Physical and Chemical Properties of Coal Refuse from Southwest Virginia
1992
Stewart, B.R. | Daniels, W.L.
Coal refuse is difficult to reclaim due to high potential acidity, very coarse texture, low water retention, and fertility. This study was undertaken to determine the physical and chemical properties and the reclamation potential of samples from 27 coal refuse piles of varying age. Selected physical and chemical properties varied widely across this sample set. The >2 mm fragment content was 60%, and the average texture of the <2 mm fraction was a sandy loam with 15% clay. The mean water retention difference, (−1.50 to −0.030 MPa), on a whole sample basis was 0.08 kg water/kg refuse. The pH varied from 3.0 to 8.3 due to differences in the amounts and reactivity of pyritic minerals in refuse. Older piles generally had lower pH values than more recent piles. The saturated paste electrical conductivity (EC) was higher in the younger refuse due to active pyrite oxidation. A 5:1 water to soil (w/w) extract shows promise as an effective screen for samples with potentially high EC values. Coal refuse was generally low in available P and B. Total elemental analysis revealed that Si, Al, Fe, and K were the most abundant elements. The physical factor most limiting to plant growth is likely to be low water holding capacity, while low pH was found to be the chemical factor most limiting to plant survival. These findings indicate that some refuse piles may be suitable for direct seeding, but many will require heavy lime and/or organic treatments for successful reclamation. Contribution of Dep. of Crop and Soil Environ. Sciences, Virginia Polytech. Inst. & State Univ., Blacksburg, VA. This research was supported by the Powell River Project, the NSF Graduate Fellowship Program, and the USDI Bureau of Mines, Virginia Mining and Minerals Resources Inst. under contract no. G1184151.
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