Consider a scenario with a volumetric oxygen concentration at the soil surface of 21% decreasing to 5% 92cm below the surface. The total soil porosity is 0.4 and the volumetric water content is 0.15 . Assume the Marshall's (1959) relationship () with a diffusivity in the air of . Assume no uptake of oxygen and an oxygen concentration of 241 in air with an oxygen content of 21%