Abstract

STERREN, María Alejandra; BENINTENDE, Silvia Mercedes; UHRICH, Walter  and  BARBAGELATA, Pedro. Effect of glyphosate application on soil microorganisms in different soil management practices. Cienc. suelo [online]. 2019, vol.37, n.1, pp.66-76. ISSN 1850-2067.

The objective was to evaluate the immediate effect of glyphosate (Gli) application on microbiological variables, in a Vertisol and a Molisol of Entre Ríos, under different land management. For each soil type, we worked with samples from areas with two crop sequences: continuous soybean (assumed as an area under poor management practices) and wheat / soybean-corn (assumed as an area under good management practices). Soil type, management practice and Gli application defined the treatments. Two days after Gli application we evaluated: residual Gli and aminomethylphosphonic acid (AMPA), C microbial biomass (CBM), respiratory activity (AR), metabolic quotient (qCO₂) and hydrolysis of fluorescein diacetate (FDA). A factorial analysis was performed to study Gli application effects according to soil type and management practices and their interactions. Student's T test was used to compare Gli application treatments. Residual Gli after 2 days of application in good management practices, was lower comparing with poor management practices. Residual Gli was associated with the increase of AMPA contents. The AR, measured along 48 hours after herbicide application was inhibited when Gli was applied, except but for the Vertisol under good practices. CBM decreased significantly in treatments with Gli application, except in Vertisol with poor practices. The highest values of qCO₂ were for Molisol with poor practices and Vertisol with good practices and were associated with lower CBM contents, which shows that microbial populations are different as well as their physiological response to the application of Gli. No significant effects of Gli application were found on FDA in the different soils and managements. The results showed that in soils with good management practices the disappearance of Gli is faster than in soils with poor management practices.

Keywords : Biological variables; residuality of glyphosate; soil management practices.