Event-based high-resolution monitoring of pesticides at a cash crop site

Pesticides applied in agriculture often infiltrate into the vadose zone, and flushing events due to rainfall and irrigation can enhance their percolation to groundwater. Understanding the transport dynamics and persistence of these substances in soil is essential, as these compounds can contaminate aquifers, and thus threatening groundwater quality.
This study investigates pesticide mobility, sorption and degradation at a cash crop sites within the Hessian Ried, located south of Frankfurt in Germany.

To study the fate of pesticides, two high-resolution monitoring stations were established on agricultural fields. Soil water samples are collected at varying depths (10 cm, 20 cm, 50 cm, 150 cm, and shallow groundwater) using glass suction cups. This depth-resolved sampling approach will provide insights into the movement and persistence of pesticides in the soil and their possible infiltration into the groundwater.  Furthermore, major ions and trace elements concentrations are measured in the unsaturated zone and in groundwater in eight different depths ranging from 2.30 m b.g.l. to 3.35 m b.g.l. Soil water content is measured using a soil water content profile sensor, while groundwater level and temperature are monitored through a 4-meter-deep hand-drilled well.

The findings help understanding the extent of contamination risks, allowing to design better management practices to protect groundwater quality in the region.