Imazapic interaction and mobility in soil cultivated with sugarcane in northeast Brazil

Fernando Xavier de Assis,Valmir Felix de Lima,João Paulo Siqueira da Silva,Bruno Toríbio de Lima Xavier,André Maciel Netto

doi:10.1590/2318-0331.262120210007

Abstract

ABSTRACT In the plantation of sugarcane, Imazapic has used pre- or post-emergence, alone or in combination with other herbicides. When applied to the soil in pre-emergence, Imazapic can undergo the sorption, leaching and/or degradation processes due to physical, chemical and biological effects, besides being absorbed by weeds. The objective of this work was to evaluate the interaction and mobility of the Imazapic herbicide in the soil where the soil columns with a dystrophic Yellow Ultisol (YUd) and a dystrophic Red-Yellow Oxisol (RYOd) from northeastern Brazil were used. The higher adsorption potential of the RYOd is associated with higher clay content, higher Fed and Feo concentrations, and soil acidic pH. The CDE – 2 sorption sites model adequately represented the experimental data from the Imazapic breakthrough curves to the RYOd and YUd soils. From the Kd partition coefficients for RYOd and YUd, high values of the GUS index (5.94 and 7.04, respectively) were calculated, confirming the high leaching potential of the Imazapic molecule in these soils.

Highlights

In Brazil, the consumption of pesticides in sugarcane crops corresponds to approximately 13% of the total marketed
Imazapic has a high solubility in water, and when dissolved it has a high contamination capacity of surface and groundwater, both evaluated by the EPA (American Environmental Protection Agency) criteria and by the Groundwater Ubiquity Score (GUS) method (Gonçalves et al, 2013)
According to the values of the physical attributes (Table 2), there is a predominance of the sand fraction in the superficial layer (0-20 cm) of the dystrophic Red-Yellow Oxisol (RYOd) and the dystrophic Yellow Ultisol (YUd), presenting 486 and 854 g kg-1, respectively, and the coarse sand is higher than the fine sand content, mainly in the YUd

Summary

Introduction

In Brazil, the consumption of pesticides in sugarcane crops corresponds to approximately 13% of the total marketed. The herbicides amount to 60% of the total pesticides marketed (Instituto Brasileiro de Geografia e Estatística, 2015). Imazapic is an herbicide belonging to the chemical group of imidazolinones, toxicological class II, of selective control applied in pre and/or post-emergence of plants in crops such as: Peanut (Arachis hypogaea L), Rice (Oryza sativa), Maize (Zea mays), Soybean (Glycine max) and Sugarcane (Saccharum offcinarum) (Cox, 2003). There are studies on the leaching and volatilization of Imazapic in tropical soils in Brazil (Inoue et al, 2014; Monquero et al, 2010; Souza et al, 2020). Studies already carried out are still not enough due to great diversity of soils, climatic, geographical and geological diversity

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Conclusion