[Studies on survival of salmonellae on agricultural areas (author's transl)]

Subsequent to experimental contamination of grass plots, the persistence of Salmonella typhimurium has been investigated under outdoor climatic conditions. The studies showed the following results: -in the usually shaded zones of the blade of grass near the subsoil and in the superficial soil layer itself, the Salmonella could be reisolated over a period of 28-77 days by Salmonella enrichment methods. On the other hand, the indicator bacteria could be reisolated from the apical zone of the blade of grass for only a maximum of 5 days by the same microbiological methods. In general however, regular isolations of Salmonellae were possible for only a third part of the maximal survival time, which could be detected in the actual experiments. -longer periods of sunshine in connection with only few rainfall seemed to reduce the survival times of the indicator bacteria. The results lead to the conclusion, that an interval of 6 weeks between spreading of liquid manure and the first drive to pasture will result in decreased risk of bacterial infection for grazing animals.