A field study of five coal surface mine sites reclaimed with sewage sludge and one site reclaimed by conventional methods (chemical fertilizer) was conducted to assess the effects of sludge amendments and time on populations of bacteria, fungi, and actinomycetes, and on microbial respiration and organic matter decomposition. The sludge‐amended sites ranged in age from 1 to 5 yr following sludge application at rates of 120 to 134 Mg ha−1 (dry wt. basis). All sites were planted to grass and legume cover. Populations of aerobic heterotrophic bacteria, fungi, and Nitrobacter, and soil respiration rate, were highest on the 1‐yr‐old site due to the high organic matter input. On the four older sites, values decreased, but remained within the ranges reported for undisturbed soils. Actinomycete populations peaked on the 3‐ and 4‐yr‐old sites, while populations of Nitrosomonas were not related to the age of the site. Decomposition rate was lowest on the 1‐yr‐old site, and increased significantly with site age. As measured by microbial populations and activity, ecosystem recovery on the sludge‐amended sites appeared to be occurring at a more rapid rate than on the fertilizer‐amended site, which after 5 yr, exhibited sparse microbial populations and low activity. The microbial populations in the sludge‐amended spoil were not adversely affected by the heavy metals applied in the sludge, when compared with populations of soil microbes reported for undisturbed soils.
Municipal sludge was applied on a deep mine anthracite refuse bank at rates of 80 and 108 dry Mg/ha to facilitate vegetation establishment. A monitoring system was installed to determine the effects of the sludge applications on the quality and growth of the vegetative cover, chemical properties of the soil, and chemical and bacteriological quality of the groundwater.Data collected over a 5-year period indicate that the addition of sludge improved the physical and chemical condition of the black, highly acidic refuse material and promoted establishment and continued growth of a complete vegetative cover. Sludge applications resulted in slight increases in some trace metal concentrations in the surface soil and in the vegetation. However, soil concentrations were within the normal range found in U.S. soils. Vegetation foliar trace metal concentrations were well below plant tolerance levels and no phytotoxicity symptoms were ever observed. In general, the sludge applications had no significant adverse effect on the chemical or bacteriological quality of groundwater.The results indicate that single applications of stabilized municipal sludge, applied at rates up to 108 dry Mg/ha with lime, can be used in an environmentally safe manner to revegetate coal refuse banks in the Appalachian mining region, with a cover that is self-maintaining for the 5-year period mandated under the federal Surface Mining Control and Reclamation Act of 1977.
Abstract. In 1977, digested and dewatered municipal sludge was applied and incorporated in spoil material at a rate of 184 Mg/ha on a 0.4 ha experimental plot on an abandoned strip mine site in Pennsylvania. Data-were collected for a five-year period (1977)(1978)(1979)(1980)(1981) to determine the effects of the sludge application on the quality and growth of the herbaceous vegetation, the chemical properties of the soil, and the chemical quality of groundwater. In 1989, 12 years after sludge application, the site was again resampled to determine the long-term residual effects of the sludge application, Results of the re-evaluation indicated that the single high application of sludge facilitated the rapid development of a vegetative cover which has persisted over the 12 years with no apparent adverse effects on vegetation, soil, or groundwater.
A field study of five coal stripmine sites reclaimed with sewage sludge and one site reclaimed with chemical fertilizer was conducted to determine the effects of sludge amendments and time on dry matter yields, detritus accumulation, root growth, organic matter content, and soil organic C and N content. The reclaimed sites ranged in age from 1 to 5 yr following reclamation with sludge at rates of 120 to 134 Mg ha−1 (dry wt. basis). The fertilizer‐amended site was 5 yr old. All sites were planted in grass and legume cover. On the sludge‐amended sites, yield, detritus, root growth, and organic matter were positively correlated with site age, increasing from the 1‐yr‐old to the 3‐yr‐old site. On the 4‐yr‐old and 5‐yr‐old sites values were greater than or equal to the 2‐yr‐old site, and no indication of site deterioration was evident. Organic C significantly increased from the 1‐yr‐old to the 2‐yr‐old site, and was highest on the 5‐yr‐old site. Total N remained constant on all sites. On the three older sites detritus accumulation and root growth surpassed that of the 5‐yr‐old fertilizer‐amended site. Yield and organic matter content on the four oldest sludge sites surpassed that of the fertilizer‐amended site, and organic C and N content on all sludge sites surpassed that of the fertilizer‐amended site. As measured by these parameters, eventual soil development and ecosystem recovery appear to be accelerated on the sites reclaimed with sludge compared to the fertilizer‐amended site.
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