Genesis

The formation of the argic horizon takes place by a clay eluviation/illuviation process, which can be explained as follow: :

dry soil at the end of the end of dry season ...
... when the first rains arrive, precipitation waters moving through the surface horizon ...
... brings clay into suspension ...
Suspensions quickly cross the E horizon as it is very sandy.
... by gravity this suspension infiltrates along macropores to deeper, dryer horizons ...
... Because of a higher suction there by the micropores, compared to the macropores, water will be absorbed ...
... As a result a thin film of suspension will coat the walls of the macropores. As the clay particles cannot enter the micropores, they concentrate in this film ...
... Finally, when all the water has been sucked from the macropores, the clay particles remain sticking to the walls, showing a strong adhesion between each other and with respect to the wall of the void, and show a parallel arrangement ...

... During the next wet period this process is repeated, resulting in an increasingly thicker clay coating. These coatings are called clay coatings by their nature and illuviation coatings by their genesis.

In the same way water enters the micropores of peds, leaving on their surface an illuvial clay coating.

Index | Next

Top