Plant biostimulants - Preparation of sample for microbial analysis

This document defines general rules for the aerobic preparation of the initial suspension and of dilutions for microbiological examinations of microbial plant biostimulants.
This horizontal method might not be appropriate in very detail for certain products. In this case, different methods which are specific to these products can be used if necessary, for justified technical reasons.

Pflanzen-Biostimulanzien - Probenvorbereitung für die mikrobielle Analyse

Dieses Dokument legt allgemeine Regeln für die aerobe Herstellung von Erstverdünnungen und Verdünnungen für mikrobiologische Untersuchungen von mikrobiellen Pflanzen-Biostimulanzien fest.
Dieses horizontale Verfahren ist für bestimmte Produkte nicht unbedingt bis ins Detail geeignet. In diesem Fall können andere Verfahren, die speziell auf diese Produkte zutreffen, angewendet werden, wenn dies aus gerechtfertigten technischen Gründen notwendig ist.

Biostimulants des végétaux - Préparation de l'échantillon pour l'analyse microbienne

Le présent document définit les règles générales pour la préparation aérobie de la suspension mère et des dilutions en vue de l’examen microbiologique des biostimulants microbiens des végétaux.
Cette méthode horizontale pourrait ne pas être appropriée dans le détail pour certains produits. Dans ce cas, des méthodes différentes, spécifiques à ces produits, peuvent être utilisées si cela s’avère nécessaire pour des raisons techniques justifiées.

Rastlinski biostimulanti - Priprava vzorcev za mikrobiološko analizo

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oSIST prEN 17708:2023
Rastlinski biostimulanti - Priprava vzorcev za mikrobiološko analizo
Plant biostimulants - Preparation of sample for microbial analysis
Pflanzen-Biostimulanzien - Probenvorbereitung für die mikrobielle Analyse
Biostimulants des végétaux - Préparation de l'échantillon pour l'analyse microbienne
Ta slovenski standard je istoveten z: prEN 17708
65.080 Gnojila Fertilizers
oSIST prEN 17708:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN 17708:2023
oSIST prEN 17708:2023
prEN 17708
April 2023
ICS 65.080 Will supersede CEN/TS 17708:2022
English Version
Plant biostimulants - Preparation of sample for microbial
Biostimulants des végétaux - Préparation de Pflanzen-Biostimulanzien - Probenvorbereitung für die
l'échantillon pour l'analyse microbienne mikrobielle Analyse
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 455.
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.



CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 17708:2023 E
worldwide for CEN national Members.

oSIST prEN 17708:2023
prEN 17708:2023 (E)
Contents Page
Introduction . 5
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Principle . 8
5 Diluents . 8
6 Apparatus . 8
7 Sampling and storage . 9
8 Preparation of samples and suspensions . 10
8.1 Protocol for enumeration of beneficial microorganisms . 10
8.1.1 General . 10
8.1.2 Liquid - water based - formulations . 10
8.1.3 Liquid - oil based (emulsifiable concentrate - EC) formulations . 10
8.1.4 Solid - wettable powder (WP) formulations . 10
8.1.5 Solid - water dispersible granules (WDG) formulations . 11
8.1.6 Solid - pellets, granules, microgranules (slow release) formulations . 11
8.1.7 Solid - substrate . 11
8.2 Protocol for enumeration of non-beneficial (including pathogens) microorganisms
................................................................................................................................................................ 11
8.2.1 General . 11
8.2.2 Liquid - water based - formulations . 11
8.2.3 Liquid - oil based (emulsifiable concentrate - EC) formulations . 11
8.2.4 Solid - wettable powder (WP) formulations . 11
8.2.5 Solid - water dispersible granules (WDG) formulations . 12
8.2.6 Solid - pellets, granules, microgranules (slow release) formulations . 12
8.2.7 Solid - substrate . 12
8.3 Protocol for the determination of anaerobic plate count . 12
8.3.1 General . 12
8.3.2 Liquid - water based - formulations . 12
8.3.3 Liquid - oil based (emulsifiable concentrate - EC) formulations . 12
8.3.4 Solid - wettable powder (WP) formulations . 12
8.3.5 Solid - water dispersible granules (WDG) formulations . 12
8.3.6 Solid - pellets, granules, microgranules (slow release) formulations . 12
8.3.7 Solid - substrate . 12
8.4 Protocol for the detection of pathogenic microorganisms . 13
8.4.1 General . 13
8.4.2 Liquid formulations . 13
8.4.3 Solid formulations . 13
8.5 Further dilutions . 13
8.5.1 Decimal dilution series . 13
8.5.2 Other dilutions series . 13
8.6 Duration of the procedure . 13
Annex A (normative) Plating procedure . 15
oSIST prEN 17708:2023
prEN 17708:2023 (E)
Annex B (normative) Diluents for general use . 17
B.1 General . 17
B.2 Peptone salt solution . 17
B.2.1 Composition . 17
B.2.2 Preparation . 17
B.3 Buffered peptone water . 17
B.3.1 Composition . 17
B.3.2 Preparation . 17
B.4 NaCl 0,9 % . 18
B.4.1 Composition . 18
B.4.2 Preparation . 18
B.5 PBS (Phosphate Buffered Saline) . 18
B.5.1 Composition . 18
B.5.2 Preparation . 18
Bibliography . 19

