AN INTERNATIONAL COMPARATIVE STUDY ON THE PHYSICAL AND CHEMICAL ANALYSIS OF HORTICULTURAL SUBSTRATES

G. Schmilewski, J. Günther
The knowledge of the physical and chemical properties of a horticultural substrate before and during crop cultivation is of fundamental importance to every grower.

Increasing international transactions on the substrate market, as well as the various declaration regulations in the different countries, place producers of horticultural substrates and substrate testing laboratories in urgent need of international standardization.

This paper describes how variable analytical results of one and the same growing medium can be when analysed at different institutes in different countries. 5 industrially produced substrates were tested at 23 laboratories in 12 countries. The substrates referred to are based on:

  1. weakly decomposed raised bog peat (white peat)
  2. frozen, highly decomposed raised bog peat (black peat) + white peat
  3. frozen, highly decomposed raised bog peat (black peat) + rockwool
  4. weakly decomposed raised bog peat + clay
  5. raised bog peat + composted bark

The physical and chemical analyses were performed according to the customary methods and specifications of the different countries. The analytical methods used do not only vary from country to country but also within a country. Consequently, the results obtained are rarely corresponding.

This international comparative study demonstrates clearly that…

  1. … the physical and chemical analyses results obtained, are subject to dispersion conditional on analytical methods.
  2. … customary analytical methods, and data resulting therefrom, do not allow horticultural assessments of substrates on an international basis.
  3. … published nutrient recommandations are not transferable referring to certain crops.

It should be the assignment in particular of the ISHS 'Commission for Plant Substrates' to stand up for the standardisation of analytical methods.

Schmilewski, G. and Günther, J. (1988). AN INTERNATIONAL COMPARATIVE STUDY ON THE PHYSICAL AND CHEMICAL ANALYSIS OF HORTICULTURAL SUBSTRATES. Acta Hortic. 221, 425-442
DOI: 10.17660/ActaHortic.1988.221.49
https://doi.org/10.17660/ActaHortic.1988.221.49

Acta Horticulturae