Subsurface Horizon Blending: An Alternative Strategy to B Horizon Replacement for the Construction of Post‐Mine Soils

Abstract

AbstractThis study was initiated to evaluate various combinations of substratum and B horizon materials, as subsurface rooting media. Materials were collected from each solum and substratum horizon to a depth of about 6 m at two surface mine sites. One of the sites was in southern Illinois and had an infertile Darmstadt (Albic Natraqualf) surface soil with a strongly acid (pH 5.2) and natric subsoil. The other was in west central Illinois and had a Sable (Typic Haplaquoll) surface soil which supports high yielding grain crops with proper management.The experiment was conducted in a greenhouse using large plant containers. The test crop, soybean, was germinated in A horizon material, or in a blend of materials containing A horizon, placed over the given surface rooting medium. This procedure was employed in order to simulate field conditions where seeds germinate in topsoil and root into the underlying material. Performance of the test crop was best where A horizon was segregated and replaced over a blend of the next 3 m of material for treatments made from the Darmstadt materials from southern Illinois. It was poorest where A horizon material was replaced over material from the Darmstadt B2 horizon. The other treatments were intermediate in performance between the A/Top 3 m and the A/B2 (subsoil). A similar trend was found with the Sable materials from west central Illinois, but the difference between the best performing treatment, A/Top 3 m, and the poorest, A/B2 (subsoil), was not as marked.