Which statement best describes a highly soluble pesticide's behavior in soil?

• A. Highly soluble pesticides are strongly adsorbed and stay put
• B. Highly soluble pesticides evaporate quickly
• C. Highly soluble pesticides degrade immediately
• D. Highly soluble pesticides are poorly adsorbed and more likely to leach

Answer: (D)

When a pesticide is highly soluble, it tends to stay dissolved in soil water rather than sticking to soil particles. Mobility in soil comes from how much the chemical adsorbs to soil surfaces versus how much remains in the water. If it isn’t strongly adsorbed, it moves with the water that infiltrates soil after rain or irrigation. That downward movement, carried by percolating water, means it’s more likely to leach toward deeper soil layers and potentially into groundwater.

Evaporation depends on volatility, which isn’t dictated by solubility alone, and immediate degradation isn’t guaranteed either—the key idea here is the relationship between solubility, adsorption, and leaching. So the best description is that highly soluble pesticides are poorly adsorbed and more likely to leach.