Subsoil horizons

Normally, clay in soil is not present as individual particles but is clustered to aggregates that consist wholly of clay or of a mixture of clay and other mineral and/or organic soil material. Mass transport of soil material along cracks and pores, common in cracking soils in regions with alternating wet and dry periods, does not necessarily enrich the subsoil horizons with clay. 

B Subsoil horizon that shows evidence of weathering or illuviation... 

Kaiser, K. Zech, W. (2000a) Sorption of dissolved organic nitrogen by acid subsoil horizons and individual mineral phases. Fur. J. Soil Sci. 51 403-411... 

Kleber, M., Mikutta, R., Torn, M. S., and Jahn, R. (2005). Poorly crystalline mineral phases protect organic matter in acid subsoil horizons. Eur. J. Soil Sci. 56(6), 717-725. 

Figure 14.15. Depth distribution of summed compound classes in soil profiles under Miscan-thus stands. L and Of describe organic litter layers mainly composed of the Miscanthus residues, Ah the humic mineral topsoil, and Bh an argillic subsoil horizon. Samples were taken in the years 1999 and 2000.

Rumpel, C., Eusterhues, K., and Kogel-Knabner, I. (2004b). Location and chemical composition of stabilized organic carbon in topsoil and subsoil horizons of two acid forest soils. Soil Biol. Biochem. 36,177-190. 

Wright, A.J., Baligar, VC. and Wright, S.F. (1988) Estimation of plant-available manganese in acidic subsoil horizons. Commun. Soil Sci. Plant Anal, 19, 643-662. 

Adams, F. and B. L. Moore. 1983. Chemical factors affecting root growth in subsoil horizons of Coastal Plain soils, Soil Sci. Soc. Am. J. 47 99-102. 

A black color in the subsoil can be related to an accumulation of manganese. In arid and semi-arid environments, the influence of soluble salts (e.g., carbonates, sulfates, and chlorides) may also impart a strong influence on soil color. For example, in arid or subhumid regions, surface soils may be white due to evaporation of water and soluble salts. Colors associated with minerals inherited from parent materials may also influence color in horizons that have not been extensively weathered. For instance, light gray or nearly white colors are sometimes inherited from parent material, such as marl or quartz. Parent material, such as basalt, can imprint a black color to the subsoil horizons. Some soil colors associated with soil attributes are listed in Table 14.7. 

In places where there are concerns about buried materials or sources of contamination, ground penetrating radar (GPR) surveys may be helpful in determining the best sampling approach. GPR can also detect coarse textured subsoils and water relationships in soils having these types of horizons. However, there are some limits as to where GPR can be used and the equipment for doing a GPR survey is expensive [3],... 

Subsoil properties vary with the type of water saturation. In aquic moisture regimes the whole horizon is largely reduced throughout in epiaquic regimes, where the water table is perched, the horizon generally remains oxic and is mottled along wide pores... 

Soil often occurs as a series of horizontal layers called soil horizons, shown in Figure 15.7. The deepest horizon, which lies just above solid rock, is the substratum, which is rock just beginning to disintegrate into soil by the action of water that has seeped down to this level. No growing plant material is found in the substratum. Above the substratum is the subsoil, which consists mostly of clay. Only the deepest roots penetrate into the subsoil, which may be up to 1 meter thick. Above the subsoil is the topsoil, which lies on the surface and varies in thickness from a few centimeters to up to 2 meters. The topsoil usually contains sand, silt, and clay in about equal amounts. This is the horizon where the roots of plants absorb most of their nutrients. 

Residual soil, lower (C) horizon (subsoil) a 25 cm layer within a depth range of 50 cm - 200 cm (<2 mm) Humus where present... 

Stream water Stream sediment (mineral sediment) Residual soil, upper horizon (topsoil) 0 - 25 cm without organic layer Residual soil, lower (C) horizon (subsoil) a 25 cm layer within a depth range of 50 cm - 200 cm Soil samples should represent the dominant soil type of the small catchment. W s T C... 

Two different depth related samples will be taken at each site a topsoil sample from 0-25 cm (excluding material from the organic layer where present) and a subsoil sample from a 25 cm thick section within a depth range of 50 - 200 cm (the C soil horizon). The soil sample should represent the dominant... 

B-horizon (subsoil). This layer is an intermediate soil layer characterized by properties of both the A and C-horizons. 

Subsoil Underlying layers (B and C horizons), which cannot usually be modified except by deep excavation (e.g., graves) and drainage... 

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