Na2CO3 -----à 2Na + + CO3=
2Na+ + CO3= + 2HOH -----à 2Na+ + 2OH - + H2CO3
since sodium hydroxide dissociates to a greater degree than the carbonic acid, OH ions dominate and give rise to alkalinity. This may be as high as 9 or 10. These soils most commonly occur in arid and semi-arid regions.