Measurements of aeration in waterlogged soils: some improvements of techniques and their application to experiments using lysimeters

Summary The techniques of measuring oxygen concentrations, oxygen flux and redox potential have been adapted for use in lysimeters. The accuracy and precision of the measurements have been improved, as well as their convenience for use in the limited soil volume of lysimeters. Concentrations of dissolved and gaseous oxygen are measured with a membrane covered polarographic electrode. The analysis is made on samples of air or solution carefully extracted from collection vessels permanently in the soil. Oxygen flux is measured with bare platinum electrodes. Careful choice is made of effective voltage for the measurement of equilibrium oxygen related currents. Redox potential is measured by the same platinum electrode and the reproducibility of measurements from permanently installed electrodes was assessed. The effect of soil structure upon the three kinds of measurement was seen and attributed to differences between the volumes of soil sampled by the different instruments.