Characterizing soil aeration with a platinum microelectrode. II. Response under controlled soil physical conditions

Abstract

Platinum microelectrode currents were measured in glass beads and two soils each at two different moisture contents. Diffusivity was kept constant for each soil at each moisture content but oxygen content was varied by changing the composition of the aerating gas. Results showed that current was strongly dependent on voltage; no plateau appeared in the current-voltage curves, but when comparison was made at constant effective voltage, rather than at constant applied voltage, a linear relation existed between current and oxygen concentration up to 21%. Electrical resistance of the soil was measured to allow comparison at constant effective voltage. Oxygen flux calculated at constant effective voltage, unlike that at constant applied voltage, is characteristic of soil aeration conditions irrespective of other physical properties, provided the moisture content of the soil is sufficiently high for satisfactory operation of the method.