North Carolina Pesticide Application Practice Test

How does high organic matter affect leaching?

1. It increases leaching

2. It makes leaching more difficult

3. It has no effect on leaching

4. It only affects surface runoff

The correct answer is: It makes leaching more difficult

High organic matter in soil significantly enhances its structure and water retention properties. Organic matter promotes the formation of aggregates, which improves soil porosity and water infiltration. When there is an increase in organic matter, the soil can hold more moisture and nutrients, leading to reduced movement of these elements downward through the soil profile, a process known as leaching. While leaching refers to the downward movement of soluble substances (like nutrients and pesticides) from the upper soil layers to deeper layers, high organic matter can create conditions that inhibit this movement. It binds nutrients and enhances the soil's capacity to retain them, thereby making it more difficult for these substances to be leached away. This is crucial for maintaining nutrient levels in the planting zone and preventing the loss of essential elements from the soil. In contrast, other options reflect misunderstandings about the role of organic matter. For instance, stating that it increases leaching overlooks the soil's enhanced ability to retain nutrients and moisture. Similarly, claiming it has no effect ignores the significant influence organic matter has on soil dynamics and nutrient management. Mentioning only surface runoff neglects the broader implications of organic matter on soil health and nutrient retention, as runoff refers specifically to water moving over the surface rather than the vertical movement occurring during