Soils of the North Carolina Piedmont were analyzed for permanent and pHdependent charge components of cationexchange capacity. Permanent charge was taken as the summation of exchangeable metal cations, including Al displaced upon leaching with a neutral salt solution; pH dependent charge was regarded as the amount of exchange acidity (BaCl 2 TEA) remaining after neutral salt leaching.Welldeveloped upland soils had small permanent charges and large pH dependent charges. For soils of a given sequence, the permanentcharge/pHdependent charge ratios (B 2 and above) were smallest for the red end member. Deeper horizons often had very large permanent charges, as did the B horizons of some Planosols. Latosolic soils had smaller permanentcharge/pHdependent charge ratios than did RedYellow Podzolics.Permanentcharge components of CEC were countered exclusively by metal cations. In acid soils AI predominated, while Ca and Mg neutralized most of the permanent charge in soils with pH's above 6. There were negligible amounts of electrostaticallybonded H in any soil. Gener ally exchangeable Al increased with depth. Yellow Podzolic and Planosolic soils in particular tended to have large amounts of exchangeable Al in lower horizons.Percentage base saturation concepts are discussed, the conclusion being that a saturation percentage based on permanent charge is preferred.

At two locations in the southern Appalachian Mountains, soils at two slope positions on north‐ and south‐facing landscapes were described, sampled, and analyzed to determine the relative effect of slope aspect and position upon the differentiation of the parent rock into soil profiles. At the southwestern Virginia study area, the parent rocks are highly siliceous sandstone and siltstone, whereas, the parent rock in southwestern North Carolina is a granitic biotite gneiss.Soils developed from the siliceous parent material were very similar in morphological, physical, chemical, and mineralogical properties irrespective of aspect and slope position. In contrast, there was a high degree of soil profile differentiation at the two slope positions and on the two aspects in North Carolina. In addition to differences in morphological and physical properties, there are distinct differences in the clay mineral suites on opposing aspects. Kaolin and the pedogenic 2:1–2:2 intergrade minerals are predominant in the soils of the north‐facing landscapes, whereas, gibbsite is the major clay mineral in the soils of the south‐facing landscape.

Leaf leachates, simulating canopy drip during rainfall, were collected from southern red oak (Quercus falcata var. pagodaefoliz Ell.), live oak (Quercus virginiana Mill.), and longleaf pine (Pinus palustris Mill.), which were the principal tree species growing on soils with spodic horizons on the North Carolina Coastal Plain near Ft. Caswell. The samples of canopy drip were immediately chilled, filtered, and freeze‐dried. From the representative canopy drip sampled it was estimated that approximately 20 kg/ha per year of organic matter could be contributed to the soil from this source. In the laboratory, 139 to 1,480µ moles of Fe or 460 to 1,450µ moles of Al/g of freeze‐dried canopy drip were complexed from nitrate salt solutions depending on the concentration of the leachate solution. This amounts to a possible field mobilization of 0.15–1.53 and 0.22–0.70 kg/ha per year of Fe or Al, respectively.The active components responsible for Fe and Al mobilization were determined to be polyphenols, reducing sugars, and organic acids. Paper chromatograms and reducing‐sugar analyses indicated that the polyphenol and reducing‐sugar contributions to soil as canopy drip were approximately 1 kg and 4kg/ha per year, respectively. Organic acids were not quantitatively determined. Thus, canopy drip was shown to be an important source of mobile soil organic matter for podzolization and other pedogenic processes.

A study of two soil catenas of different age in the middle Coastal Plain of North Carolina compares the micromorphology and composition of fragipan and nonfragipan soils. The two catenas differ principally in that one has bisequal sola and fragipans in the less well‐drained members, whereas the other has thinner sola with well‐developed argillic horizons but no fragipans. Presence of papules, as well as high packing density and proximity indices, indicate that collapse of the soil matrix has caused the high bulk density of the fragipan horizons. The relatively low amounts of clay in fragipan horizons is believed to be a result of the greater susceptibility of clay to translocation and possibly destruction during reduction and removal of the iron. Translocation of this clay is confirmed by the marked increase of illuvial clay bodies, primarily illuviation cutans and grain argillians, in B′2t horizons below the fragipan (A′2gx). Relative to their clay content, fragipan horizons contain more fine clay with infrared absorption bands in the 2.9µ H‐bonded OH region than do nonfragipan horizons. This clay lacks definite crystalline form and is thought to be amorphous. Stable at lower temperatures, the infrared absorption band at 2.9µ is lost along with the fragipan brittleness at 300C. Though of low free iron content, this clay has a high pH dependent charge. Under the low pH conditions (4.5–5.0) found in fragipan horizons, this clay may develop strong hydrogen bonds with quartz and other silicates.

Properties of soils representative of the elevation from 4,500 to 6,600 feet in the Smokies along the North Carolina‐Tennessee border are reported. Mean annual rainfall exceeds 80 inches. Mean air temperatures are: annual 45° to 49°F.; January, 31° to 35°F., July, 59° to 63°F. Parent rock is feldspathic sandstone and conglomerate. These soils can be placed in two groups: (1) lacking A2 horizons with thin A1 and “color B” horizons, and (2) with A2 horizons, Bir horizons, and relatively thick mor layers. Soils of the first group ordinarily occupy well‐drained sites under spruce‐fir forest. Those of the second group occupy less well‐drained sites under heath bald or rhododendron understory of sprucefir, with some indication that they tend to form from more quartzose conglomeratic rock. Soils of the first group are ascribed to the Sol Brun Acide great soil group on the basis of very low base status and high exchangeable Al, C/N levels, lack of relative accumulation of free iron and of layer silicates, and lack of A2 horizons. Second group soils are excluded from the Sol Brun Acide group, due to the presence of A2 horizons, differential iron accumulation, and C/N levels, and are interpreted as Podzols. Possible mechanisms are proposed to account for contrasting properties of the Sol Brun Acide and Podzol soils described, and the anomalous absence of A2 in the Sol Brun Acide of the Smokies. Extreme acid hydrolysis, producing intergradational three‐layer silicates plus kaolinite and gibbsite weathering end products, is postulated for these soils.