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Title: ACCUMULATION OF ORGANIC CARBON IN RECLAIMED COAL MINE SOILS OF WYOMING

Author
item STAHL, P - UNIVERSITY OF WYOMING
item ANDERSON, J - UNIVERSITY OF WYOMING
item INGRAM, L - UNIVERSITY OF WYOMING
item Schuman, Gerald
item MUMMEY, D - UNIVERSITY OF WYOMING

Submitted to: American Society for Surface Mining & Reclamation Annual Meeting Proceeding
Publication Type: Proceedings
Publication Acceptance Date: 6/3/2003
Publication Date: 6/3/2003
Citation: STAHL, P.D., ANDERSON, J.D., INGRAM, L.J., SCHUMAN, G.E., MUMMEY, D.L. ACCUMULATION OF ORGANIC CARBON IN RECLAIMED COAL MINE SOILS OF WYOMING. AMERICAN SOCIETY FOR SURFACE MINING & RECLAMATION ANNUAL MEETING PROCEEDING. 2003.

Interpretive Summary: Reclaimed mined lands have considerable potential for carbon storage because the topsoil salvage and mining process degrades the original topsoil through the mixing of several soil horizons and stockpiling which significantly reduces the inherent soil organic carbon level. Revegetation of these lands increases organic matter inputs into the soil system through aboveground plant residues and root material. Field evaluation of several mine sites indicate that the soil organic carbon levels increase rapidly after revegetation and in many cases exceed the levels observed in adjacent native rangelands. However, this rapid increase may be due to the fact that the microbial decomposition is not occurring at the levels observed in the native rangelands, because estimates of microbial biomass in the reclaimed mined lands is only about 60% of that observed in the undisturbed rangeland soils. Further studies will be initiated to assess the microbial activity of these soils and also to evaluate plant residue decomposition. If microbial decomposition is not functioning at normal levels this could result in poor nutrient cycling in these disturbed ecosystems and prevent sustainability of the reclaimed ecosystems.

Technical Abstract: The potential to sequester carbon and increase organic nutrient storage in disturbed soils, such as those reclaimed after surface coal mining, appears to be significant. Quantification of organic carbon accumulation is complicated, however, by the presence of coal and coal dust in these soils. Our preliminary data on organic matter content of reclaimed soils at surface coal mines in Wyoming suggest they are sequestering carbon at a rapid rate. Data from a surface mine reclamation site near Hanna, WY indicate that surface (0-15 cm) soil organic carbon content has increased from a low of 10.9 g C kg-1 soil in 1983 to 18.6 g C kg-1 soil in 1998 and to 20.5 g C kg-1 soil in 2002. Undisturbed soil directly adjacent to the reclaimed site has a mean organic carbon content of 15.1 g kg-1 soil. At a mine near Glenrock, WY, soil organic carbon at a site reclaimed in 1979 increased from an estimated low of 5.8 g C kg-1 soil to a current level of 18.4 g C kg-1 soil. Organic carbon content of undisturbed soils adjacent to the reclaimed area range from 9.9 to 15.7 g C kg-1 soil. In contrast to the elevated organic carbon content, amounts of microbial biomass in reclaimed soils at both mines are lower than in nearby undisturbed soils (ca. 60% or less). We have collected similar data from a number of other surface coal mines in Wyoming. We hypothesize that decomposition rates are slow in reclaimed mine soils due to low microbial activity relative to that in undisturbed soils.