Which horizon is known as the zone of leaching with downward movement of water?

The A Horizon, often referred to as the topsoil, is characterized as the zone where leaching occurs due to the downward movement of water. This layer typically contains a high concentration of organic matter and nutrients, making it crucial for plant growth. As rainwater or irrigation water infiltrates this horizon, it percolates downward, dissolving minerals and nutrients as it moves through the soil layers. This process of leaching is significant as it influences soil fertility and structure.

In contrast, other horizons like the B Horizon, which is often called the subsoil, typically accumulate materials leached from the upper layers but do not experience the same initial leaching processes. The C Horizon consists of weathered rock and is less affected by biological activity, while the O Horizon is made up of organic matter and organic-rich material on the surface, primarily comprising decomposed leaves and plant materials. Thus, the A Horizon is distinctly known for its role in the leaching process.