Which layer of soil generally corresponds to significant nutrient absorption?

The A horizon, often referred to as the topsoil, is the layer where significant nutrient absorption occurs. This layer is rich in organic matter and is vital for plant growth. It contains a mixture of mineral particles, decomposed organic material (humus), and living organisms, all of which contribute to its fertility. The high organic content enhances the soil's ability to retain moisture and nutrients, making it an essential layer for vegetation.

In terms of soil layers, the O horizon consists mainly of organic material, such as decomposed leaves and many microbes, but it doesn't provide the nutrients in a form accessible to plants to the same extent as the A horizon. The B horizon, while also important, typically serves as a zone of accumulation for minerals leached from the layers above and may lack the organic matter crucial for nutrient availability. The C horizon is composed of weathered parent rock and does not actively contribute to nutrient absorption for plants, as it usually contains very little organic matter. Thus, the A horizon is the layer primarily responsible for notable nutrient absorption.