AbstractThe maintenance or development of plant community diversity in species‐rich wet grasslands has been a focus of water management considerations in the UK for the past 20 years. Much attention has been given to the control of water levels in the ditch systems within these wet grassland systems. In this paper we report measurements of aeration status and water‐table fluctuation made on a peat soil site at Tadham Moor in Somerset, UK, where water management has focused on the maintenance of wet conditions that often result in flooding in winter and wet soil conditions in the spring and summer. Measurement and modelling of the water‐table fluctuation indicates the possibility of variability in the aeration of the root environment and anoxic conditions for much of the winter period and for part of the spring and summer. We have used water content and redox potential measurements to characterize the aeration status of the peat soil. We find that air‐filled porosity is related to water‐table depth in these situations. Redox potentials in the spring were generally found to be low, implying a reducing condition for nitrate and iron. A significant relationship (p < 0·01) between redox potential and water‐table depth exists for data measured at 0·1 m depth, but no relationship could be found for data from 0·4 m depth. Copyright © 2004 John Wiley & Sons, Ltd.