Aeration status in the root zone of maize in relation to soil water content

The aeration status of a silt loam placed in microcolumns was measured in the maize root zone using an oxygen microelectrode. At soil moisture saturation, the O₂ concentration was found to be zero. Maize evapotranspiration led to a fast increase in O₂ concentration against time (2% O₂ after 2 days, atmospheric concentration after 7 days). Surprisingly, for specified soil moisture levels, no significant O₂ concentration differences were observed between planted and fallow soils. These results are discussed to explain observations on the denitrification process in the root zone of plants.