ISHS Acta Horticulturae 133: Nutrient Film Technique and Substrates, XXI IHC
PHYSICAL AND CHEMICAL COMPOSITIONS OF THE INACTIVE GROWING MEDIUM GRODAN° AND ITS FIELDS OF APPLICATION AND EXTENSION |
| Author: | J. Blaabjerg |
| Abstract:
GRODAN° was introduced into the Danish market in 1970. Today the growing medium GRODAN° is produced at the Rockwool factories in Denmark and in Holland. GRODAN° is a water absorbent mineral wool product which is produced as a granulate, as propagation blocks, growing blocks, and growing slabs. The thin mineral wool fibres with a diametre of 4 my are kept at a distance by means of the binder bakelit, and in this way the product will be structure stable. Despite the thin fibres the mineral wool particles are rather rough compared to soil particles, and the surface will therefore be smaller than for other growing mediums. This implies that almost all the water in the mediums is available to the plants. The basic material of mineral wool is diabase and on the whole the mineral fibres' chemical composition is corresponding to most compositions of soil minerals. The most important minerals are Silicium, Calcium, Aluminium, and Magnesium. The pH of the mineral wool varies from being neutral to slightly alkaline and this may easily be regulated during the fertilizer composition. At present GRODAN° is especially used for cultivation of tomatoes and cucumbers in Western Europe. The increasing use of GRODAN° to cut flowers and pot cultures shows that the product is about to get into new and very large fields of application. | |
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