Podsolisation is an extreme form ofleaching which causes theeluviation ofiron andaluminiumsesquioxides.[1]
The process generally occurs in areas whereprecipitation is greater thanevapotranspiration. The minerals are removed by a process known asleaching.
When organic material is broken down nutrients are released, but at the same time organic acids are released. These organic acids are known aschelating agents. Manypodsol soils form underneathconiferous forests, the fact that pine trees are evergreen causes a very thinlitter layer inhibiting the production ofhumus. As a result, an acidic (pH 4.5)mor humus is produced which provides a greater amount of chelating agents.[2]
In podsolisation, chelating agents break down clay and release minerals such as iron and aluminium. When iron and aluminium are hydrated they become sesquioxides. The sesquioxides are translocated from the A Horizon, a zone of out-washing, to the B Horizon, a zone of illuviation. Many bases such ascalcium andpotassium are alsoleached from the zone along with organic matter andsilica. Often minerals likequartz and silica are left behind in the A horizon. What is significantly different about podsols in comparison to other soils is that the bottom of A horizon is known as the AE horizon, which is an eluviated area which has lost sesquioxides. It tends to be an ash gray colour.[3]
The B Horizon has dark layer where minerals, organic matter and bases are being illuviated (washed in/accumulated). Below this is a red/orange layer of iron and aluminium sesquioxides deposit. Some bases remain in the soil, though others may be lost bythroughflow. In many podsols,Iron Pans are created. This can cause water logging which may then saturate the A horizon leading tomottling or agleyed podsol.
Also useful:soil chemistry
 | Thissoil science–related article is astub. You can help Wikipedia byexpanding it. |
 | Thisgeochemistry article is astub. You can help Wikipedia byexpanding it. |