Dear Kamal,

There are lot of benefits for Gypsum on sodic soils etc, you can further find more information from following links and I think you can find more information and would be fruitful for you

http://landresources.montana.edu/nm/documents/NM8.pdf

http://www.fao.org/docrep/x5871e/x5871e05.htm

http://www.fao.org/docrep/x5871e/x5871e04.htm

http://landresources.montana.edu/nm/documents/NM8.pdf

Thanks!

Gypsum is neutral in pH. It has no carbonate ion as part of its make up , therefore, it will not neutralize soil acidity.

No. For acidic soils lime is used.For soils with a pH around 7,Ca ions are of considerable amount both on exchange sites and as soluble cations.