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.