ISHS Acta Horticulturae 644: International Symposium on Growing Media and Hydroponics
CEN-METHODS (EUROPEAN STANDARDS) FOR DETERMINING PLANT AVAILABLE NUTRIENTS - A COMPARISON |
| Author: | A. Baumgarten |
| Keywords: | CEN, CaCl2/DTPA extract, water extract, extraction ratio, plant available nutrients |
| Abstract:
Recently, a number of methods for the determination of physical and chemical properties of growing media have been published by the Comité Europeén de Normalisation (CEN), thus replacing all corresponding national standards in CEN-member-countries. As a widespread use of the new stan¬dards shall be achieved, these methods were compared to methods currently used in the routine analysis. 20 different growing media were analysed for pH, electric conductivity and "available" nutrients, using both CEN standards and "routine" methods. As the results for elements are expressed on a mass/volume basis, both the CEN-standard (compaction by an exter¬nal weight) and the "routine"-method (self compaction) were used for the determination of the bulk density. For the physical methods, good relationships could be found, although absolute figures differed markedly. For the bulk density, only about 75% of the density determined by self compaction could be stated using the external compression. pH determination in water gave higher results as compared to the measurement in CaCl2-suspension. EC showed higher values if using the former routine method. Surprisingly, similar results for the mass/volume and volume/volume-extraction procedure could be found, if using the corresponding method for the determination of the bulk density. Consequently, it seems possible for routine analysis to use the more convenient method with fixed masses for weighing. Furthermore, the use of existing guidelines for interpretation based on the 1+8 (M/V) CAT-extract seems to be possible for most of the elements determined by the new CEN-methods. | |
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