Which statement is true about leaching?

Which statement is true about leaching?

• A. Leaching is more likely when water movement downward is plenty.
• B. Leaching is more likely when there is lots of downward water movement.
• C. Leaching is unrelated to soil type.
• D. Leaching occurs only in dry soils.

Answer: (B)

Leaching is the downward movement of dissolved pesticide with infiltrating water through the soil. When water moves downward a lot—after heavy rain or extensive irrigation—the dissolved chemical can be carried deeper into the soil profile, past the root zone and toward groundwater. This tendency is influenced by soil properties: sandy soils with large pores offer less surface area to hold pesticides, so water and the chemical tend to move more quickly; soils rich in clay or organic matter tend to adsorb more chemical and slow or reduce downward movement. The pesticide’s own characteristics matter too—high water solubility and low soil adsorption increase the chance of leaching. So leaching is most likely under conditions of substantial downward water movement, not in dry soils and not unaffected by soil type.

Leaching is the downward movement of dissolved pesticide with infiltrating water through the soil. When water moves downward a lot—after heavy rain or extensive irrigation—the dissolved chemical can be carried deeper into the soil profile, past the root zone and toward groundwater. This tendency is influenced by soil properties: sandy soils with large pores offer less surface area to hold pesticides, so water and the chemical tend to move more quickly; soils rich in clay or organic matter tend to adsorb more chemical and slow or reduce downward movement. The pesticide’s own characteristics matter too—high water solubility and low soil adsorption increase the chance of leaching. So leaching is most likely under conditions of substantial downward water movement, not in dry soils and not unaffected by soil type.