University of Arkansas, Fayetteville Division of Agriculture


While the plant rhizosphere and associated microbial processes have been shown to amplify the degradation rate of chemical residues in soils, phytoremediation can be a slow process. The objective of this greenhouse study was to determine if the addition of biosolids as an organic soil amendment would enhance growth of plants in oil-contaminated soil and thus potentially increase effectiveness of phytoremediation. Pearl millet (Pennisetum glaucum (L.) R. Br.) or sudangrass (Sorghum sudanense (Piper) Stapf (Piper)) was grown in a Captina silt loam (finesilty, siliceous, mesic Typic Fragiudults) contaminated with 5% crude oil (v/w) and amended with 24 g biosolids/kg soil. Addition of biosolids enhanced oil degradation after 10 weeks as indicated by the lower carbon (C) content in the oil-contaminated soil that was amended with biosolids compared to the C content of the oil-contaminated soil only. The addition of biosolids to the oil-contaminated soil resulted in a significant increase in plant shoot biomass. Pearl millet plus biosolids produced more root biomass, root length, root surface area, and root diameter than sudangrass plus biosolids in the oil-contaminated soil. The addition of biosolids also increased the amount of nitrogen (N) and phosphorus (P) in the soil. The results suggest that the addition of biosolids could increase potential for remediation of oil-contaminated soil.