Sandy wet spodosols: Water tables, chemistry, and pedon partitioning

Spodosols are notably difficult to classify in terms of moisture regime, presumably because redox colors are masked by spodic colors, or perhaps because the absence of structure in sandy Spodosols is a hindrance to detection of redox features. Some views of Spodosol pedons as a series of compartments raise the possibility that some portions of the spodic pedon are simply more responsive than others to saturation parameters. This study attempts to determine whether compartmentalization within Spodosol pedons results in differentiation of soil response to saturation and water table fluctuation. Water table and chemical data were compiled from 16 Aquod pedons, Pyrophosphate-extractable Fe and Al, oxalate-extractable Fe and Al, and dithionite-extractable Fe and Al were determined for all soils; organic C was also determined for at least Bh, Bhs, and Bs horizons, and oxalate-extractable Si and the optical density of the oxalate extract (ODOE) were also determined for eight of the pedons, Comparisons of chemical data to saturation and water table fluctuation indicated that spodic horizon chemistry was unresponsive to both saturation duration and water table fluctuation, Chemistry of E horizons was most responsive to water table fluctuation, while Al and Si levels of C horizons were more sensitive to saturation and water table fluctuations. Thus, due to compartmentalization of Spodosol pedons, interpretations of saturation and water table fluctuation can be most effectively made from the chemistry of C and E horizons, respectively. The B horizon chemistry was not a good indicator of saturation duration or of water table fluctuation patterns.