PHYSICAL CHARACTERIZATION OF GROWING MEDIA USING STANDARD METHODS (CEN) - LIMITATIONS OF APPLICABILITY FOR PINE BARK AND VERMICULITE

CEN standards have helped to harmonize analytical methods for substrate analysis. Though, for special substrates or constituents the applicability might be limited. In this paper a comparative study of implementation of CEN standards to samples of pine bark and vermiculite has been carried out. For composted pine bark, an elongation of the equilibrium period up to 72 instead of 48 hours might increase the accuracy of determinations physical parameters according to EN 13041. For vermiculite, we suggest pycnometry as a feasible technique for the determination of particle density (PD), as the determination of organic matter (OM) as requested by EN 13041 for the calculation of the PD seems not to be applicable for this kind of material.