Brown podzolic soils

The relatively low leachable Mn concentrations at depth (Fig. 14) are much lower than expected for soils (Wright et al., 1955), which indicates that some of the Mn escapes the sediment and reenters the estuary. Since Mn is fixed below the zone of dissolution, then both the fraction of the deposited Mn that escapes and the rate of escape may be estimated. If the Mn concentration associated with incoming soil particles is taken to be within the range reported for similar gray-brown podzolic soils (800 200 fjLg/gm), then the concentration below 30 cm in Fig. 14 may be used to estimate the fraction lost ... 

Lyford, W. H. (1963). Importance of ants to brown podzolic soil genesis in New England. Harvard Forest Paper No. 7. Harvard Univ., Harvard Forest, Petersham, Massachusetts 01366. 

Analyses of clay skins removed from peds in the Ba-horizon of a gray-brown podzolic soil from Wisconsin were made by Buol and Hole (1959,1961). A portion of these data, as well as a similar analysis of the entire Ba-horizon, are shown in Table 16.1. These analyses show that the clay skins were much higher in N, C, free Fe, P and Mn than was the bulk sample. Microscopic thin-sections of the clay skins showed a range of thickness from 0.016 to 1 mm. A mean cross section with five distinct layers was 0.079 mm thick. In some cases clay skins were embedded in aggregates and lined both the root channels and the roots. In the upper part of the B-horizon the clay skins were thicker and more numerous than in the lower B-horizon. Apparently organic matter plays an important role in their synthesis. 

SOME PROPERTIES OF THE B3 HORIZON AND ITS CLAY SKINS IN A GRAY-BROWN PODZOLIC SOIL, OCKLEY SILT LOAM (from BUOL and HOLE, 1959)... 

Physical, chemical and mineralogical properties of brown podzolic soils in southern... 

Tamura, T., 1952. Properties of brown podzolic soils in southern New England. Paxton and Merriman series. Soil Sci. 81 287. 

Wurman, E., 1960. Mineralogical study of grey-brown podzolic soil in Wisconsin derived from glauconitic sandstone. Soil Sci. 89 38. 

Joffe, J. S., 1940. Lysimeter studies. IV. Movement of anions through the profile of a grey brown podzolic soil. Soil Sci. 50 57. 

McCaleb, S. B., 1954. Profile studies of normal soils of New York. IV. Mineralogical properties of the gray-brown podzolic-brown podzolic soil sequence. Soil Sci. 77 319. 

It is somewhat surprising that so few Rn emanation power studies have been carried out on soils. The study by Delwiche (1958) on Rn release from "Great World Soil Groups" gives relative emanation powers for all but one soil. His results show clearly that the more highly weathered soils emanate more Rn and that the clay intervals emanate more than the silty and sandy intervals. Red podzolic, lateritic podzolic and solodic soils emanate the most and desert soils and western brown forest soils the least. Quantified emanation powers for soils and stream sediments are shown in Table 11-XII. 

Based on the mineralogy controlling weathering and soil development, sensitivity of ecosystem to acid deposition is assessed with a comprehensive consideration on the effect of temperature, soil texture, land use and precipitation. The results show that the most sensitive area to acid deposition in China is Podzolic soil zone in the Northeast, then followed by Latosol, Dark Brown Forest soil and Black soil zones. The less sensitive area is Ferralsol and Yellow-Brown Earth zone in the Southeast, and the least sensitive areas are mainly referred to as Xerosol zone in the Northwest,... 

Studies in Kentucky have shown that soils derived from the same parent rock, a black fissle shale of Devonian age, can differ greatly in their Mo concentrations (Massey and Lowe, 1961). For example, soils from the Colyer series classed as lithosols, which are shallow, with deep broken topography, contain much higher amounts of Mo than do the red-yellow and gray-brown podzolic intergrade soils that have gentle slopes and are moderately well drained. Some soils in the Colyer series, upon liming, produce Mo concentrations in alfalfa that are toxic to livestock (Massey and Lowe, 1961). 

The most typical podzols are usually those formed under coniferous forests less typical are the podzol-like soils formed chiefly under deciduous forests or in a warm climate. In many areas of the United States these two types of vegetation occur in mixture and the resulting soil shows characteristics that are intermediate between the two. In other cases, where man has interfered with nature, deciduous trees may follow coniferous ones, or the reverse. The podzol-like soils are commonly referred to as either gray-brown forest soils of the Temperate Zone or red and yellow podzolic soils of the warmer regions. 

