Use of Lysimeters to Evaluate the Atrazine Dynamics in Soil Cultivated With Maize

Abstract

Despite the numerous studies reporting about pesticide interactions in inumerous environmental conditions, there is insufficient information relating their dynamics to the various textural classes of Brazilian soils and, consequently, the environmental problems caused by the use and application of these compounds. In this way, the objective of this study was to evaluate the atrazine dynamics through determination of the surface runoff and percolation in a Red Latosol cultivated with maize, through studies delineated in drainage lysimeter. Applications of atrazine at the recommended doses were performed weekly up to 44 days after emergence of the maize. Rainfall simulations (150 mm) were performed 24 and 48 h after each application, collecting samples of runoff and percolated water at intervals of 5 min. The samples were sent to the laboratory for analysis of physical and chemical attributes and determination of atrazine concentrations by GC-ECD. Concentrations above the maximum values allowed by the regulatory agencies were found in approximately 99.16% of the obtained samples. The presence of atrazine in runoff and percolated water was recorded. Until 30 days after emergence (DAE) of the crop, higher concentrations of the pesticide were observed in the runoff 24 h after application, mainly in the initial collection minutes. In the percolated samples high concentrations of the pesticide were found even with the development of the crop, however, usually being smaller to those observed for surface runoff. There was a good correlation between the GUS (Groundwater Ubiquity Score) index and the GOSS model and the results obtained. It is concluded that there is the possibility of transporting atrazine in surface runoff and percolation in the different phenological stages of the maize crop when submitted to sequential applications and under high precipitation conditions.