Reconstructing Mine and Agriculturally Disturbed Topsoil

These projects examined differing topsoil treatments to support the reclamation of mined sites and disturbed agricultural areas). They explore the potential of using biochar and humalite (oxidized lignite), alone or in combination with labile organic materials (LOM), to improve subsoil (SS) to reclaim topsoil (TS). Both studies support the combined application of stable and labile organic materials for reconstructing topsoil and underline that no single amendment is universally effective though combinations tailored to soil type and reclamation goals show the most promise.

The study on mined sites found that LOM alone produced the highest early biomass while biochar or humalite and LOM produced biomass statistically equal to native topsoil for clay soils. It also found that high-rate humalite improved CEC, reduced pH and phosphorus, and increased boron (B) in soils and plants. The study in agricultural areas found that LOM (alone or with biochar/humalite) improved microbial biomass but biochar or humalite alone did not significantly improve soil physical properties compared to unamended SS. Additionally, they found that biochar or humalite increased total organic C, but had a limited effect on aggregation and compaction unless combined with LOM.