Transport and Distribution of Salmonella enterica Serovar Typhimurium in Loamy and Sandy Soil Monoliths with Applied Liquid Manure

A leaching experiment, where liquid manure spiked with Salmonella enterica serovar Typhimurium (Tet+) DSM554 was applied to soil surfaces, was conducted on intact soil monoliths (60 cm in diameter and 100 cm long). A total of 6.5 × 1010 CFU was applied to each column. We found that Salmonella serovar Typhimurium could be transported to a 1-m depth in loamy soil at concentrations reaching 1.3 × 105 CFU/ml of leachate. The test strain was found in concentrations ranging from 300 to 1.35 cells/ml in loamy soil throughout the 27 days of the experiment, while concentrations below 20 cells/ml were sporadically detected in the leachates from sandy monoliths. Real-time PCR targeting invA DNA showed a clear correspondence between the total and culturable numbers of cells in the leachate, indicating that most cells leached were viable. On day 28, distribution of Salmonella serovar Typhimurium at five depths in the four monoliths was determined. The highest recovery rate, ranging from 1.5% to 3.8% of the total applied inoculum, was found in the top 0.2 m.