Monday, 7 November 2005
5

Redoximorphic Feature Formation in Soils Subjected to Simulated Wetland Hydrology.

Rosalynd S. Orr and Martin Rabenhorst. University of Maryland, 7522 Creighton Drive, College Park, MD 20742-0001

The rate, nature, and quantity of redoximorphic feature formation in soils can be affected by numerous factors including soil texture, mineralogy, temperature, organic carbon content, and vegetation. To evaluate the effects of soil properties and environmental conditions on hydromorphology, undisturbed soil cores lacking redoximorphic features in the upper part were subjected to simulated hydric conditions for varying lengths of time in greenhouse and field settings over a 96 week period. Water table dynamics were manipulated to mimic seasonal changes in wetland hydrology. Water table levels, temperature, redox potentials, and pH were monitored in all experimental units. Periodically, soil mesocosms were removed from hydric conditions, and all “newly-created” redoximorphic features were documented through careful morphological descriptions. Initial results from the greenhouse and field studies have shown that redoximorphic features may form in relatively short periods of time. After one 16 week hydrologic cycle in the greenhouse, 1 to 2 percent fine, faint concentrations as soft masses of iron have been described in cores with vegetation treatments. After the completion of three simulated hydrologic cycles, greater percentages of fine, distinct iron concentrations have formed, varying based on soil type and vegetation treatment. In the field experiment, soil cores implanted in a natural wetland were extracted after one year. Cores from the field setting were found to possess greater quantities of redoximorphic features than the greenhouse experimental components. It is anticipated that the results of this study will provide insight into the rates of formation of soil redoximorphic features and may also provide assistance in interpreting hydromorphology and hydric status for problem settings in disturbed areas or in wetland restoration.

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