We developed the ozone generation system for soil sterilization. The pyramid-type electrode was effective to reduce breakdown voltage and the ozone concentration can be widely controlled by changing the applied voltage. It is also shown that the screw-type electrode has the advantage of high ozone concentration with high efficiency. The model experiment of ozone diffusion in silica gel was carried out to estimate ozone diffusion phenomena in agricultural soil. The effectiveness of ozone treatment of agricultural soil is demonstrated by reducing soil pathogens. (c) 2005 Elsevier B.V. All rights reserved.