What about crushed limestone?

Recently I visited a limestone plant called Graymont in Canada which produces a product that does exactly that: improves sodic soils. Maybe its webpage will have the information you need.

Dear Michael, can you send the link and chemical formula and process of its use. Thanks for your answer dear,

Coal-fired power plants that have sulfur scrubbers often produce a gypsum by-product. But perhaps there are heavy metal contamination issues?

Another by-product option is ground clam shell. Perhaps  a shellfish industry near the coast could provide materials? It might not be enough, but could be a supplemental source.

I have also seen high-Ca granite used in a rock dust form.

Otherwise, I know synthetics like Sul-Po-Mag mixtures are used successfully.

But I favor cheap, renewable, sustainable sources.

Good Luck!

Thanks Dear Erik B. Melchiorre, Yes of course we have to look for cheaper material which can be applied directly. Pyrite also one of the option but we have to careful for heavy metal contamination too. Thanks

look under www.graymont.com

section on lime, agriculture

Thanks Dr Michael Issigonis for the link. Regards 

Crushed limestone (carbonates) are useful for many soil amendment purposes, but scarcely in this case.  Gypsum is particular in that sense that sulphate is mobile and Carries With it sodium ions, leaving Calcium behind to bridge the soil colloids.

However, one Fertilizer having come up recent 50 years, is micronised Silicon (amorphous SiO2), which strengthens the plants to grow on alkaline soils, and also againts drought stress.  It is available as a secondary Product from the Silicon industry, in most cases a very pure material.  There are many producers all around world, also in Asia. Just to mention, myself I have participated in Projects together With the Chinese Bluestar Company, which also has a large industry in Our country Norway, and worldwide, www.Elkem.no.  That is just an option among others.

Thanks Dr Karl-Jan Erstadfo such a nice information. Can you give some more detail on this by product called micronised Silicon.

Thanks

Dear Dr. Sarwan Kumar Dubey,

You will find a lot of Research results following this link on the subject.

https://scholar.google.no/scholar?hl=no&q=Silicon+in+agriculture&btnG=

Concerning Commercial Products, you could be very well informed contacting one of my colleagues in the industry, With this e-mail address:  Magne Dastol .  He has a lot of experience from Asia, working many years in China.

Best regards,

,Dr. Karl-Jan Erstad

Thanks @ Karl-Jan Erstad for this wonderful link and email ID of Mr Dastol.