Soils and hydrology of a wet-sandy catena in East-Central Minnesota

Soil properties are strongly related to the retention and movement of water within the soil system. The purposes of this study were to document the near-surface hydrology of a wetland-upland hillslope on a sandy glacial outwash plain in east-central Minnesota and to describe the patterns of soil morphology with respect to observed hydrology. Water levels, soil temperature, soil-water tension, and redox potential were monitored at seven points along a 41-m hillslope transect composed of Psamments, Aquents, Aquods, and Saprists. In addition to standard field descriptions, particle-size distribution, percentage of organic C, and citrate-dithionate and ammonium-oxalate extractable Fe (Fe_d and Fe_o, respecitively) were determined for profiles at each transect point. During the study period, the 30-yr mean annual precipitation (MAP) was exceeded in 4 of 5 yr. Mean water levels were highest in spring and water levels typically rose from September through May. The depth to redoximorphic features increases with elevation above the peatland and the upper extent of redoximorphic features is 15 to 60 cm above the measured mean water table level. In the upper landscape positions, the redoximorphic features were located 12 cm above the maximum recorded water level. The distribution characteristics of Fe throughout the soil system indicate that Fe has been removed from the upslope soils and reconcentrated in organic-rich horizons in the lower landscape positions. The combination of Fe distribution and the location of redoximorphic features well above the mean water table suggest that the regional water table has been lowered.