CEN/TC 223/WG 5 - Microbiology

This document specifies a method for the enumeration of Escherichia coli (E. coli) in soil improvers and growing media. This document is applicable to material in solid form (including pre-shaped growing media) and liquid form.
This document is applicable to fertilizing product blends, where a blend is a mix of two or more fertilizing products belonging to the categories of fertilizers, liming material, soil improvers, growing media, inhibitors and plant biostimulants, and where soil improvers and/or growing media comprise the highest percentage in the blend by mass or volume, or in the case of liquid form by dry mass. If soil improvers and/or growing media do not comprise the highest percentage in the blend, the European Standard for the highest percentage in the blend applies. In case a blend is composed of fertilising products in equal quantity, the user of the standard decides which standard to apply.
NOTE 1   A soil improver or a growing medium consists of a single bulky (volume-building) component or a mix of bulky (volume-building) components (for example peat, wood fibres, coconut coir, compost, expanded perlite).
Strains of E. coli which do not grow at 44 °C ± 1 °C and, in particular, those that are β-D-glucuronidase-negative, such as E. coli O157, will not be detected. Some strains of Shigella spp. and Salmonella spp. within the family Enterobacteriaceae can also show β-D-glucuronidase activity at 44 °C ± 1 °C.
NOTE 2   This method has been validated in an interlaboratory study with specific products that were present on the market during the study (Annex C).