ISHS Acta Horticulturae 401: International Symposium on Growing Media & Plant Nutrition in Horticulture
PUMICE AS ENVIRONMENT-FRIENDLY SUBSTRATE - A COMPARISON WITH ROCKWOOL |
| Authors: | B. Gunnlaugsson, S. Adalsteinsson |
| Abstract:
Hekla-pumice is a natural and biologically inert material. It has been found to be a cheap alternative to other inert growing media e.g. rockwool and perlite. Because of its low water holding capacity growing beds with pumice have been designed with a 2–3 cm deep water reservoir at the bottom of each bed to assure adequate water supply to the plants. Irrigation has to be adjusted to give frequent watering with a small amount at a time. Because of some adherence of nutrient ions the pumice has to be soaked with a nutrient solution prior to planting. Pumice has some ion exchange capacity depending on which particle size is dominating the pumice mixture. The chemical adherence gives pumice chemical buffering capacity, releasing ions into the nutrient solution in the water- reservoir, which can be advantageous during rapid shifts in the nutritional demand of the plants. Yields of tomatoes grown in pumice and rockwool have been shown to be similar. Pumice can easily be sterilized with steam or other sterilizing agents and reused, which makes it an environment-friendly and economic alternative to other inert growing media. Tomatoes, cucumbers, paprikas, roses and gerberas are now successfully grown in pumice on a commercial scale in Iceland. | |
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