What does the top layer of the soil profile consist of?

The top layer of the soil profile primarily consists of an organic layer mixed with minerals. This layer, known as the topsoil, is crucial for plant growth as it contains a rich blend of organic matter, nutrients, and microorganisms that contribute to soil fertility. The organic matter, which includes decomposed leaves, plant material, and other organic debris, provides essential nutrients for plants and improves soil structure, aeration, and water retention. This combination of organic matter and mineral particles makes topsoil vital for sustaining ecosystems and agricultural productivity.

While other layers of the soil profile do contain minerals, they do not feature the significant organic content that characterizes the top layer, which is specifically designed to support life and growth. In contrast, clay and silt primarily refer to soil texture types, weathered bedrock pertains to deeper layers of the soil profile, and unweathered minerals are typically found in the bedrock layer beneath the soil surface.