Reclamation of Acidic Dredge Soils with Sewage Sludge and Lime at the Chesapeake and Delaware Canal.

摘要

A field study was conducted to assess the effects of sewage sludge and lime on the revegetation and reclamation of acidic (pH3.0) and infertile dredge soils. Sewage sludge at 100 metric tons/ha (45 tons/acre) and lime at 25 metric tons/ha (10 tons/acre) were applied during the summer of 1974 on a seven hectare site and plowed into the soil to a depth of 20 cm (8 in.). Soils were sampled 20 months later at three depths, 0-20, 20-40, and 40-60 cm (0-8, 8-16 and 16-24 in.) within the sludged and control areas. A total of 29 grass treatments were evaluated and 7 grass types analyzed for mineral composition. At the 0-20-cm soil depth, sewage sludge plus lime increased pH, cation exchange capacity, exchangeable calcium and magnesium, organic carbon, and total, organic and plant available phosphorus. Exchangeable potassium and sodium were unchanged. Below 20-cm, concentrations of plant-available phosphorus and soil pH were similar to control soils, indicating a possible restriction to deep rooting of plants. Applications of sewage sludge appreciably increased the levels of total and extractable metals in the 0-20 cm soil layer and Ca and Mg in the two lower soil depths as well. A large percentage of the Zn, Cr, Pb and Hg applied to the soil was in a form not available to plants, while approximately 50% of the Ni and Cd applied was available. Good seed germination and seedling vigor were evident for all grasses.