Municipal Sludge for Minespoil Reclamation: II. Effects on Organic Matter

Abstract

AbstractA 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.