Phytostabilization of acidic mine tailings with biochar, biosolids, lime, and locally-sourced microbial inoculum: Do amendment mixtures influence plant growth, tailing chemistry, and microbial composition?

Abandoned mine lands present persistent environmental challenges to ecosystems and economies; reclamation an important step for overcoming these challenges. Phytostabilization is an elegant and cost-effective reclamation strategy, however, establishing plants on severely degraded soils is problematic, often requiring soil amendment additions. We evaluated whether amendment mixtures composed of lime, biochar, biosolids, and locally effective microbes (LEM) could alleviate the constraints that hinder phytostabilization success. We hypothesized that 1) plants grown in tailings amended with lime, biochar, and biosolids (LBB) would establish faster and grow larger than plants grown in tailings amended with lime only, and 2) the LEM source would influence microbial community function and structure in amended mine tailings. We conducted a greenhouse study that simulated in situ conditions to measure the influence of LBB-LEM amendment blends on plant growth, plant nutrients, metal concentrations, microbial function, and microbial community structure. Blue wildrye [Elymus glaucus Buckley ssp. Jepsonii (Burtt Davy) Gould] was grown in tailings collected from the Formosa mine site amended with various combinations of LBB-LEM. The above and below ground biomass of plants grown in mine tailings amended with LBB was 3 to 4 times larger than the biomass of plants grown in tailings amended only with lime. Although the LEM addition did not influence immediate plant growth, it did affect nutrient content and altered the rhizosphere community membership. As such, it is not yet clear if LEM-driven alterations in microbial membership will advance mine reclamation strategies by improving long-term growth.

Impact/Purpose

Abandoned mine lands present persistent environmental and economic challenges. Remediation, reclamation and revitalization are important steps for overcoming these challenges. The use of plants through phytostabilization is an elegant and cost-effective reclamation strategy, however, establishing plants on severely degraded contaminated soils can be problematic, and often requires amendments to improve soil/tailing condition and health to facilitate plant establishment and survival. This study evaluated whether amendment mixtures consisting of admixtures of lime, biochar, biosolids, and locally effective microbes (LEM) could alleviate the constraints that hinder phytostabilization success. This research was guided by two hypothesis 1) plants grown in tailings amended with lime, biochar, and biosolids (LBB) would establish faster and grow larger than plants grown in tailings amended with lime only, and 2) the LEM source would influence microbial community function and structure in amended mine tailings. A greenhouse study simulated in situ conditions was used to test these. Blue wildrye [Elymus glaucus Buckley ssp. Jepsonii (Burtt Davy) Gould] was grown in tailings collected from the abandoned Formosa mine (near Riddle, OR) that were amended with various combinations of LBB-LEM. The above- and belowground biomass of plants grown in mine tailings amended with LBB was 3 to 4 times larger than the biomass of plants grown in tailings amended only with lime. Although the LEM addition did not influence immediate plant growth, it did affect nutrient content and altered the rhizosphere community membership. While it is not clear from this study if LEM-driven alterations in microbial community membership advance long-term mine reclamation strategies by improving long-term plant growth as additional studies are needed to definitively prove this. However, if it proves that amendments and LEM do facilitate the long-term reclamation and revitalization goals, then there will be thousands of hectares of degraded or mining impacted soils across the U.S. that will benefit from their use and the resulting phytostablilization.

Citation

Trippe, K., V. Manning, C. Reardon, A. Klein, C. Weidman, T. Ducey, J. Novak, D. Watts, H. Rushmiller, K. Spokas, J. Ippolito, AND Mark G Johnson. Phytostabilization of acidic mine tailings with biochar, biosolids, lime, and locally-sourced microbial inoculum: Do amendment mixtures influence plant growth, tailing chemistry, and microbial composition? Elsevier Science Ltd, New York, NY, 165:103962, (2021). [DOI: 10.1016/j.apsoil.2021.103962]

DOI: Phytostabilization of acidic mine tailings with biochar, biosolids, lime, and locally-sourced microbial inoculum: Do amendment mixtures influence plant growth, tailing chemistry, and microbial composition?