Which conditions contribute to increased leaching of pesticides?

Sandy soils and high groundwater levels significantly contribute to the increased leaching of pesticides. Sandy soils are characterized by large particle size and good drainage capabilities, which allow water, along with any dissolved pesticides, to move more quickly through the soil profile. When high groundwater levels are present, there is a reduced capacity for the soil to hold or retain moisture, creating conditions under which water—along with any chemicals it carries—can move rapidly downward, facilitating leaching into groundwater.

In contrast, dry and compacted clay soils, heavy rain on well-drained soils, and overcast sky conditions do not create similar leaching conditions. Compact clay soils tend to retain water and restrict water movement, while heavy rain on well-drained soils may lead to run-off rather than leaching. Overcast conditions also do not directly influence leaching in the way that soil type and groundwater levels do. Understanding these dynamics is crucial for effective pesticide management and minimizing environmental impact.