Forest soils may, for the purpose of this discussion, be divided into brown forest soils and those that are more typically podzolic. In general, the brown forest soils are those formed under predominantly deciduous vegetation and are either neutral or only slightly acid. The true podzols are formed under predominantly evergreen softwood vegetation and are often very acid. 

A typical podzol is formed under a heavy layer of organic debris consisting chiefly of needles, cones, dead twigs and branches derived from the heavy stand of coniferous trees that may have been there for many years, usually centuries (see Chapter 7). These organic residues are low in bases, unsuitable as foods for earthworms, and are resistant to decay. The result is the accumulation of a duff or mor layer, often several inches thick. The natural cycle of removal and return of soil bases, so characteristic in brown forest soils, occurs to only a minor extent. 

The occurrence of clay minerals in the great soil groups has been reviewed (Jackson [1959], Grim [1968], Millot [1970]). The abundance and frequently even the predominance of micaceous minerals in the clay fraction of numerous soil types have been confirmed by these articles. Micas and their degraded forms (illite, hydrous mica, mixed-layer minerals with micaceous components) were found to prevail in the clay fraction of arctic raw soils, brown earth s, prairie soils, chernozems, chestnut soils, syrozem, alkali soils, intrazonal mountain soils, and different azonal soils. Remarkable contents of illite have also been observed in the clay fractions of gray-brown, gray, red, and red-yellow podzolic soils. 

Soils of the brown podzolic group have been studied by Rolfe and Jeffries [1953] in central New York State. Here the mica weathers to give a 14 A mineral. Some chlorite appears in the initial stage of weathering. Hydrated mica is dominant at the surface, but decreases with... 

Wurman [1960] has studied soils of the grey-brown podzolic group in Wisconsin that are derived from glauconitic sandstone. He finds mica interstratified with minerals, giving either 14 or 17.8 A reflections after glycerol treatment, i.e., of the types that would be classified, respectively, as vermiculitic and montmorillonitic. The degree of interstratification increases toward the surface. When the potassium contact reaches two-thirds of the potassium content at depth, no significant amounts of pure vermiculite or montmorillonite appear. 

In a later study of layer silicates from soils of northern Wisconsin, Whittig and Jackson [1954] have found that two soils from this region, the Omega loamy sand of the Brown Podzolic group and the Ahmeek loam of the Brown Forest group showed considerable... 

The formation of chloritic interstratified clay minerals in soils by weathering has been studied in detail by Tamura [1955], in the case of a series of New England soils. The Paxton fine sandy loam (Brown Podzolic group) was selected for detailed study. This soil contains randomly interstratified illite-vermiculite systems, giving rise to 001/001 spacings in the range... 

Cady, J. G., 1941. Soil analysis significant in forest soils investigations and methods of determination 3-some mineralogical characteristics of podzol and brown podzolic forest soil profiles. Soil Sci. Soc. Am. Proc. 5 352. 

Except for the top soil where the colour caused by Fe oxides is often masked by hu-mics, most of the soil profile receives its brown, yellow or red colour from Fe oxides (Bigham Ciolkosz, 1993). Because this is so obvious to the naked eye, soils have been named according to colour in most national classification systems, e. g. red-yellow podzols (USA), sol ochreux (France), Braunerde (Germany), krasnozem (Russia), terra rossa (Italy), and even the current modern international systems (U.S. Soil Taxonomy system and World Reference Base for Soil Resources, WRB) use colour connotations such as Rhodic (red) and Xanthic (yellow). 

Figure 11.11 Canonical variate plots showing increases in discrimination among three visually similar topsoils as soil attributes (analyses) are combined. A is a cultivated podzol/improved pasture B is a brown earth/improved pasture and C is a brown earth/seminatural grassland. Four replicate values sampled 4 m apart plus 90% confidence ellipses.

The chemical composition of the bedrock influences the above lying soil and plant cover in the same manner as in the rock-water system. In Central Europe, soils formed on silicate rocks show a typical progressive evolution from regosols through brown soils to podzols with soil pH values below 6.5. Such a typical series from the Alps was described by Huber (1997). 

Podzol-like soils formed in deciduous forests, where there is less resistant surface organic debris, are much less extracted. Deciduous trees assimilate more soil bases from the subsoil than do coniferous trees, and since the leaves decay more readily there is a constant return of bases from the subsoil to the surface, thereby offsetting in part the downward movement in the drainage. These podzol-like soils may have no bleached layer and much less distinct horizons than the true podzols. They are less acid, more fertile than the typical well-developed podzol, and the organic matter is more mixed with the soil mass. Typical podzols have little or no granular structure, whereas the gray-brown soils often have a fairly well-developed crumb structure. 

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