Certified Crop Advisor Practice Exam

What is a disadvantage of using a clean till system?

1. Disease and weed spread

2. Improved soil health

3. Enhanced moisture retention

4. Increased organic matter

The correct answer is: Disease and weed spread

Using a clean till system often leads to increased susceptibility to disease and weed spread. This occurs because tillage disrupts the soil structure and exposes seeds and pathogens that reside in the soil. When the soil is turned over, it can bring dormant weed seeds to the surface, where they receive light and moisture, allowing them to germinate more readily. Additionally, the mechanical disturbance can weaken the natural defenses of soil ecosystems, promoting the proliferation of certain soil-borne diseases by disrupting beneficial microorganisms that compete with pathogens. In contrast, options that mention improved soil health, enhanced moisture retention, and increased organic matter are often associated with conservation tillage practices, which aim to maintain soil structure and health. Clean tillage typically reduces the levels of organic matter as it continuously disturbs the soil, leading to degradation rather than improvement in soil health.