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counterproductive to restoration of the disturbed area to a level at least equal to the pre - <br />mining capability." <br />The literature strongly suggests that topsoil provides a significant and possibly critical <br />role to a properly functioning ecosystem. The salvage and replacement of topsoil is <br />justifiably necessary in mine land reclamation and the market -value of the organic <br />matter, humates, microbes and nutrients present generally exceed the costs of <br />segregation and handling Subsoil acts nominally as a rooting medium and a reservoir <br />for water and nutrients. In the semi -arid west, subsoil is often a root - restricting zone <br />due to accumulated salts and clays. If this horizon is not physically or chemically <br />restrictive, it functions without providing critical support (DeMent, et al., 1997). In the <br />native environment the B- horizon has undergone some soil development. It is regarded <br />as the zone of accumulation where clays and chemicals leached (eluviation) from the A- <br />horizon build up (iluviation). This horizon typically contains: (a) a concentration of <br />salts, carbonates, and colloidal clays either alone or in combination; (b) has a blocky or <br />prismatic structure, and (c) coatings of iron and aluminum oxides may give it a darker, <br />stronger, or redder color (Soil Survey Staff, 1998; Soil Survey Staff, 1999). Organic <br />matter and root mass is significantly lower in the B- horizon. Microbial and mycorrhizal <br />fungal activity is very low due to an alkaline pH, a significantly reduced organic <br />substrate, and lower oxygen levels caused by higher concentrations of clays and salts <br />and the resulting lower porosity. In many cases the B- horizon is a root - restricting zone <br />because of the high clay content, increased salts and carbonates, and low porosity. The <br />C- horizon is the deepest layer in a soil profile. It consists of loose material or <br />unconsolidated rock that has little soil development and is relatively unaffected by <br />biological activity. However, in many instances the C- horizon may provide a superior <br />rooting medium than the high clay and salt content B- horizon materials. Past mine land <br />reclamation has documented that the mixing of topsoil and subsoil to create a <br />maximum depth of replaced soil provides a suitable plant growth medium for <br />Appendix G 4 07/01/02 <br />