Changes across artificial E-Bh boundaries formed under simulated fluctuating water tables

Spodosols in the coastal plain of the southeastern USA are mainly restricte d to zones of fluctuating water table, but mechanisms of water table linkag e are not well established, A previous study showed that Aquod-like E and B h horizons could be artificially formed only under simulated fluctuating wa ter table conditions. The present study was conducted to characterize the r edistribution of components during artificial podzolization and to compare the resultant distributions with those of an Aquod adjacent to the Psamment from which column materials were collected. A hypothesis tested is that th e E-Bh formation involves colloidal as well as chemical translocation. Arti ficial E-Bh horizons were generated in three acrylic columns using an appro ximate cycle of 22 h of saturation and 2 h of free drainage. Distilled wate r was introduced from the bottom of columns, and oxalic acid from the top. Boundaries migrated downward at a progressively slower rate, and became inc reasingly abrupt and irregular with time, E horizons consisted mainly of st ripped sand grains; coatings were retained in Bh horizons. Fine materials c ontaining C and Al accumulated in the upper centimeters of the Bh, as docum ented by scanning electron microscopy (SEM) and energy dispersive x-ray ana lysis (EDX), Bulk analyses verified accumulations of C in the Bh and a move ment of Al and crystalline clay from E to Bh. Artificial E-Sh formation ent ailed redistribution of sand grain coatings initially present on sands used in columns, Crystalline as well as noncrystalline clay accumulated in the Bh horizon, supporting the idea that E-Bh formation involved colloidal as w ell as chemical migration. A weatherable-mineral source of Al is not requir ed for the artificial water table-induced formation of E-Bh sequences. Nonc rystalline Al, dissolved in the grain-stripping process, is a likely source of Al in Bh horizons of the region, Distributional trends in artificial E- Bh sequences paralleled those of the natural Aquod.