Development of Bermuda grass ( Cynodon dactylon ) seedlings in the diesel-contaminated soil

The development of Bermuda grass seedlings in diesel-contaminated soil was appraised at the concentrations from 0 to 40 mg TPH/g soil (TPH: total petroleum hydrocarbons). The seedlings emerged out of the soil one week after the planting of seeds that remained unchanged over the range of concentrations tested. The seedlings grew at a reduced rate during the six-week period when tested at 10 mg TPH/g soil without triggering additional removal of diesel. The adverse effects of diesel appeared at the concentration ≥ 20 mg TPH/g soil. Sporolactobacillus sp., Prevotella sp., and Clostridium sp. were effective degraders of hydrocarbons with 1 to 6 carbons per molecule, but their additions neither increase nor accelerate the development of seedlings. Hydrocarbons with ≥ 7 carbon atoms per molecule were likely to remain in the bacteria-treated soil, and the impacts of these hydrocarbons on the seedlings emerged at ≥ 4 mg TPH/g soil. Soil pH at 7.2 to 7.4 was adequate.