Podsolisation
Encyclopedia
Podsolisation is an extreme form of leaching
which causes the eluviation
of iron
and aluminium
sesquioxide
s.
The process generally occurs in areas where precipitation
is greater than evapotranspiration
. The minerals are removed by a process known as leaching
.
When organic material is broken down nutrients are released, but at the same time organic acids are released. These organic acids are known as chelating agents. Many podsol
soils form underneath coniferous forests, the fact that pine trees are evergreen causes a very thin litter layer inhibiting the production of humus. As a result an acidic (pH 4.5) mor humus is produced which provides a greater amount of chelating agents.
and Potassium
are also leached from the zone along with organic matter and silica. Often minerals like quartz
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 alleviated area which has lost sesquioxides. It tends to be an ash gray colour.
. In many podsols, Iron Pans are created. This can cause water logging which may then saturate the A horizon leading to mottling or a gleyed podsol.
Also useful: soil chemistry
Leaching (pedology)
In pedology, leaching is the loss of mineral and organic solutes due to percolation. It is a mechanism of soil formation. It is distinct from the soil forming process of eluviation, which is the loss of mineral and organic colloids. Leached and elluviated materials tend to be lost from topsoil and...
which causes the eluviation
Eluvium
Eluvium is the moniker of ambient recording artist Matthew Cooper, who currently resides in Portland, Oregon. Cooper, who was born in Tennessee and raised in Louisville, Kentucky before relocating to the Northwest, is known for blending various genres of experimental music including shoegaze,...
of iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
and aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
sesquioxide
Sesquioxide
A sesquioxide is an oxide containing three atoms of oxygen with two atoms of another element. For example, aluminium oxide is a sesquioxide.Many sesquioxides contain the metal in the +3 oxidation state and the oxide ion, e.g., Al2O3, La2O3...
s.
The process generally occurs in areas where precipitation
Precipitation (meteorology)
In meteorology, precipitation In meteorology, precipitation In meteorology, precipitation (also known as one of the classes of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation...
is greater than evapotranspiration
Evapotranspiration
Evapotranspiration is a term used to describe the sum of evaporation and plant transpiration from the Earth's land surface to atmosphere. Evaporation accounts for the movement of water to the air from sources such as the soil, canopy interception, and waterbodies...
. The minerals are removed by a process known as leaching
Leaching (pedology)
In pedology, leaching is the loss of mineral and organic solutes due to percolation. It is a mechanism of soil formation. It is distinct from the soil forming process of eluviation, which is the loss of mineral and organic colloids. Leached and elluviated materials tend to be lost from topsoil and...
.
When organic material is broken down nutrients are released, but at the same time organic acids are released. These organic acids are known as chelating agents. Many podsol
Podsol
In soil science, podzols are the typical soils of coniferous, or boreal forests. They are also the typical soils of eucalypt forests and heathlands in southern Australia...
soils form underneath coniferous forests, the fact that pine trees are evergreen causes a very thin litter layer inhibiting the production of humus. As a result an acidic (pH 4.5) mor humus is produced which provides a greater amount of chelating agents.
The A Horizon
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 as CalciumCalcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
and Potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
are also leached from the zone along with organic matter and silica. Often minerals like quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
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 alleviated area which has lost sesquioxides. It tends to be an ash gray colour.
The B Horizon
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 by throughflowThroughflow
In hydrology, throughflow is the horizontal movement of water in the soil zone. This type of flow must first emerge on land before it enters a body of surface water to be considered throughflow...
. In many podsols, Iron Pans are created. This can cause water logging which may then saturate the A horizon leading to mottling or a gleyed podsol.
Also useful: soil chemistry
Soil chemistry
Soil chemistry is the study of the chemical characteristics of soil. Soil chemistry is affected by mineral composition, organic matter and environmental factors.-History:...