Morphological characteristics of reconstructed prime farmland soils in western Pennsylvania

The major soil horizons of prime farmlands disturbed by surface mining in the USA must be reconstructed during reclamation in accordance with current federal legislation. Consequently, the topsoil (Ap horizon) and subsoil (B and C horizons) are removed and stockpiled separately during overburden removal activities and are replaced over spoil during reclamation in an attempt to reconstruct the original soil profile and to help maintain soil productivity. This study was conducted to investigate the morphological, physical, and chemical properties of reconstructed mine soils and to identify characteristics of these soils that could limit crop growth. We described and sampled a total of 72, 1- to 2-year-old, reconstructed soil profiles at eight reclaimed surface mines throughout western Pennsylvania. Soil depth over spoil was generally >75 cm with an observed range of 5 cm to >2 m. Well- expressed Ap horizons were observed in nearly all profiles. The structure of the reconstructed subsoils was drastically altered by mining to a structureless and massive condition. Excessively compacted shallow soil layers restricted downward penetration of plant roots within 47% of the soil profiles described. Reconstructed soil horizons that are likely to restrict plant growth included horizons composed of spoil, horizons with >50% rock fragments and excessively compacted soil layers. These restrictive soil horizons were found within 1 m of the surface for 57 of the 72 soil profiles described and within 50 cm for 51% of the soil profiles. Morphological investigations of reconstructed soils could be useful for evaluating reclamation success and soil productivity potential.