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Horizon A typically consists of a mix of organic matter and minerals like clay, silt, and sand, making it fertile for plant growth. This layer is often referred to as topsoil and is important for supporting plant roots and providing essential nutrients.
The horizons of a soil profile are O horizon (organic matter), A horizon (topsoil with organic material), E horizon (zone of leaching), B horizon (subsoil with accumulation of minerals), C horizon (weathered parent material), and R horizon (bedrock).
Materials leached from horizon A are typically deposited in the B horizon of the soil profile. As water moves through the soil, it carries minerals and nutrients from horizon A and deposits them in the B horizon.
The correct order of soil horizons, from top to bottom, is O horizon, A horizon, E horizon, B horizon, C horizon, and R horizon. It is important to note that not all soils have all these horizons, as they can vary depending on the specific conditions of the soil.
The soil horizon that has the darkest and richest soil is usually the topsoil layer, known as the A horizon. This layer contains a high amount of organic matter and nutrients, making it ideal for plant growth.
The three distinct soil horizons in a mature soil profile are: the topsoil (A horizon), the subsoil (B horizon), and the parent material (C horizon). Each horizon has unique characteristics and composition that contribute to the overall soil profile.