Which soil characteristics help to hold pesticides and reduce movement to groundwater?

Which soil characteristics help to hold pesticides and reduce movement to groundwater?

• A. Coarse texture
• B. High clay content and high organic matter
• C. Very low organic matter
• D. Sandy soils

Answer: (B)

Soils that hold pesticides and keep them from reaching groundwater rely on adsorption to soil particles. Clay minerals and organic matter provide a lot of surface area and charged sites where pesticide molecules can cling. When pesticides are adsorbed to these surfaces, they’re less likely to travel with infiltrating water, reducing downward movement. High clay content offers numerous adsorption sites due to the minerals’ charged surfaces, and high organic matter adds even more sites and a favorable environment for chemical binding. This combination also helps retain water in the upper soil, slowing percolation. Sandy soils, with their large pore spaces and low surface area, provide fewer places for pesticides to bind, so water and dissolved pesticides can move more readily downward. Very low organic matter means fewer binding sites as well, increasing the chance of leaching. Thus, the soil with abundant clay and organic matter best minimizes movement to groundwater.

Soils that hold pesticides and keep them from reaching groundwater rely on adsorption to soil particles. Clay minerals and organic matter provide a lot of surface area and charged sites where pesticide molecules can cling. When pesticides are adsorbed to these surfaces, they’re less likely to travel with infiltrating water, reducing downward movement.

High clay content offers numerous adsorption sites due to the minerals’ charged surfaces, and high organic matter adds even more sites and a favorable environment for chemical binding. This combination also helps retain water in the upper soil, slowing percolation.

Sandy soils, with their large pore spaces and low surface area, provide fewer places for pesticides to bind, so water and dissolved pesticides can move more readily downward. Very low organic matter means fewer binding sites as well, increasing the chance of leaching. Thus, the soil with abundant clay and organic matter best minimizes movement to groundwater.