Leaching refers to:

• A. Movement over the surface
• B. Movement through soil
• C. Volatilization
• D. Degradation

Answer: (B)

Leaching is the downward movement of water and dissolved pesticides through the soil profile. When rain or irrigation soaks into the ground, soluble chemicals can be carried with percolating water deeper into the soil, potentially reaching groundwater. This process depends on how soluble the pesticide is and how strongly it sticks to soil particles; soils that are sandy or low in organic matter allow more downward movement, while stronger adsorption slows it. Leaching is different from surface movement (runoff), which carries chemicals across the soil surface, volatilization, which is the chemical turning into a gas and moving through the air, and degradation, which is the chemical breaking down chemically or biologically in place.