What soil horizon is characterized by having the highest amount of organic matter?

The A horizon, also known as the topsoil, is characterized by having the highest amount of organic matter, which is crucial for plant growth and soil fertility. This layer is typically darker in color compared to the layers below it due to the accumulation of organic material from decomposed plants and microorganisms. The presence of this organic matter enhances the soil’s structure, nutrient capacity, and water retention, making it vital for sustaining plant life.

In comparison, the E horizon, which may be present in some soil profiles, is primarily a leached layer where minerals and organic matter have been washed out, leading to a lower concentration of organic material. The C horizon consists of weathered parent material and contains little to no organic matter, mainly consisting of larger rock fragments or unconsolidated material. The B horizon, often referred to as subsoil, can have some accumulation of materials leached from above but typically does not have the same high concentration of organic matter as the A horizon.

This understanding of soil horizons highlights the crucial role of the A horizon in ecosystems, particularly regarding its contribution to soil health and plant productivity.