Abstract

The desired vegetation is often difficult to establish in mine soils without proper amendments. In this paper, two coal-mine soils were studied to assess changes of soil quality in response to a range of amendments. Sample A with relatively neutral pH (6.1) was obtained from the top soil at a reclaimed surface-coal-mining site while the other sample B (pH 4.4) from nearby piles of coarse coal refuse. Amendments included zeolite of two grain sizes, flue gas desulfurization gypsum (FGD), flyash, and biosolids at 10% (w/w) rates. Chemical analysis showed that neither soil contained significant amounts of toxic elements except for B and Sr. Lettuce seed germination indicated that original sample A possessed a better quality with 76.7% germination and 7.3 cm shoot length in comparison with soil B having 60% germination and 3.7 cm shoot length. FGD increased the pH of both soils from 6.1 to > 8.0 and from 4.4 to > 6.0, respectively. Moreover, FGD significantly enhanced lettuce germination (83.3%) and seedling growth (6.7 cm) in soil B but did not greatly affect those in soil A. We concluded that soil acidity might be the major chemical constraint inhibiting plant establishment in acidic mine soils and that amendments such as FGD which could increase soil pH up to the neutral level would enhance plant growth in these soils. Biosolids enhanced aggregate stability of both soils with geometric mean diameter increased from antecedent values of 0.90-0.97 mm to 1.2-1.6 mm. Zeolites or flyash did not significantly impact the mine soil quality.

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