oSIST prEN 17708:2023
prEN 17708:2023 (E)
European foreword
This document (prEN 17708:2023) has been prepared by Technical Committee CEN/TC 455
“Plant Biostimulants”, the secretariat of which is held by AFNOR.
This document is currently submitted to the CEN Enquiry.
This document will supersede CEN/TS 17708:2022.
This document has been prepared under a Standardization Request given to CEN by the European
Commission and the European Free Trade Association.

oSIST prEN 17708:2023
prEN 17708:2023 (E)
This document was prepared by the experts of CEN/TC 455 “Plant Biostimulants”. The European
Committee for Standardization (CEN) was requested by the European Commission (EC) to draft
European standards or European standardization deliverables to support the implementation of
Regulation (EU) 2019/1009 of 5 June 2019 laying down rules on the making available on the
market of EU fertilizing products (“FPR” or “Fertilising Products Regulation”).
This standardization request, presented as SR M/564 and M/564 Amd1, also contributes to the
Communication on “Innovating for Sustainable Growth: A Bio economy for Europe”. The Working
Group 5 “Labelling and denominations”, was created to develop a work program as part of this
Request. The technical committee CEN/TC 455 “Plant Biostimulants” was established to carry out
the work program that will prepare a series of standards. The interest in biostimulants has
increased significantly in Europe as a valuable tool to use in agriculture. Standardization was
identified as having an important role in order to promote the use of biostimulants. The work of
CEN/TC 455 seeks to improve the reliability of the supply chain, thereby improving the confidence
of farmers, industry, and consumers in biostimulants, and will promote and support
commercialisation of the European biostimulant industry.
Biostimulants used in agriculture can be applied in multiple ways: on soil, on plant, as seed
treatment, etc. A microbial plant biostimulant consists of a microorganism or a consortium of
microorganisms, as referred to in Component Material Category 7 of Annex II of the EU Fertilising
Products Regulation.
This document is applicable to all microbial biostimulants in agriculture.
The Table 1 below summarizes many of the agro-ecological principles and the role played by
Table 1 — Agro-ecological principles and the role played by biostimulants [1]
Increase biodiversity
By improving soil microorganism quality/quantity
Reinforce biological regulation and interactions
By reinforcing plant-microorganism interactions
- symbiotic exchanges i.e. mycorrhizae
- symbiotic exchanges i.e. rhizobiaceae/fava
- secretions mimicking plant hormones (i.e. trichoderma)
By regulating plant physiological processes
- for ex growth, metabolism, plant development…
Improve biogeochemical cycles
- improve absorption of nutritional elements
- improve bioavailability of nutritional elements in the soil
- stimulate degradation of organic matter

oSIST prEN 17708:2023
prEN 17708:2023 (E)
This document defines the general rules for the preparation of samples, initial suspensions and
subsequent dilutions for microbiological examination of plant biostimulants.
Any special diluents or practices required in specific standard methods take priority over the
general rules listed in this document.

WARNING — Persons using this document should be familiar with normal

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