MDARD Michigan Core Pesticide Applicator Practice Exam

In terms of leaching, which pesticide characteristic would result in greater leaching?

1. Low solubility

2. High adsorption

3. High persistence

4. High solubility

The correct answer is: High solubility

The concept of leaching refers to the process by which soluble substances are washed out from the soil or surface environment, typically carried away by water movement. When considering pesticide characteristics, high solubility plays a crucial role in increasing the likelihood of leaching. A pesticide that is highly soluble in water can easily dissolve and, when it rains or when irrigation occurs, the dissolved pesticide can more readily move through the soil profile. This movement can lead to the pesticide moving beyond the root zone of plants into groundwater or surface water bodies, contributing to environmental contamination. In contrast, characteristics such as low solubility or high adsorption would inherently limit the movement of pesticides through the soil, as these would either not dissolve well in water or would bind tightly to soil particles, making it less likely for them to leach away. High persistence refers to how long a pesticide remains effective in the environment, which doesn't directly influence its likelihood of leaching. Overall, a pesticide's high solubility is the key factor that facilitates leaching, making it more prone to being washed away from the application site and into less desirable areas.