ISHS Acta Horticulturae 150: International Symposium on Substrates in Horticulture other than Soils In Situ
PHYSICAL LABORATORY ANALYSES OF POTTING COMPOSTS. |
| Author: | G.A. Boertje |
| Abstract:
The physical qualities of potting composts are often assessed visually by taking into account such factors as the colour of the product, its elasticity and the presence or absence of fine peat particles. An important criterium for potting composts based on frosted decomposed black peat and peat moss is whether sufficient peat moss has been added to the mixture, since this type of peat has a favourable effect on the water and air balance in the compost and on the rate of shrinkage. The skill and experience of the assessor are of course of great importance. Different persons can form quite different opinions of the same batch of compost. A physical laboratory analysis of a potting compost is much more accurate and also more objective than a visual assessment, provided the analysis is carried out according to a standarised method. Laboratory analyses also offer the advantage that the analytical data can be rated according to scheduled quality specifications. Since 1 January 1983, samples of potting composts may be submitted for physical analysis to the laboratory of the Research Station at Naaldwijk. The samples are submitted mainly by potting compost manufacturers who are registered with the R.H.P., the Netherlands control system for commercial potting composts. The R.H.P. potting composts are required to meet certain standards which are described below. | |
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