The oxygen diffusion rate (ODR) in soil was measured for 0–5 cm depth by the method of Lemon and Erickson (1952) using the platinum micro-electrode. Ten platinum and a reference electrodes were inserted into the soil and electric current was applied in the circuit. The electric current flowing between the electrodes was proportional to the rate of oxygen reduction which in turn is related to the rate of oxygen diffusion to the electrodes. The ODR was calculated from the measured electric current by Eq. (3).