Biochar Amendments Influence the Microbial Community Dynamics in Mine Soils.

The 76-acre Formosa Mine in Southern Oregon has been designated as a USEPA Superfund site. Formosa was added to the USEPA’s National Priorities List because acid mine drainage has severely degraded 18 miles of river and negatively impacted the local steelhead fishery. Although phytostabilization is one pathway to remediate abandoned mine sites, hostile edaphic conditions, including toxic levels of metals and the extremely low pH <3.0 are a major impediment to plant establishment. At many mine sites, the microbial-mineral interactions spawn a biogeochemical cycle that perpetuates and increases soil acidity. If the fundamental goal is to establish a permanent ground cover, it will ultimately be important to shift the microbial community structure from one dominated by autotrophs to a community that has a diverse heterotrophic demographic. Reports have indicated that biochar application rate can modulate microbial responses. Still, little is known about the dynamics of microbial communities in assisted phytostablization efforts, or if modulating these populations can accelerate plant establishment and/or stabilize favorable edaphic conditions. The purpose of these studies was to assess the microbial community at Formosa and determine the impact of adding biochar directly to mine soils, with and without lime addition. The microbial community was assessed using quantitative and digital PCR assays. The results of our study demonstrate that biochar can influence microbial communities in mine remediation efforts and may help propel the establishment of plant communities.