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EFFECT OF INTENSIVE USE OF SOILS IN SMALL HORTICULTURAL PRODUCTION UNITS OF MORENO DISTRICT, BUENOS AIRES METROPOLITAN AREALaura J. Raiger Iustman1.3 , Johanna Di Schiena2, Silvana Basack2, Diana Vullo1.21: Dpto Quimica Biologica, FCEyN- UBA. 2: Area Quimica, Instituto de Ciencias, Universidad Nacional de General Sarmiento. 3: IQUIBICEN-CONICETSmall-scale agriculture around large cities (periurban agriculture) is performed by farmers that, in general, have not received adequate training in the use of agrochemicals and currently count with few economical resources. This kind of agriculture presents problems that differ from extensive production causing a strong environmental impact not only by the intensive use of the land, but also by the farming practices applied. The aim of this work is to study the effect of this horticultural practice by monitoring the bacteria community of a strawberry production soil (SS) and comparing with a non-productive soil (a grassland close to the productive plots but fallow for at least 20 years, RS), located in the same farm belonging to Cuartel V, Moreno, Buenos Aires Metropolitan Area.Both soils were analyzed after collecting in 2014 spring several samples of 5 cm of soil using a clean metal punch, obtaining a composite soil of each. The applied pesticides in SS as declared by the farmer were Decis Forte (Deltamethrin), Vertimec (Abamectin) and Rovral 50 WP (Iprodione).Chemical analysis was performed for an integral characterization of the samples. SS showed less conductivity, total carbon, organic matter, and inorganic P content than the reference soil RS. On the other hand, humidity and copper content was higher in the productive soil SS compared to RS. Finally, chlorpyrifos was also found in the strawberry production soil, probably consequence of a previous application on another crop of the same plot.To analyze bacterial diversity, total DNA of both composite samples was extracted using Power soil isolation kit (MoBio) and V1-V3 region of 16S rRNA gene was sequenced by 454 pirosequenciation (Chunlab-Korea). Results showed that bacterial abundance and diversity in SS was higher than in the RS (OTUs number 2527 and 1769 respectively, Shannon index 7.268 and 6.845 respectively). Taxonomically, the class in the SS particularly increased was -Proteobacteria, while in RS was -Proteobacteria. Interestingly, another difference was observed: anaerobic bacteria like Anaeronilales, Clostridiales, Desulfomonadales were found in SS but not in the RS perhaps correlated to the addition of poultry manure, a current practice implemented by the local farmers. As conclusion, the horticultural soil SS showed several alterations in both composition and microbiota, perhaps due to the intensive use in conjunction with the addition of a wide spectrum of agrochemicals. SS became less aerobic, promoting the development of the anaerobic taxa found and, on the other hand, this polluted soil evidenced an increase on -Proteobacteria population, which could be related to -regarding their metabolic diversity- the xenobiotic biodegradation.