Movement of a pesticide from soil surface to groundwater is called?

• A. Runoff
• B. Leaching
• C. Drift
• D. Spills

Answer: (B)

Downward movement of a pesticide from the soil surface into the soil and toward groundwater is leaching, driven by infiltrating water from rainfall or irrigation. As water percolates, it can carry dissolved pesticides through soil pores, with the extent influenced by the chemical’s solubility and how strongly it binds to soil particles, as well as soil texture and organic matter. Heavy rainfall soon after application increases the downward push of water and the potential for leaching. This differs from runoff, which moves pesticides horizontally across the surface to surface water; drift, which carries pesticides through the air during application; and spills, which are accidental releases at the site.