Which soil horizon is commonly referred to as topsoil?

The soil horizon commonly referred to as topsoil is the A horizon. This layer is crucial for plant growth and agricultural productivity. Topsoil is composed of a mixture of organic matter, minerals, and nutrients, making it rich in the essential components that plants require for healthy development.

The A horizon is located right beneath the O horizon, which consists primarily of organic material such as decomposed leaves and other plant material, but the A horizon includes both organic and mineral content. It is the layer where most biological activity occurs, and it serves as the primary zone for root development and nutrient uptake for most plants.

This layer typically has a darker color compared to other horizons due to the higher concentration of organic matter, which also enhances moisture retention and microbial activity. The presence of organisms in the A horizon plays a crucial role in breaking down organic materials, further enriching the soil and making it more conducive for supporting plant life.

Understanding the distinct characteristics of different soil horizons helps in effective soil management and agricultural practices, pointing to the importance of the A horizon as a vital resource in agronomy.