Illinois Pesticide Applicator Practice Test

What factors influence a pesticide's leaching ability?

1. Soil acidity and temperature

2. Soil texture and organic matter

3. Pesticide formulation and application method

4. Weather conditions during application

The correct answer is: Soil texture and organic matter

Soil texture and organic matter are significant factors that influence a pesticide's leaching ability. Soil texture refers to the size of soil particles, which affects how water moves through the soil and thus how easily pesticides can leach down past the root zone into groundwater. Soils with larger particles, like sandy soils, typically allow for quicker drainage and can lead to increased leaching. In contrast, finer-textured soils, like clay, tend to retain water and can slow the movement of pesticides through the profile. Organic matter plays a critical role as well, since it can bind to pesticides, reducing their mobility. Soils rich in organic matter may retain pesticides more effectively, thereby decreasing the likelihood of leaching into groundwater. The more organic material present in the soil, the more it can adsorb the chemicals, which ultimately influences the amount that can leach away from the site of application. While other factors, like soil acidity and temperature, pesticide formulation and application method, and weather conditions during application, can affect pesticide performance and behavior, soil texture and organic matter are primary determinants of how easily a pesticide can leach through the soil profile to potentially contaminate groundwater resources.