양액재배용 팽연화 왕겨배지의 적정 사용기간 = Durability of the Expanded Rice Hull as a Hydroponic Culture Medium

다국어 초록 (Multilingual Abstract)

In an effort to evaluate the economic value and durability of the expanded rice hull as substrates,changes in the physical and chemical properties of material and plant growth in that substrate werestudied. Using an electron microscope, the structure of used and new expanded rice hull substrate wasexamined. Considerable decomposition was found in the substrate which had been used one to thretimes. Compactness and lowered porosity in the used substrates were probably caused by decomposi-tion. The results of cation analysis showed the possible destruction of cell wall of rice hulls. AbundantCa2+ in the substrates used for two to three times also indicated the possibility of decomposition. Intomato yield compariso, 15.2% more yield of tomato fruit in a new substrates indicated the negativeeffects of decomposition of one-time used substrates. Yield decreased in the substrates used for thretimes. If perlite substrates is used for three years before renewal and the cost of the perlite renewal iscounted, 65.3% saving in the cost will be realized with the use of an expanded rice hull substrate.Another positive effect of the expanded rice hull substrate is the decrease of environmental contami-nation.