Delineating anthropogenic hydric soils on mine tailing in the Copper Basin, Tennessee for classification and use

The location and extent of hydric soils are of interest to land managers. A soil investigation on a copper mine tailings pond in the Copper Basin, Tennessee, presented an opportunity to study the formation of anthropogenic or disturbed hydric soils. Hydric Soils are important because they are one of three parameters critical in delineating wetlands. The objectives of this study were to: 1) conduct complete soil morphological,chemical, and physical characterization to identify the soils on the mine tailings pond; 2) classify the soils to the family level of soil taxonomy; and 3) use the data obtained in objectives 1 and 2 to delineate the hydric soil fringe around anthropogenic wetlands.

A total of ten pedons were described and sampled according to standard soil survey manual methods. Selected points were sampled with an auger to determine depth to the gleyed layer, color, and depth to the water table. These were used to delineate the hydric soil fringe. Particle size analysis, free iron, hydroxylamine manganese, organic carbon, total elemental analysis, pH, exchangeable bases, cation exchange capacity, KCl exchangeable acidity, neutralization potential, total sulfur, nitrogen, and carbon were the laboratory procedures performed.

Differences in depth to the water table, proximity to wetlands, location on the mine tailings pond, and landscape position accounted for the chemical, physical, and morphological differences in each profile. Depth to the gleyed layer ranged from 8 to 43cm. Textures ranged from fine sands to silts. Because of the sand textures, cation exchange capacities (CEC) were low (<4) in all soil profiles except for soil profile #20.All horizons had a high base saturation (>100%) due to the high calcium concentrations as a result of the calcium carbonate added during the mining process.

Redoximorphic features corresponded to the changing depth to water table. Iron and manganese concentrations corresponded to the fluctuating water table, depth to the water table, and the proximity of soil profiles to wetlands. Tests for ferrous iron reacted positively to alpha, alpha-dipyridyl in horizons above gleyed layers and negatively ingleyed layers indicating ferrous iron was low or removed, especially in those profiles with shallow water tables.

Sites #5, #6, and #7 were classified as Psammaquents. Sites #8, #12, #13, #14,#15, and #16 were classified as Endoaquents. Site #20 was classified as an Epiaquent.ArcView, selected sampling points, and soil physical, chemical, and morphological characterization were successful in delineating the 15.4 ha (38 ac) of hydric soils around anthropogenic wetlands for future land use management.