The bottom layer of soil is called bedrock.

Explanation:
- Soil is made up of different layers, also known as horizons. Each layer has distinct characteristics and plays a crucial role in supporting plant growth.
- The bottommost layer of soil is called bedrock. It is the solid rock layer that lies beneath the soil horizons.
- Bedrock is made up of various types of rocks, such as granite, limestone, or sandstone, depending on the geological composition of the region.
- Unlike the other soil layers, bedrock does not contain organic matter, minerals, or nutrients that are essential for plant growth.
- Bedrock serves as a foundation for the layers of soil above it and provides stability to the soil profile.
- It acts as a barrier, preventing the deeper layers of the earth from mixing with the upper layers of soil.
- Bedrock also affects the drainage capacity of the soil. If the bedrock is impermeable, it can hinder the movement of water through the soil.
- The depth of the bedrock can vary greatly from one location to another. In some areas, it may be close to the surface, while in others, it may lie several meters or even kilometers deep.
- The presence of bedrock can influence the composition and characteristics of the soil layers above it.
- In areas where bedrock is close to the surface, the soil may be shallow, limiting the depth of plant roots and affecting their ability to access water and nutrients.
- Understanding the properties of the bedrock is essential for activities such as construction, agriculture, and geology, as it can impact the stability of structures, the fertility of the soil, and the formation of landscapes.