Persistence of Herbicides (Glyphosate) Residues in Soil and Tea Leaves: Dambetenna Estates, Sri Lanka

Abstract

Many different herbicides have been suggested to control weeds in tea fields. Among them, glyphosate has become a popular herbicide among farmers because it effectively controls a wide range of weeds. Glyphosate residues in the environment and on plants have increased as a result of its widespread use. Thus, the study aimed to determine the persistence of glyphosate in tea leaves and tea soils in herbicide-applied and herbicidefree tea plantation plots in Dambetenna Estates, Sri Lanka. Glyphosate residue analysis was carried out using the Liquid Chromatography/ Tandem Mass Spectrometry (Triple Quadruple) detection method after sample preparation was carried out using solvent extraction methods. The results showed that glyphosate was detected in tea leaves of glyphosate-applied plots. However, glyphosate was not detected in the tea leaves of the glyphosate-free plots. Glyphosate was detected in soils of both glyphosate-applied and glyphosate-free plots. The mean glyphosate concentration of soils in the glyphosateapplied plot was 5.05 ± 1.09 mg/kg while the reading for soils in the glyphosate-free plot was 2.93±0.14 mg/kg. Further, results revealed that the glyphosate concentration of soils in the glyphosate-applied plot is significantly higher (p = 0.03) than in the glyphosate-free plots. Glyphosate was applied in Dambatenna Tea Estate in accordance with prescribed doses, and levels found in tea leaves were 0.5 mg/kg, which is below the environmental protection agency’s suggested maximum permitted limits. Overall, these findings suggest that the use of glyphosate in tea fields can lead to its accumulation in tea soil and tea leaves.