Oleh: Suwardi and Itsuo Goto (1996)
Growth medium is one of the most importance factors to produce high quality of seed and horticultural plants. In this experiment, new growth media composed of mixed natural zeolite and peat were prepared for growing tomato plant. To evaluate their quality, a pot experiment was conducted in green house. The treatment were materials of growth media (zeolite and sand), proportion of zeolite or sand and peat (1:0, 2:1, and 1:1) and nitrogen levels (0.2, 0.5, and 1.0 g L-1). The treatment were arranged by factorials and randomized complete design with three replications. The result showed the electrical conductivity (EC) of zeolite-growth media was lower than that of sand-growth media when more inorganic nitrogen present in the media. The contents of NH4-N, cation exchange capacity (CEC), exchangeable bases, and total bases of zeolite-growth media were significantly higher than those of sand-growth media. Additionally, compared to sand-growth media, zeolite-growth media had low bulk density and high water holding capacity (WHC). Addition peat to media significantly increased the WHC and decreased the bulk density, but in the same time, it tended to increase the EC value. Because of the simultaneously good chemical and physical properties, the growth and yield of tomato plant growth in zeolite-growth media were better than those of in sand-growth media. However, plant analysis showed the concentration of N, Mg, P, K, S, Na, media. This indicates more fertilizer should be added to zeolite-culture media. It was concluded that natural zeolite is considered to be a good material for growth media of horticultural plants.