RHP Potting Reference; a basic tool for application of growing media in pot and container cultures

J.B.G.M. Verhagen
Since 1999 EN 12580 is the European standard method to determine the quantity of soil improvers and growing media. Although this is a major step forwards in harmonised measurement of volume of growing media, it is still not related to practice. The amount of growing medium growers use to fill pots or containers varies a lot and is mostly not related to the delivered volume. Research carried out by RHP showed that the density in a pot or container can be 105 till 155% of the volume weight as determined by EN 12580 (1999), depending on crop, culture and grower. Research included measurement of delivered volume as well as measurement of the density of the growing medium after potting in various crops and pot/container types. Based on the results, the average compaction which growers realised compared to the EN 12580 volume weight, was worked into an indicator; 'the RHP Potting Reference', which can be determined by an additional measurement to EN 12580. By using a pressure plate the compacted volume is determined which relates to the average compaction growers do realise. This compacted value of a lot is related to the bulk volume measured by EN 12580. E.g., a potting reference value of 80% means that with 100 L growing medium, a pot volume of 80 L can be filled. As such the indicator was used to correct the quantity as given by EN 12580. The corrected quantity after using this new indicator gives a bench mark for much more even physical and nutritional aspects. It also improves the delivery of proper volumetric volumes of growing media at the grower's.
Verhagen, J.B.G.M. 2017. RHP Potting Reference; a basic tool for application of growing media in pot and container cultures. Acta Hort. (ISHS) 1168:101-106
http://www.actahort.org/books/1168/1168_14.htm
potting soil, RHP, growing media, volume, EN 12580, potting reference
English

Acta Horticulturae