B Horizon

A mineral soil layer which is below an 'A' Horizon. It is commonly referred to as subsoil. It will typically be lighter in colour and less fertile than the 'A' Horizon. It may also be poorly drained due to finer, especially clay, particles having washed down from the higher layer. It is also called the zone of illuviation to indicate that material has accumulated in this layer. Some examples of elements that can collect in this layer are iron (potentially forming an iron pan) or calcium carbonate layer.