Utility of Foamed Waste Glass as a Culture Medium for Horticulture

Abstract

In this experiment, we investigated the physical and chemical properties of foamed waste glass, and its application for the growth of Japanese mustard spinach (Brassica rapa L. Perviridis Group), in order to assess the utility of foamed waste glass as a culture medium for horticulture. Foamed waste glass with a particle size of less than 4 mm led to more favorable water availability than larger particle sizes. When mixing particles of less than 4 and 4–15 mm, the availability water was adjusted. The pH and exchangeable magnesium levels of foamed waste glass were higher than those of the commonly used culture medium of Masa (decomposed granite) and bark compost. On the other hand, CEC of foamed waste glass was lower than that of the common culture medium. The pH and exchangeable magnesium levels were both decreased by draining water, although the decrease of the pH was insufficient for cultivation. Foamed waste glass with an adjusted pH of 6 using dilute sulfuric acid led to the more favorable growth of Japanese mustard spinach than alkaline conditions. We conclude that foamed waste glass with a pH adjusted to 6 and with a particle size of less than 4 mm at rates of 25 to 75% is effective as a culture medium for horticulture.