Apply for approval as a laboratory to perform PLN soil analyses


In Wallonia, the quantity of Potentially Leachable Nitrogen (PLN) in our soils is tested each year by a thousand farmers. You need to be a laboratory approved by the Walloon administration to perform this type of analysis.

Are you a laboratory that wants to carry out PLN soil analyses recognised in Wallonia?

Ask for your approval, which is valid for five years and renewable (see "Procedure" below).

CRA-W: reference lab

This approval, which is mandatory, means that the methodology of the soil analyses carried out must be standardised and validated by the reference laboratory. In Wallonia, this is the Centre wallon de Recherches agronomiques (CRA-W).

Testing by farmers

Testing the nitrogen in our soils allows us to verify the amount of nitrogen fertiliser that the farmer has used. Following an analysis and comparison with the PLN values of the reference farms, the farmer will be declared in breach or not.

If they do not meet the requirements, they enter a two-year observation programme. The farmer then designates a laboratory approved by the administration to follow-up the soil analyses, at their own expense. If their soil test results are satisfactory for two consecutive years, they are removed from the observation programme. 

Avoiding the pollution of our soils

In Wallonia, it is the Department of Environment and Water (DEE) that issues the approvals as a PLN laboratory and manages the observation programmes. Our services ensure the preservation of the environment, avoiding the pollution of our groundwater and surface water by nitrogen.

In detail

Target audience – details

Any laboratory that performs soil analysis 


Management criteria for approval:

  • The form of the company or association may not hinder the independent exercise of the laboratory's activities vis-à-vis its clients
  • The head of the laboratory has the necessary scientific and technical qualifications and is completely independent of the companies with which the laboratory deals

Obligations as soon as you receive approval:

  • Participate in an inter-laboratory testing procedure coordinated by the reference laboratory to calibrate your analytical results three times a year 
  • Allow the agents of the Department of Environment and Water (DEE - SPW) to access the laboratory premises and consult all the documents related to the analyses and the accounting
  • Allow the head of the reference laboratory or their delegate to access the laboratory premises and consult all the documents relating to the analyses
  • Comply with the instructions published by the Belgian Institute for Standardisation and the DEE directives regarding the analysis conditions and the writing of the related protocols
  • Send the results of the analyses carried out as an approved laboratory to the reference laboratory or to the organisation in charge of assisting it, within the deadlines and in the forms fixed by this laboratory, to feed into a database on the subject
  • Not communicate to third parties other than the reference laboratory or the organisation in charge of assisting it, nor publish the results of the analyses, without authorisation from the Minister
  • Participate in inter-laboratory tests
  • Notify the DEE of any changes to the information provided in the approval application
  • Renew your approval application if the approved laboratory is transferred to another natural or legal person, or in the event of the merger or absorption of the legal person to which the approval was issued


There is no form to fill out to apply for approval. 

Send us your application:

  • Either via the email address:
  • Or by mail: SPW Agriculture Ressources Naturelles Environnement, Département de l'Environnement de l'Eau - CIAE - 15, Avenue prince de Liège, 5100 Jambes


  • the identity of the natural person or the legal status of the legal entity operating the laboratory for which approval is sought
  • the domicile or head and administrative offices of the applicant as well as the place of business of the laboratory
  • the name, occupation and position of the person who effectively manages the laboratory
  • if no ISO 17025 or BPL accreditation certificate is provided for soil nitric nitrogen analysis, a list of personnel performing the analysis and their professional qualifications
  • if no ISO 17025 or BPL accreditation certificate is provided for soil nitric nitrogen analysis, a description of the premises, equipment, scientific apparatus and documentation available to the laboratory


Once your request is complete, our department will send a copy of the application to the reference laboratory within one month of receiving it.


To demonstrate your competence, you must perform, at your own expense, blind analyses of six test objects from three reference materials. The six test objects are issued by the reference laboratory. 

The results of the analyses may not have margins of error greater than those set by the Minister, on the proposal of the Monitoring Committee. Margins of error are set and communicated to the applicant prior to the analysis.

  • IF your test results are satisfactory: the reference laboratory reports this to our services. You will then receive your approval within two months. The approval is notified by the Minister for a period of five years. It is only effective from the date of its publication in the Belgian Official Gazette.
  • IF your test results are unsatisfactory: you may, again at your own expense and within three months, perform a new series of blind tests on six test objects from three other reference materials. The six test objects are also issued by the reference laboratory. Approval is denied if the results of this second round of analyses are again unsatisfactory. A new application can only be submitted after one year of the date of notification of the refusal of approval.


An application for the renewal of approval may be submitted no later than three months before the expiry of the five-year period. Until a decision is taken on this application, the laboratory remains approved and can continue to carry out analyses. If no application for renewal is made under the specified conditions, the approval will automatically expire at the end of the five-year period.


Approval may be withdrawn by the Minister, temporarily or permanently, if:

  • the information provided does not correspond to the actual situation
  • the conditions (see "Conditions" section) are not met
  • the sampling procedures established by the Minister are not followed
  • the analysis results are systematically declared questionable, among other things on the basis of the opinion of the monitoring committee issued based on inter-laboratory tests

The laboratory receives a warning by registered letter prior to the withdrawal of approval. It is invited to present its defence within one month. Reasons are given for the withdrawal of approval. They are sent to the person concerned and published in the Belgian Official Gazette in extracts.


Until official approval is received, any laboratory that complies with all the technical requirements set by the Minister concerning it, and in particular the laboratories of the REQUASUD analysis and advisory network, may be considered as approved by the administration


An appeal is possible before the Supreme Administrative Court of Belgium.



Contact the Agriculture-Environment Integration Unit (CIAE) for any questions about PLN approval for laboratories
Updated on
Process n° : 145410
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