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Amending metal contaminated mine soil with biochars to sequester metals and improve plant growth cover
Citation:
Novak, J., M. Johnson, J. Ippolito, D. Watts, K. Trippe, AND C. Phillips. Amending metal contaminated mine soil with biochars to sequester metals and improve plant growth cover. Agronomy Society of America and Soil Science Society of America annual meeting, Minneapolis, MN, November 15 - 18, 2015.
Impact/Purpose:
There are numerous mine spoil sites in the U.S. that contain highly acidic, heavy metal-laden soils, which limits establishment of a soil-stabilizing plant cover that reduces wind and water erosion of these soil materials. Biochar may be a suitable soil amendment to reduce toxic metals, improve soil fertility, soil water holding and microbial characteristics, thereby allowing for improved plant cover. Biochars are a solid by-product of pyrolysis in which biomass (e.g., plant and animal wastes) is heated in the absence of oxygen. In this study commercially produced biochar from dairy manure was used, along with other amendments, to treat a mine spoil soil from the Formosa Mine in southern OR. Plant growth on the amended soil was used to determine the efficacy of biochar as an amendment to promote plant growth and development on this acidic, toxic metal-laden soil. Three different crops (rye grass, wheat, and white clover) were planted in the mixtures and crop above- and below-ground biomass was determined. Preliminary results show that soil fertility characteristics were greatly improved with soil amendments, however, there was minimal gain in plant biomass due to the biochar alone. Consequently, for this soil amendments are needed to address soil pH and nutrient limitations as well as reducing toxic metal loads and water holding limitations addressed by the amendment with biochar alone. This research provides experimental evidence that will be useful for Remedial Project Managers and those responsible for remediating metals contaminated soils.
Description:
There are numerous mine spoil sites in the U.S. Pacific Northwest that contain highly acidic, heavy metal-laden soils, which limits establishment of a soil-stabilizing plant cover. Biochars may be a suitable soil amendment to reduce toxic metals, improve soil fertility, soil water holding and microbial characteristics, thereby allowing for improved plant cover. We obtained mine spoil soil from the Formosa Mine site near Riddle, OR and conducted an experiment evaluating a biochars’ ability at improving plant growth. Biochar produced from gasified dairy manure bedding was added at 0, 1, 2 and 3% by weight to pots containing the spoil. Lime, poultry manure and inorganic fertilizer were also added to increase soil pH and nutrient levels. Three different crops (rye grass, wheat, and white clover) were planted in the mixtures and crop above- and below-ground biomass was determined. Preliminary results showed that soil fertility characteristics were greatly improved, however, there was minimal gain in plant biomass due to the biochar. The broad taxonomic classification of microbial communities and soil metal extractions are being conducted to ascertain if this biochar has impacted these additional soil quality characteristics.