Abstract
ABSTRACT: Adjuvants, such as mineral oils, are widely used in the application of herbicides by reducing the drift and evaporation of the droplets and by increasing herbicide uptake by the plant. However, little is known about how mineral oil behaves when in contact with the soil. Thus, the objective of this research was to evaluate the transport of atrazine via leaching with the addition of mineral oil in a soil agricultural under laboratory conditions. To quantify the concentration of the herbicide along the profile of the very clay soil column (30 cm), 14C-atrazine (ring-U-14C) was used with 16,667 Bq of radioactivity per column in volume of 200 mL solution and 0 (control), 1, and 2% mineral oil (v/v) was added in the application volume. Atrazine was applied at the highest commercial dose recommended for sugarcane (4 kg ha-1). After simulation of a precipitation of 200 mm for 48 h, each column was sectioned into six parts of 5 cm and the analytes of each soil sample and the leachate were quantified by liquid scintillation spectrometry. The atrazine remained in the superficial layer of the soil, between 0 and 10 cm of depth, independent of the addition of mineral oil. No atrazine residues were detected in the leachate solution (> 30 cm) in any evaluated treatment. The addition of mineral oil at the time of application of pre-emergence atrazine did not interfere with the transport of this herbicide in the soil profile agricultural via leaching; therefore, the adjuvant may have positive effect only in the herbicide-plant relationship.
Highlights
Atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2.4-diamine) is a selective and systemic herbicide that acts on the inhibition of photosystem II, interfering in the Hill reaction, and its non-cyclic photophosphorylation is associated with the photosynthetic process (Shimabukuro and Swanson, 1969)
Atrazine has already been banned in nine countries plus the European Union, which is comprised of 28 member countries (Pesticide Action Network International, 2017)
Leaching of atrazine in soil profile with addition of mineral oil Figure 1 shows the results of atrazine leaching after application of simulated rainfall in the soil columns
Summary
Atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2.4-diamine) is a selective and systemic herbicide that acts on the inhibition of photosystem II, interfering in the Hill reaction, and its non-cyclic photophosphorylation is associated with the photosynthetic process (Shimabukuro and Swanson, 1969). In Brazil, this herbicide is widely used in agriculture, mainly in sugarcane and maize crops for the control of Eudicotyledonous weeds. In 2016, the country commercialized almost 29,000 ton of the active ingredient, making atrazine the fourth most sold pesticide (IBAMA, 2018). Atrazine has already been banned in nine countries plus the European Union, which is comprised of 28 member countries (Pesticide Action Network International, 2017). Moreira et al (2012) detected the atrazine to surface waters, groundwater (wells) and rain water at levels higher than the maximum established by the National Council of the Environment – CONAMA (Brazil, 2008), which is 2 μg L-1 Due to its physicochemical properties, such as low volatility, high leaching potential and moderate persistence in the soil, the atrazine has high potential as a polluter of water and several toxic effects to organisms (Ghosh and Philip, 2006). Moreira et al (2012) detected the atrazine to surface waters, groundwater (wells) and rain water at levels higher than the maximum established by the National Council of the Environment – CONAMA (Brazil, 2008), which is 2 μg L-1
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