Physical and Chemical Properties of Potential Topsoil Substitutes in Kentucky Oil Shale Mining Reclamation
- Judith M. Hower,
- Richard I. Barnhisel * and
- T. C. Hopkins
Because the soils that frequently overlie eastern U.S. oil shale outcrops and near-surface deposits are relatively shallow, acidic, and infertile, use of topsoil substitutes and supplemental materials are anticipated to achieve satisfactory reclamation during surface mining. This study was conducted to determine the effects of weathering on selected overburden strata (the Borden and Bedford Shales) in terms of particle-size distribution, moisture retention character, reactivity, and macronutrient availability. Shale samples were subjected to 40 freeze/thaw cycles in the laboratory to simulate field conditions. Laboratory analyses of “weathered” shales indicate these materials could be used as effective topsoil substitutes in mine reclamation. Shale weathering produced a material in the fine earth fraction that approached residual soils in ability to retain moisture and have low lime requirements. Suggested P amendment of weathered overburden was 75 to 150 kg P ha−1. Availability of K in weathered overburden exceeded levels in native soils and because these values were generally very high, K amendment of overburden materials would not be needed. To confirm these findings in terms of vegetative cover and growth response, the establishment of field test plots is necessary.
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