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Supplemental Top - Dressing <br />Despite its manifold benefits, direct place topsoiling often proves <br />logistically impossible in western surface mining due to requisites of <br />mining methods (5). In such cases, stockpiling of salvaged topsoil <br />for later use is unavoidable. One approach to compensate for losses in <br />plant propagule viability and microbiological activity in stored <br />topsoil following its eventual spreading over spoil might be to subse- <br />quently apply a thin layer of freshly salvaged topsoil as a supplemental <br />"top- dressing." This surface - applied fresh topsoil may then serve as a <br />source of both viable plant propagules for enhanced volunteer growth <br />(and resultant diversity), and as an inoculum for soil microorganisms. <br />Since the function of the top- dressed fresh topsoil would be primarily <br />as a source of plant propagules and microorganisms, only limited quan- <br />tities would be required. Therefore, this approach may have particular <br />value and feasibility in situations where availability of fresh - stripped <br />topsoil is low. <br />Although the idea of supplemental top- dressing has been recognized <br />for some time, no specific research on this approach has been conducted. <br />Evaluation of its actual effectiveness, therefore, is obviously impos- <br />sible. It is mentioned here simply as an approach which could poten- <br />tially benefit revegetation and soil development in general, and vege- <br />tation diversity in particular. Hopefully, the principle will be field <br />applied and evaluated in the future to allow determination of its abso- <br />lute value. <br />Multiple -Lift Topsoiling <br />Multiple -lift application of plant growth media over surface spoil <br />may be defined as the process of separate, sequential salvage, handling/ <br />storage and redeposition of discrete vertical zones of earth materials <br />within a topsoil - subsoil profile. Since differentiation of "topsoil" <br />and "subsoil" tends to be somewhat nebulous and inconsistent, for the <br />purposes of the following discussion the broad definitions forwarded by <br />McGinnies (23) and Robbins (40) will be used. "Topsoil" will be <br />defined simply as the uppermost, superior quality earth material salvaged <br />for surficial application, comprising all of the A horizon and frequently <br />all or part of the B and C horizons. "Subsoil" will be defined as that <br />earth material below salvaged topsoil but above parent material, which <br />may sometimes also be salvaged. <br />Separate, specific salvage of subsoil and its deposition below <br />respread topsoil may not be necessary when topsoil volume is sufficiently <br />high and /or when surface spoil possesses acceptable characteristics (40). <br />However, when the above conditions do not exist, the value of salvage <br />and application of a discrete subsoil zone below topsoil is commonly <br />recognized (23), and subsoiling is consequently employed as an edaphic <br />reclamation technique at a number of Northern Great Plains coal mines <br />(e.g., 5). <br />261 <br />