Texas FFA Nursery Landscape Practice Exam

Tree roots that are responsible for most nutrient uptake are found:

1. Outside the dripline

2. Within the upper 8" of topsoil

3. In the subsoil

4. Between 18" and 28" in depth

The correct answer is: In the subsoil

Tree roots that are responsible for most nutrient uptake are typically found within the upper 8 inches of topsoil. This layer is where organic matter and nutrients tend to be concentrated due to decomposition and interaction with the soil environment. In this region, roots can efficiently absorb water and essential minerals needed for the tree’s growth. The subsoil, while it may contain some nutrients, is usually denser and less aerated than the topsoil, which can impede root growth and nutrient absorption. Additionally, subsoil may not have the same richness in organic material that upper topsoil does. Therefore, while some roots may penetrate deeper layers for stability or water access, the majority of nutrient uptake occurs in the upper layer of the soil profile.