Effect of soil type and temperature on survival of Salmonella enterica in poultry manure‐amended soils

Abstract

The effects of soil type and temperature on the survival of a cocktail of five Salmonella enterica serotypes (Enteritidis, Infantis, Montevideo, Typhimurium and Zanzibar) in manure‐amended soils under controlled laboratory conditions was assessed. Containers of clay loam or sandy soil, unaltered or amended with 2% (w/w) poultry manure, were inoculated with S. enterica (~5 log10 CFU per gram) and held at 5, 21 or 37°C for 6 weeks. Statistical analysis of the persistence of S. enterica identified a significant three‐way interaction between soil type, manure amendment and temperature. Clay loam soils and lower temperatures tended to support S. enterica persistence over 6 weeks with only 1‐ and 2‐log reductions respectively. In contrast, sand and higher temperatures resulted in a 4‐log and either 3‐ to 4‐log reductions respectively. Manure amendment had an overarching effect of reducing die‐off of S. enterica in comparison with unamended soils. This study highlights that a large component of variation of the rate of S. enterica reduction in soils may be attributed to combinations of environmental factors, in particular, soil type and temperature. It further underscores the importance of risk management strategies and industry guidelines based on local data and that reflect the diversity of prevailing horticultural production environments.