Characterization and Classification of Soils with Spodic Morphology in the Southern Appalachians1
- D. A. Lietzke and
- G. A. McGuire2
Sixteen pedons with varying degrees of spodic morphology were sampled for characterization and classification on upland landforms in three areas of the southern Appalachians. Sites were located on Clingmans Dome and Unaka Mountain, both astride the Tennessee-North Carolina border, and Poor Mountain located in southwestern Virginia. Vegetation is dominately spruce (Picea rubens)-fir (Abies frazieri) with an ericaceous understory. Parent materials are almost exclusively feldspathic-quartzites that were extensively frost shattered during the late Pleistocene and are now being chemically weathered. Coarse fragments that have been softened by chemical weathering cause pronounced tonguing and streaming of organic compounds from the 0 horizons through the E horizon into the Bhs/Bs horizon beneath. This results in highly variable vertical and lateral expression of spodic morphology over very short distances. Soils with few or without coarse fragments had a more typical expression of spodic morphology. High organic C contents of O and A horizons when mixed with underlying E horizons to a depth of 18 cm imparted umbric colors to all pedons. All Bhs/Bs horizons had accumulations of C, Fe, Al, and clay-sized particles. Three of the 16 pedons met all three chemical criteria for spodic horizon determination. The pyrophosphate extractable Al and Fe to clay ratio was the most critical criterion in this study. The clay content, 14 to 35% in Bhs/Bs horizons reduced this ratio to less than the required 0.2. We propose that this Al + Fe to clay ratio be lowered to >0.1 and <0.2 to identify Entic Haplorthods, and >0.2 to recognize Typic Haplorthods in soils with loamy Bhs/Bs horizons. Two chemical field tests differed in their ability to distinguish spodic horizons from other horizons with spodic character.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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