Which of the following factors increases the risk of pesticide leaching?

Poor soil structure significantly increases the risk of pesticide leaching due to the way it affects water movement and retention within the soil. When soil structure is compromised, it can create uneven pore spaces that allow water to move too quickly through the soil profile. This rapid movement can carry pesticides down through the soil more efficiently than it would in soils with a good structure that holds water and nutrients better, slowing down the potential for leaching.

In contrast, high organic matter content tends to improve soil structure and water retention, thus reducing leaching risk. Shallow groundwater may not directly lead to increased leaching risk but rather indicates that there is a higher possibility of contamination for water sources as pesticides can travel quickly through shorter soil layers. Deep sandy soils typically allow water to drain quickly, which can increase leaching; however, the relationship is more pronounced with poor soil structure, as it directly impacts the overall water movement dynamics.