Water with a specific conductivity not higher than 0,2 mS/m at 25 °C
6.2 pH buffer
86 g/l KH PO , 89 g/l Na HPO ⋅ 2H O, mix ratio of 1:4 for pH 7; the solution is stable for 2 months if
2 4 2 4 2
stored at 1 °C to 5 °C. When a particulate precipitation is found a fresh solution is to be made.
Commercially available buffers may be used as well.
6.3 Macronutrient solution
Dissolve the following masses of chemical compounds in 1 000 ml water (6.1): 4,3 g NH Cl,
5,4 g CaCl ⋅ 2H O, 4,3 g MgSO ⋅ 7H O
2 2 4 2
The solution is stable for 2 months if stored at 3 °C ± 2°C. When a particulate precipitation is found a fresh
solution is to be made.
6.4 Micronutrient solution
Dissolve the following masses or volumes of chemical compounds in 1 000 ml water (6.1): 5,0 g EDDHA
iron chelate (60 g Fe/kg), 1,4 g MnSO , 1,1 g ZnSO , 4,2 g Na B O , 0,2 g CuSO , 0,13 g Na MoO ,
4 4 2 4 7 4 2 4
1 ml/l HCl (360 g/kg).
The solution is stable for 2 months if stored at 3 °C ± 2°C. When a particulate precipitation is found a fresh
solution is to be made.
6.5 Complete nutrient solution
Add 1 ml of micronutrient solution (6.4) to 1 000 ml of macronutrient solution (6.3). The solution is
stable for 2 months if stored at 3 °C ± 2°C. When a particulate precipitation is found a fresh solution is to
be made.
6.6 Nitrification inhibitor
4 g/l N-Allylthiourea, C H N S (ATU).
4 8 2
Store the solution in a closed container at 1 °C to 5 °C. The solution is stable for not more than 2 weeks.
6.7 CO -absorbent
Such as NaOH-pellets, KOH-pellets or soda lime (mixture of Ca(OH) , NaOH, KOH and water), preferably
with colour indicator.
NOTE Based on experience, 4,0 g of pellets (carbon dioxide absorption capacity > 200 g/kg) per container is
sufficient.
6.8 NaOH (0,5 mol/l)
6.9 HCI (0,5 mol/l)
6.10 Inoculum (to be added for materials without or low microbial activity)
–1 −1
Prepare an extract by shaking an active compost (OUR level 25 to 30 mmol O · kg · OM · hour ) with
water at mass:volume, 1:10 and filter it over a filter paper (5.11).
7 Sampling
Sampling is not part of the method specified in this document. Follow EN 12579:2024 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 Procedure
8.1 Safety
SAFETY PRECAUTIONS — Care should be taken when handling substances of caustic nature or samples
that may contain sharps or is of a dusty nature.
8.2 Sample preparation for solid materials < 10 mm
Take minimally 1 l of material. Manually, but carefully, break up lumps and agglomerates only that have
been caused by, for example, compress ion during transport. Break up lumps and agglomerates only and
pass the sample through a 10 mm sieve (5.10), gently agitating the material if required. Particles > 10 mm
shall not be broken up and shall be removed. Record the % mass of particles > 10 mm. If this amount
is > 20 % of the total fresh mass the procedure for materials < 20 mm (8.3) is to be followed. The moist
sample shall be stored at 3 °C ± 2 °C (total storage time max. 2 weeks).
8.3 Sample preparation for solid materials < 20 mm
Take minimally 1 l of material. Manually, but carefully, break up lumps and agglomerates only that have
been caused by, for example, compression during transport. Break up lumps and agglomerates only and
pass the sample through a 20 mm sieve (5.10), gently agitating the material if required. Particles > 20 mm
shall not be broken up and shall be removed. Record the % mass of particles > 20 mm. If this amount
is > 20 % of the total fresh mass, the test is not applicable. The moist sample shall be stored at 3 °C ± 2°C
(total storage time max. 2 weeks).
8.4 Sample preparation for liquid materials
Take minimally 1 l of material. Homogenize the sample by stirring. Break up lumps and agglomerates
only and pass the sample through a 10 mm sieve (5.10), gently agitating the material if required.
Particles > 10 mm shall not be broken up and shall be removed. Record the % mass of particles > 10 mm.
If this amount is > 20 % of the total fresh mass, the test is not applicable. The sample shall be stored at
3 °C ± 2 °C (total storage time max. 2 weeks). Stir the sample just before using it again.
8.5 Determination of moisture content and organic matter content
The moisture content shall be determined according to prEN 13040-1:2025 and the organic matter
content according to prEN 13039:2025, both determinations should take place after the sample
preparation.
8.6 Starting the procedure
For solid materials < 10 mm and liquid materials (8.2 and 8.4), calculate the mass of fresh material (EOM)
to be added to the reaction vessel based on 2 g of organic matter per litre according to Formula (1).
EOM g = (1)
( )
WW×
om d
where
W is the organic matter content, in % mass of the dried sample according to prEN 13039:2025;
om
W is the dry matter content, in % mass of the fresh sample according to prEN 13040-1:2025.
d
Calculate the required mass of sample (W ) to perform the test according to Formula (2).
S
W g EOM× C (2)
( )
S V
where
C is the capacity of the vessel in litres.
V
Place the calculated quantity of the sample in the clean reaction vessel (5.4). Add 180 ml water (6.1) and
10 ml complete nutrient solution (6.5) using a dispenser (5.8). Add 10 ml pH buffer (6.2) using a
dispenser (5.8). Add 2,5 ml nitrification inhibitor (6.6) using a dispenser (5.8). For materials without or
low microbial activity (e.g. wood fibre directly after production), 5 ml inoculum (6.10) can be added.
Then, measure the pH of the suspension. The value should be between 6,5 and 7,5. If this is not the case,
base or acid should be added (see 6.8 and 6.9). Place the sample on the mixing device (5.5) and start the
mixing for 4 h to 8 h in the conditioned room (5.1).
The analyses shall be performed at least
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