What term is used to describe the layer of soil that contains organic material?

The term that describes the layer of soil containing organic material is the A horizon. This layer, often referred to as the topsoil, is rich in nutrients and is critical for plant growth as it consists of a mixture of mineral particles, organic matter, water, and air. The organic material in the A horizon primarily comes from decomposed plants and animals, which enriches the soil and contributes to its fertility.

The A horizon is usually the topmost layer of the soil profile and plays a crucial role in the ecosystem by supporting a diverse range of organisms, including microorganisms that facilitate nutrient cycling. This layer is vital for agriculture and gardening, as it is where most root systems are found and from where plants absorb the majority of their nutrients and water. Understanding the characteristics and importance of the A horizon can help in effective soil management and agricultural practices.