Mortality rates of fecal bacteria in subsoil amended with poultry manure

One potential utilization of poultry waste is in the reclamation of surface mine soil. However, little is known about the persistence of fecal bacteria in the buried environments of reclaimed mine soil. A laboratory study was used to determine fecal bacteria mortality during an 8 week incubation in topsoil and subsoil representative of reclaimed surface mines in western Kentucky. Manure loading rates equivalent to 37·5 and 75 Mg ha^-1 were used. Manure loading rates had no effect on mortality rates. Mortality rates were adequately described by a two-stage exponential decay model. The rates for the first 2 weeks of incubation were significantly greater in subsoil than toposil for total coliforms (0·31 log₁₀ cells day^-1 vs 0·20 log₁₀ cells day^-1), fecal coliforms (0·33 log₁₀ cells day^-1 vs 0·22 log₁₀ cells day^-1), and fecal streptococci (0·31 log₁₀ cells day^-1 vs 0·24 log₁₀ cells day^-1). Bacterial cell numbers decreased to, or close to, detection levels (3 colony forming units g^-1 soil) after 8 weeks of incubation. Manure application to this subsoil does not appear to be a greater threat to environmental quality, due to fecal bacteria survival in reclaimed mine soil, than surface application in the same environment.