What does a restrictive layer in soil do?

A restrictive layer in soil primarily functions to impede water movement and root growth. This layer can be composed of compacted soil, clay, or other materials that limit the infiltration of water and restrict the spread of roots, making it difficult for plant life to establish and thrive. When water cannot move through this layer effectively, it can lead to poor drainage, waterlogging above the layer, and even lead to insufficient water accessibility for plants, all of which negatively affect plant health and soil ecology.

While the other options may describe beneficial soil characteristics, they do not accurately reflect the impact of a restrictive layer. Enhancing water absorption and promoting healthy plant growth are traits associated with well-aerated and structured soil, which allows for proper root development and water infiltration. As for acting as a filtration system for waste, this is not typically a function of restrictive soil layers; instead, filtration is usually facilitated by well-drained, permeable materials that allow for the movement and processing of water and contaminants through the soil profile.