Fig. 3. Variation in redox potential (E_H) over time for Plot 2R at a depth of 30 cm. Mean and range in E_H is shown as determined from five electrodes at this depth. The data were used to determine the time required for the mean E_H value to fall to where Fe reduction would occur following a saturation event. In this example, the soil had a high mean E_H before December 25, and it required 21 d of saturation before the mean E_H value fell into the level where Fe reduction was expected.