Resumo

STERREN, María A; UHRICH, Walter  e  BENINTENDE, Silvia. Residualidad de glifosato en suelos de Entre Ríos y su efecto sobre los microorganismos del suelo. Ecol. austral [online]. 2016, vol.26, n.3, pp.246-255. ISSN 1667-782X.

Glyphosate is a broad-spectrum, not selective, post-emergent herbicide, widely used in agriculture, but we do not yet know its impacts on soil microbial community. The objective of this work was to evaluate the effect of residual of glyphosate on soil biological variables in Molisol and Vertisol soils of Entre Ríos at 2 and 28 days after application, under laboratory conditions. For this, soil samples were incubated at 25 °C with application of glyphosate at a dose of 2.14 L of active ingredient/ha. The biological evaluated variables were respiratory activity (AR), microbial biomass carbon (CBM), metabolic quotient (qCO₂) and nitrogen mineralization potential by anaerobic incubations (PMN-IA). Residuality of glyphosate and aminomethylphosphonic acid (AMPA) were also quantified. To evaluate the interaction between treatment and soil was performed with an factor analysis (ANOVA) for CBM and PMN-IA. The results showed that glyphosate had a low residuality in both soils, reducing its concentration to 28 days of application. However, the contents of AMPA were high throughout the study period in both soils. AR, CBM and PMN-IA increased in those soils with application of glyphosate, which showed that microorganisms showed an enzymatic system to degradate it and were encouraged by a source of labile C. The values of qCO₂ in soils with herbicide application showed changes in the physiology of microorganisms and at 28 days in the Vertisol was associated with higher contents of CBM which presupposes that there were different microbial groups. This work showed that herbicide application impacted differently on the two soils. In Molisol microbial populations were unafected and in Vertisol the contents of C of microbial populations were increased and associated with greater amount of residual herbicide.

Palavras-chave : Glyphosate; Vertisol; Biological variables; Microbial biomass carbon; Metabolic quotient; Residual effects.

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