Utilization of Sewage Sludge for Terrain Stabilization in Cold Regions. Part III

摘要

The authors have conducted a two-year revegetation study to assess the ability of sewage sludge applications with or without supplemental fertilizer to promote plant growth and stabilize sloping soils. The study site was a west-facing, 16 deg slope at CRREL in Hanover, New Hampshire. Eight revegetation treatments and one control were replicated three times. Treatments involved applications of dewatered, anaerobically digested sewage sludge at two rates (20 or 40 tons/acre). The sludge was applied alone or in combination with commercial fertilizers which supplied nitrogen, phosphorus and potassium, or all three nutrients. The seed mixture in the treatments contained four grasses and one legume. The effects of the various treatments were determined through soil loss yields, visual grass ratings and plant yields. Results show that average soil loss from all treatments was within the acceptable limit of one ton/acre per year and was significantly less than that from the untreated controls. Supplementary fertilizers rich in N, P and K or in P and K appear to be slightly more beneficial than those with N alone in the reduction of soil loss. Greater plant yields during the first year were from the treatment with the lower sludge rate and supplemental fertilizer. During the second year, treatments with the high sludge rate were the better producers. Tall fescue and red fescue were the plant species that performed well in all treatments, while birdsfoot trefoil was the dominant species in treatments which did not receive nitrogen fertilizer.