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Solonetz
Definition
Soils having a natric horizon within 100 cm of the
surface, causing the lower part of the topsoil has a higher
amount of clays. Solonetz is then dense and has a high
proportion of exchangeable sodium and, in some cases,
also exchangeable magnesium. They can also contain free
soda (Na CO ) that results in strongly alkaline (pH>8.5).
2 3
Distribution
Solonetz occur worldwide about 843 million rais
where there is a predominance of sodium over calcium
salts in soils.
In Thailand, these soils cover countrywide 1.23
million rais, mostly in the northeast region of Korat basin
such as Nakhon Ratchasima, Mahasarakham, and Roi Et
provinces, followed by in the west regions, respectively.
Formation
Solonetz are generally developed in flatlands in a climate with hot and dry or with
(former) coastal deposits that contain a high proportion of sodium ions. They can also be derived
from the parent material of sodium carbonate or bicarbonate salts, for instance, in the northeast
region of Thailand where the formation of sodium carbonate is predominant and can raise the
pH to over 8.5.
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