Intensive use of soils in small horticultural production units located in periurban areas: effects on the biota

LAURA J. RAIGER IUSTMAN; JOHANNA DI SCHIENA; SILVANA BASACK; DIANA VULLO

San Martin

Simposio; Laura 5th international symposium on environmental biotechnology and Engineering 5ISEBE; 2016

ISEBE

Soil quality and structure are determinant factors for the biodiversity equilibrium in terrestrial ecosystems. As consequence of agricultural production, pesticides and chemical fertilizers are usually introduced in soils, affecting microbial activities. Particularly, small-scale agriculture around large cities (periurban agriculture) is performed by farmers that, in general, have not received adequate training in the use of agrochemicals. Small farm clusters are located in Moreno District, Buenos Aires Metropolitan Area, where horticulture and floriculture have been developed with high crop rotation and intensive use of both pesticides and chemical fertilizers, evidencing serious soil deterioration. In addition, oil by-products were introduced in these soils as consequence of the oily waste overflows from a treatment plant situated in the proximity. The aim of this work was to evaluate the soil quality and the microbial community composition of productive areas with different crop rotation, agrochemical applications and oily waste flooding events to contribute with the development of future soil restoration technologies. Soil samples were taken in spring 2014 and fall 2015 from two farms (Yucra-Y and Severino-S); from the oil waste treatment plant surroundings (WP) and from reference grassland close to the productive plots (R). Physicochemical characterization was performed following standard protocols and the earthworm Eisenia andrei was used asbiomarker. Bacterial diversity and community composition was analyzed by V1-V3 region-16S rRNA gene amplification (Illumina Miseq). S soils were the most deteriorated ones according to the C/N content, low conductivity and total phosphorous present and Eisenia andrei behavioral assay results.. The effect of seasonal flood events occurring in Y soils,was observed in the microbiall diversity. When comparing fall-2015 with spring- 2014 Y soils, Proteobacteria and Spirochaetes relative amounts were increased while Acidobacteria abundances decreased. In other hand, both Y and S soils Bacteroidetes abundance was increased when compared with R , representing the contribution of the anaerobic population mostly from poultry manure, a current fertilizer used by the local farmers. Within Proteobacteria community, enrichment on -Proteobacteria population was detected especially in S soils, which could be related to the metabolic diversity and the selection pressure imposed by xenobiotic presence. 2015 fall-S soils resulted with the lowest diversity (Shannon Index) but highest abundance, while 2015 fall-Y soils showed the highest diversity with lowest abundance. This analysis confirmed the autochthonous microbiota composition alteration derived by the intensive use of these productive soils and will contribute for future soil quality restoration studies.