Ornamental and Turf Pesticide Applicators Practice Exam

What happens to pesticides in the soil over time?

1. They remain unchanged indefinitely

2. They are absorbed by plant roots

3. They are eventually broken down by bacteria and fungi

4. They evaporate into the atmosphere

The correct answer is: They are eventually broken down by bacteria and fungi

Pesticides in the soil are subject to various biological processes, and one of the primary ways they are managed is through degradation by microorganisms such as bacteria and fungi. These microorganisms play a crucial role in the soil ecosystem, breaking down chemical compounds into simpler, less toxic substances over time. This process, known as biodegradation, can vary significantly based on factors such as the type of pesticide, soil temperature, moisture levels, and the presence of specific microbial populations. While there are pesticides that may persist in the soil for extended periods, especially if they are designed to be stable, most will not remain unchanged indefinitely. Environmental factors and microbial activity actively contribute to their breakdown. The absorption of pesticides by plant roots can occur but does not represent the primary fate of pesticides in soil over time; rather, it's more about the movement and uptake during specific conditions rather than a long-term process. Evaporation is a concern for certain volatile pesticides, but it typically affects pesticides applied to the surface rather than those that become incorporated into the soil matrix, which biases the long-term considerations. Hence, the active microbial degradation is the most significant process that determines what happens to pesticides in the soil as time progresses, making this understanding essential for effective pest management and environmental protection.