What is the main role of soil horizon 'E'?

The main role of soil horizon 'E' is indeed associated with the leaching of nutrients. This layer, found beneath the surface horizon (often 'O' or 'A'), commonly experiences significant leaching processes due to the movement of water through the soil profile. As water percolates through the 'E' horizon, it can carry away essential nutrients, minerals, and organic matter, leading to a lighter-colored layer that is depleted of these substances. This horizon is often referred to as the "eluviation" horizon, where the term 'eluviation' refers specifically to the leaching process that characterizes it.

The correct answer highlights the significance of leaching in shaping soil composition. In contrast, other choices like organic layer formation pertain to different horizons, usually the 'O' or 'A' horizons, which are rich in organic material. The option regarding aeration of soil relates to the physical properties of the soil, which are influenced by its texture and structure rather than specifically attributed to the 'E' horizon. Lastly, rock mineralization is a process that occurs in deeper soil horizons and parent material, not primarily in 'E'. Overall, understanding the role of the 'E' horizon enhances the knowledge of soil formation and nutrient dynamics