Use of Raw and Composted Poultry Litter in Lettuce Produced Under Field Conditions: Microbiological Quality and Safety Assessment

PIZZARRO, M.D.; CECCOLI, G.; MUÑOZ, F.F.; FRIZZO, L.S.; DAURELIO, L.D.; BOUZO, C.A.

POULTRY SCIENCE

POULTRY SCIENCE ASSOC INC

Año: 2019 vol. 98 p. 2608 - 2614

0032-5791

Lettuce (Lactuca sativa L.)constitutes one the most important vegetable crops worldwide. As many otheragricultural products, its cultivation requires the use of fertilizers, mainlyas a nitrogen source, to improved yield. The application of nitrogenfertilizers is a common practice that can be costly and may pollute surface andground waters. Poultry litter, either raw or composted, is being applied as aneconomically suitable alternative. However, there is a dearth of informationpertaining to the use of poultry litter on this fresh product safety that isusually consumed as a salad. The aim of this work was to determine themicrobiological quality and the nitrate content in lettuce produced, underfield conditions, using either raw or composted poultry litter, coming from thesame original batch. Two experiments were conducted, in successive years, inthe experimental field of Facultad de Ciencias Agrarias (Universidad Nacionaldel Litoral, Santa Fe, Argentina) to assess the effects of recently extractedpoultry litter (year 2016), that consisted of broiler chicken manure plus ricehusk, or composted for 12 months (year 2017) over the above mentionedparameters. The application amounts were, in both cases: 20 T/ha(T1); 40 T/ha (T2), and no application of manure (T). Increasing the applied quantitiesof poultry litter had also increased the health risk associated to lettuce consumption,due to higher nitrate levels and microbial contamination. However, these risks werereduced by composting the material. Our results showed that lettuce contaminationwith faecal bacteria was mainly due to the use of poultry manure. We also demonstratedthat the number and incidence of pathogens were reduced if properly compostedpoultry manure was applied instead of raw one. In conclusion, increasing the doseof poultry litter applied also increases the health risk in lettuce. Though,when the material is properly composted, its fertilizing capacity is maintained,giving proper yields with lower nitrate levels and microbial contamination byenterobacteria.