Oxygen is only sparingly soluble in water and diffuses much more slowly through water than through air (Schlesinger, 1997). What little oxygen that is present in saturated soils in the form of dissolved O2 is quickly consumed through metabolic processes. Oxygen is used as terminal electron acceptor via respiration by roots, soil microbes, and soil organisms (Sylvia, 2005), and is lost from the soil system in the form of carbon dioxide (CO2). Heterotrophic respiration may completely deplete oxygen in flooded soils; and these effects may be observed within only a few millimeters of the soil surface (Schlesinger, 1997).