Clay Mineralogy of Selected North Alabama Soils.

Kaolinite, halloysite, quartz, and a less well-identified 14 Å clay mineral are common components of soils of the Bankhead National Forest in northwestern Alabama. Soils of the forest are predominantly Typic Hapludults of the Sipsey soil series. The 14 Å clay mineral has characteristics that point to the presence of vermiculites, illites, chlorites and /or some alterations of the minerals. Other than the 14 Å peak of the mineral, most of the peaks of this mineral overlap peaks of other minerals. In addition, 14 Å peaks of some K-saturated clay samples collapsed and shifted to 10.2 Å when heated at 500 ºC whereas that was not observed in other samples. Soils used for the study were sampled from the Bankhead National Forest where prescribed burning and logging are routinely carried out to manage the ecosystem. Some of the characteristics of the clay minerals suggest that they were derived from the sandstone parent material and that they have undergone some alteration since deposition. Soil samples collected from burned and unburned locations, prepared and specially treated for specific mineral identification will be analyzed with XRD using a Panalytical X’Pert Pro MPD diffraction system. Proper identification of the mineral is needed in order to determine how much alteration of the mineral is due to normal pedogenesis or the management practice of prescribed burning. Therefore the objectives of this study are two fold: i) characterize the clay mineralogy of the soils, and ii) determine whether or not the clay minerals were altered due to normal weathering or anthropogenic weathering.