Revegetation and Minesoil Development of Coal Refuse Amended with Sewage Sludge and Limestone

Abstract

AbstractA study was conducted at Peabody Coal Company's Will Scarlet Mine in southern Illinois to evaluate the effectiveness of deep incorporation of dried sewage sludge and/or limestone to ameliorate acid coal refuse (gob) for establishment and survival of three forage grasses. Dried sewage sludge and/or limestone were applied at 10 rates throughout the profile of trenches opened (30 or 60 cm) by a cable trencher. Subplots of reed canarygrass (Phalaris arundinacea L.), tall fescue (Festuca arundinacea Schreb.), and redtop (Agrostis alba L.) were established in September 1980. Analysis of soil chemical and physical changes over time indicated that organic matter applied in the sewage sludge decreased by 35% 2 yr after the plots were established, while the proportion of sand‐size water‐stable aggregates increased over the same period. The proportion of large pores increased in the high rate sewage sludge plots over that of lime‐treated plots. Coal refuse pH increased from 2.7 in the unamended gob to 4.4 to 5.2 with all treatments but the two lower lime rates. All treatments maintained grass stands over 4 yr with the exception of the 225 Mg sludge ha−1 plus 45 Mg limestone ha−1 mixture at 60 cm. Reed canarygrass invaded adjacent plots and was more persistent than the other grasses. Mean herbage yield of the grasses exceeded 4.0 Mg ha−1 on all treatments. Tissue accumulation of heavy metals was not a problem. Tissue NO3 levels were considered toxic for ruminants the first 3 yr, but decreased significantly over time. Coal refuse disposal sites can be revegetated without the use of soil cover by application of sewage sludge or limestone.