Physicoㆍchemical Properties of Inorganic Materials Currently Used as Root Medium Components for Crop Production in Korean Plant Factories

Inorganic materials were co㎜only used as container media in domestic plant factories. Objective of this research was to secure the information in soil physical and chemical properties of inorganic materials such as vermiculites and perlites. To achieve this, 12 gold and silver vermiculites from China, Zimbabwe, and South Africa and 5 perlites from China were collected based on the marketing grades (MG) in particle sizes and analyzed for determination of their characteristics. The percentage of particles larger than 710 ㎛, in China perlite MG 3~5 mm, China silver vermiculites MG greater than 8 mm and MG 3~8 mm were 99.9%, 99.8%, and 99.7%, respectively, which were much higher than 28.4% in China gold vermiculite MG 0.3~1.0 mm, 14.0% in perlite MG less than 1.0 mm, and 12.6% of Zimbabwe silver vermiculite MG less than 1.0 mm. The container capacities of perlite MG less than 1.0 mm and South Africa silver vermiculite MG 0.25~1.0 mm were 72.0% and 71.1%, respectively. The air space in China silver vermiculite MG 3~8 mm was 49.3% which was higher than other materials tested. However, the China gold and silver vermiculites MG 0.3~1 mm had 3.5% and 2.4% in air space indicating that possible problems could occur in soil aeration when they are used for container media. The percentage of easily available and buffering water of China gold vermiculite MG 0.3~1 mm and perlite MG less than 1.0 mm were the highest among test materials. The ranges of pH and electrical conductivity were 6.36 to 10.7 and 0.032 to 0.393 dSㆍm-¹ in vermiculites and 7.78 to 8.62 and 0.030 to 0.041 dSㆍm-¹ in perlite, respectively. The cation exchange capacity of China silver vermiculite MG 0.3~1 mm were 14.7 cmolㆍkg-¹ that was 10 times as high as 0.34 cmolㆍkg-¹ in perlite MG 1~2.5 mm. The vermiculites had the higher contents of exchangeable cations such as Ca, K, and Na, than those of perlites.