Vegetable contamination with lethal microorganisms is a reality. Organic manure has been considered responsible for vegetable contamination in Brazil. The aim of this research was to evaluate the yield and lettuce contamination by Salmonella sp. and fecal coliforms, at 45 °C, grown under organic fertilization. The experimental design was in randomized blocks composed with 6 treatments in five replicates. The treatments were: T1 - Control (no fertilization); T2 - Chemical fertilization; T3 - Chicken manure; T4 - Cattle manure; T5 - Worm manure, and T6 - Organic compost. Fresh weight, dry matter percentage, macro and micronutrients, and microbiological contamination were recorded. The highest lettuce weight was observed in the parcels fertilized with chicken manure (543 g), which differed statistically from the weights observed in the other treatments. On the other hand, no statistical difference was observed in the dry matter percentage among the different treatments, with the exception of the value observed at the organic compost treatment, which was the lowest (3,7%). The soil and organic manure samples were not contaminated by Salmonella sp. and fecal coliforms. Nevertheless, irrigation water and lettuce samples were contaminated by fecal coliforms. There is strong evidence that irrigation water was the main source of lettuce contamination.
Lactuca sativa L; organic manure; production; contamination; fecal coliforms
