In the first week of September ECN has published the 'Guidelines for Use of Quality Compost in Growing Media' as Part D of the ECN QAS Quality Manual. These guidelines set out suggested minimum quality criteria for compost when used as a constituent in horticultural growing media.
They apply to composted material prior to blending with other substrates and not the final growing medium mix. Additional quality criteria may therefore be required depending upon the intended use of the growing medium, especially if used in professional applications. Due to the wide range of potential growing media products, these guidelines are not intended to be prescriptive; instead they set out desirable quality criteria that are recognised as being important in the formulation of horticultural growing media.
Compost manufactured in accordance with this guideline will not be certified separately by ECN; compost certification remains subject to the Part C I (European Quality Assurance Scheme ECN-QAS for Compost).
In order for compost to be used as a constituent in growing media, additional quality criteria have been suggested. These are either more stringent, or are in addition to, the limit values specified in the ECN-QAS Quality Manual.
■ Material properties:
Organic matter content, Maximum particle size, Stability, pH value
■ Plant response tests
■ Physical contaminants (Undesired ingredients and properties):
Total of glass, metal & plastics, Stones, Weed seeds
■ Chemical properties:
Salinity / electrical conductivity, Na+, Cl-
The Guidelines can be downloaded here.
The ECN-QAS Manual can be downloaded here.