MDARD Michigan Core Pesticide Applicator Practice Exam

Which soil characteristic is likely to increase the leaching of contaminants into groundwater?

1. Soil texture

2. Soil structure

3. Organic matter content

4. Soil depth

The correct answer is: Soil texture

Soil texture is a critical factor influencing the leaching of contaminants into groundwater. Sandy soils, for example, have larger pore spaces and can facilitate quicker water movement compared to clay soils, which are denser and retain water more effectively. As water moves rapidly through sandy soils, any soluble contaminants present are also transported down through the soil profile, increasing the likelihood of leaching into groundwater. In contrast, soil structure, organic matter content, and soil depth can have varying effects on leaching. Good soil structure can enhance water retention and reduce leaching, while high organic matter content generally helps to bind contaminants, reducing their mobility. The depth of the soil may affect how far contaminants can travel before reaching groundwater but doesn't directly influence the rate of leaching as soil texture does. Understanding these interactions helps in managing soil and preventing groundwater contamination.