Influence of agricultural practices on soil bacterial communities structure

FLOCCO, CG; CUADRADO, V; MERINI, LJ; GIULIETTI, AM

Rosario - Santa Fe

Congreso; XLII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (S.A.I.B.).; 2006

In the last decades, the implementation of the no-till system became a widespread agricultural practice in argentinean “Rolling Pampa” region. It implies the use of herbicides, which are an irreplaceable tool for weed control. The objective of this work was to analyze the composition of the bacterial communities of three soils with different histories of crop cultures and herbicides regimes. In this way, PCR-single strand- conformation polymorphism (SSCP) of partial 16S rRNA genes was used as a genetic profiling technique followed by DNA sequencing of the highly abundant or specific bands of each profile. The dendograms obtained revealed a higher degree of similarity between the two soils with pasture, either a wild one (CC soil) or a seeded one (CPDB), regardless the fact that only CPDB soil has a history of herbicides use (2,4-DB). The third soil (CMA) had a smaller degree of similarity with the two pastures, but it can not be said if this is attributable to the different crop use (planted alternatively with maize and soy bean), to the different herbicide regimes (atrazine and glyphosate vs. phenoxy herbicides) or to both factors. Nevertheless, these results suggest that the cultured crop would be the main variable affecting the microbial communities composition in these soils, and that the presence or not of an herbicide treatment would not significantly affect soil biodiversity.