Nella soils are on hillsides, benches and foot slope. Slopes range from 2 to 60 percent. These soils formed in loamy alluvium or colluvium and in residuum of limestone, sandstone and shale. Mean annual temperature is 60 degrees F., and mean annual precipitation is 54 inches near the type location. These are the competing Allen , Etowah , and Holston series and the Bouldin and Jefferson series.
Bouldin soils are on the sides of mountains and are loamy-skeletal.
Jefferson soils are on the sides of mountains and foot slopes. They are Hapludults and have hues of 10YR or 7.5YR in the Bt horizon. Runoff is medium on gentle slopes and rapid on the steeper slopes. About one-third is in forest consisting chiefly of oaks, hickories, yellow poplar, beech, and shortleaf and Virginia pine. Cleared areas are used chiefly for pasture but a few areas are cropped to tobacco, corn, truck, and small grain.