Measuring the State of Reduction of a Waterlogged Soil

Summary E h and pH measurements and the term r Eh = E h +3 × 2·3 RT/FpH have been tested under simulated field conditions and errors assigned to them. The author considers that, whilst E h measurements in the field may be used to differentiate between reduced and oxidized soils, their error is too large for them to supply more precise information about the state of reduction of a waterlogged soil; he also considers that there is little point in adjusting these measurements for pH change. It is proposed that an estimation of the concentrations of the two states of iron in a waterlogged soil should be used as the basis of a field method for measuring the soil's state of reduction. The results give some support for the argument that the equation image is applicable to waterlogged soils.