Greenhouse Evaluation of Solum and Substratum Materials in the Southern Illinois Coal Field: I. Forage Crops

Abstract

Abstract More than 75% of the surface‐mined coal in Illinois is produced in southern counties, where soils have a very strongly acid and nutrient‐deficient subsoil that limits root penetration and water availability. Slightly acid (pH 6.2) C 1 ‐material and mildly alkaline glacial till (pH 7.5) overburden strata are readily available in these coal fields, and could be used in post‐mining soil construction. Our objective is to identify overburden materials that can be used as an alternative to the very strongly acid (pH 4.7) subsoil. This study compared the growth of three forage test crops on representative Weir silt loam topsoil (Ap) and subsoil (B 2 ), with deeper C 1 ‐material (B 3 and C 1 strata), and Illinoian glacial till (IIIC stratum). All of the overburden materials studied significantly responded to lime and fertilizer with topsoil supporting the best plant growth without amendment. The very strongly acid subsoil was shown to be inferior to the leached C 1 ‐material found immediately below it. Amendment with high levels of lime and fertilizer was required to achieve maximum productivity on the native subsoil. Blending the subsoil with the C 1 ‐material was shown to be a viable alternative to liming it, and provided a more desirable texture as well.