How Far Can Pesticides Spread? A Case Study on No-Tillage Farming Systems and Surrounding Forest Patches

With the growing global concern on pesticide management, the relationship between its environmental recalcitrance, food security and human health has never been more relevant. Pesticides residues are known to cause significant environmental contamination. The present study focused on long-term no-tillage farming systems and subtropical forests in Brazil, where Glyphosate (GLY) has been applied for more than 35 years. GLY and the main breakdown product of glyphosate, aminomethylphosphonic acid (AMPA) were determined by high-performance liquid chromatography coupled with a fluorescence detector. In addition, the presence of carbamates, organochlorines, organophosphates and triazines were also detected. GLY and AMPA were omnipresent in soil samples, reaching values higher than those described for soils previously in the literature. GLY and AMPA were observed respectively at peak concentrations of 66.38 and 26.03 mg/kg soil. GLY was strongly associated with forest soil properties, while AMPA associated with no-tillage soil properties. The texture was a significant factor that contributed to the maximum discrimination of the results since clay and sand contents influence GLY and AMPA retention in soils. This was the first study to report DDT and metabolites in consolidated no-tillage soils in Brazil (a pesticide fully banned 2009). Based on human risk assessment and the potential risk of GLY to local soil communities, this study offers a baseline for future studies that will be crucial to understand the toxicity mechanisms on non-target soil biota.