Behaviors of Greenhouse Gasses in Soil and Their Fluxes At the Soil Surface After Soil Sterilization with Hot Water.

Previously, methyl bromide has been used for soil sterilization. However, it was reported that methyl bromide was thought to deplete the ozone layer. Using hot water for soil sterilization has been popular in Japan as an alternative for using methyl bromide. However it was reported soil sterilization with hot water enhanced the production of greenhouse gasses (CH4, CO2, N2O). Although, the effects of soil sterilization with hot water on greenhouse gasses aren�ft well known. In this study, we investigated the dynamics of greenhouse gasses after soil sterilization with hot water. An experiment was carried out in the plastic greenhouse in Kanagawa Agricultural Technology Center in central Japan. An experimental field carried was divided into two parts for hot water application and tap water application. Hot water (95��) and tap water (25��) were separately sprayed the total volume of water applied for each treatment was 220 L/m2 for 3h on August 12, 2011 with perforated tube. Gas fluxes (CH4, CO2 and N2O) at the surface were measured using the closed tin chambers (14.4 cm radius, 23.5 cm high). Gas concentrations (CH4, CO2 and N2O) in soil were measured 5, 10, 20, 30, 40, 60, 80 and 100 cm deep, with silicon tubing gas samplers (100 cm long, 4 mm inner diameter, 20 mm thick). Concentrations of those samples were analyzed with a GC equipped with FID and ECD. Immediately after the sterilization with hot water, we observed the biggest CH4 and CO2 fluxes at the soil surface, and CO2 and N2O concentrations in soil.