Under what soil conditions are pesticides more likely to leach through soil?

The correct answer highlights that sandy soil, which is characterized by large particle sizes and low water retention capacity, has a higher potential for leaching pesticides, especially when it is low in organic matter. This combination allows water to percolate quickly through the soil profile, effectively transporting pesticides downward towards the groundwater, particularly when the groundwater level is shallow. The lack of organic matter further exacerbates this situation because organic matter typically helps retain moisture and bind with chemicals, reducing their movement.

In contrast, the other scenarios involve conditions that would typically slow down leaching. For example, sandy soil high in organic matter has the potential to retain more moisture and bind pesticides, thereby reducing their movement. Heavy clay soils, whether low or high in organic matter, have small particle sizes that create a denser structure, making it more difficult for water and pesticides to rapidly pass through to the groundwater, particularly when the groundwater is deep.