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ARS Home » Pacific West Area » Corvallis, Oregon » Forage Seed and Cereal Research Unit » Research » Publications at this Location » Publication #322484
Title: Gasified grass and wood biochars facilitate plant establishment in acid mine soils

Author
item Phillips, Claire
item Trippe, Kristin
item Whittaker, Gerald
item Griffith, Stephen
item JOHNSON, MARK - Us Environmental Protection Agency (EPA)
item Banowetz, Gary

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/21/2015
Publication Date: 4/1/2016
Citation: Phillips, C.L., Trippe, K.M., Whittaker, G.W., Griffith, S.M., Johnson, M.G., Banowetz, G.M. 2016. Gasified grass and wood biochars facilitate plant establishment in acid mine soils. Journal of Environmental Quality. 45:1013-1020. doi: 10.2134/jeq2015.09.0470.

Interpretive Summary: Water and soils that are adjacent to abandoned mines are typically contaminated with heavy metals. This contamination can move offsite and affect downstream ecosystems. One remediation strategy that has the potential to stabilize soils, stabalize soil, prevent erosion, and reduce surface runoff, involves active revegetation of mine tailings. Although the revegetation of tailings is a promising remediation strategy, heavy metal contamination and acidic soil conditions often limit plant growth and impede revegetation efforts. Biochar is a carbon-rich byproduct of energy production that may have the potential to remediate mine tailings because they decrease soil acidity, immobilize heavy metals, provide plant nutrients, and prevent water runoff. In the current study, we evaluated the ability of wheat to grow in mine tailings that were amended with biochar. Mine tailings were obtained from either the Formosa or the Almeda mines (Oregon, U.S.A.). The biochar used in this study was produced from two locally abundant feedstocks, Kentucky bluegrass (KB) seed remnants or low value timber from conifers (CW). Both KB and CW biochar amendments promoted plant establishment. Formosa tailings required at least 4% biochar and Almeda soil required at least 2% biochar to promote healthy wheat growth. A complimentary experiment indicated that biochar amendment rates =4% were sufficient to simultaneously neutralize the pH of leachate and reduce concentrations of potentially toxic elements (Zn, Cu, Ni, Al) to levels below concern. These findings support the use of gasified biochar amendments to revegetate acid mine soils.

Technical Abstract: Thousands of abandoned mines in the Western U.S. threaten ecosystems, due to high heavy metal concentrations in exposed mine spoils and waters flowing from them. Biochars derived from the pyrolysis or gasification of organic biomass may serve as a valuable soil amendment to revegetate mine sites, due to their ability to increase soil pH, immobilize heavy metals, provide plant nutrients, and increase soil water retention. We evaluated the utility of two biochars, produced by gasification of either Kentucky bluegrass seed screenings (KB, Poa pratensis L.) or mixed conifer wood (CW, dominated by Pseudotsuga menziesii (Mirb.) Franco), to support the growth of plants in tailings from the abandoned Formosa and Almeda Mines, Oregon, U.S.A. To evaluate the potential for plant establishment in mine tailings, wheat (Triticum aestivum L.) was grown in mine tailings amended with biochar at rates ranging from 0-9% by mass. Both KB and CW biochar amendments promoted plant establishment by increasing soil pH, increasing concentrations of macro and micronutrients, and decreasing the bioavailability of heavy metals. Formosa tailings required at least 4% biochar and Almeda soil required at least 2% biochar to promote healthy wheat growth. A complimentary experiment in which we leached mine tailings with simulated precipitation indicated that biochar amendment rates =4% were sufficient to simultaneously neutralize the elution pH and reduce concentrations of potentially toxic elements (Zn, Cu, Ni, Al) to levels below concern. These findings support the use of gasified biochar amendments to revegetate acid mine soils.