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Gasified grass and wood biochars facilitate plant establishment in acid mine soils
Citation:
Phillips, C., K. Trippe, G. Whittaker, S. Griffith, M. Johnson, AND G. Banowetz. Gasified grass and wood biochars facilitate plant establishment in acid mine soils. JOURNAL OF ENVIRONMENTAL QUALITY. American Society of Agronomy, MADISON, WI, 45:1013-1020, (2016).
Impact/Purpose:
Often residual heavy metals (e.g., Cu, Zn, Pb) in exposed mine tailings threaten ecosystems that surround thousands of abandoned mines in the U.S. Remediating these soils by adding soil amendments is one way to reestablish native plant communities to reduce wind and water erosion and to be protection of human health and the environment. Biochars derived from the pyrolysis or gasification of biomass may serve as a valuable soil amendment to revegetate mine sites. In this study we evaluated the ability of two biochars, produced by gasification of either Kentucky bluegrass seed screenings (KB) or mixed conifer wood (CW), as a mine soil amendment to support the growth of wheat plants in heavy metal laden mine soils from two abandoned in Oregon. Both KB and CW biochar amendments promoted plant establishment by increasing soil pH, increasing concentrations of macro and micronutrients, and decreasing the solubility of heavy metals. Amending these soils with between 2% to 4% biochar (by weight) was needed to promote healthy wheat growth and reduce the mobility of heavy metals. These findings support the use of gasified biochar amendments to revegetate metal contaminated acid mine soils.
Description:
Heavy metals in exposed mine tailings threaten ecosystems that surround thousands of abandoned mines in the U.S. Biochars derived from the pyrolysis or gasification of biomass may serve as a valuable soil amendment to revegetate mine sites. We evaluated the ability 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 mine spoils 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 tailings amended with biochar at rates ranging from 0-9% (w/w). Both KB and CW biochar amendments promoted plant establishment by increasing soil pH, increasing concentrations of macro and micronutrients, and decreasing the solubility 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 mine spoils were leached with simulated precipitation indicated that biochar amendment rates ≥4% were sufficient to neutralize the elution pH and reduce concentrations of potentially toxic elements (Zn, Cu, Ni, Al) to levels near or below concern. These findings support the use of gasified biochar amendments to revegetate acid mine soils.
