Soil Redox Potential and Temperature with Wide Range, 20-90°C.

In recent years, soil sterilization with hot water with the aim of pest control has been carried out in dry field soil. A large amount of CH₄ can be produced by methane-generating bacteria under anaerobic conditions and emitted from the soil surface immediately after adding the hot water. However, dry field soil is generally known for aerobic condition. We thought that the soil might have changed to anaerobic conditions due to the input of a large volume of hot water but studies have shown that it takes about two weeks for a flooded soil to changes from aerobic conditions to anaerobic conditions . The redox potential is used to determine the aerobic or anaerobic conditions in soil. Muto et al. reported about relationship between redox potential and temperature (5 °C~45 °C). However, during hot water sterilization the soil temperature changes from 20°C to 95°C and so this needs further study. Therefore, the purpose of this study was to measure the change of redox potential when the soil temperature rose from 25 °C to 95 °C after the input of hot water. A laboratory Eexperiment was performed where we filled a vinyl chloride pipe with Kanto loamy soil with a bulk density of  0.8g cm^-3. Hot water at 95°C was added to a volume equivalent to  200L m^-2. We measured soil temperature by copper-constantan thermocouple and redox potential by Pt and silver chloride electrodes.Results and coclution will be presented at the meeting.