Good question of practical nature and explained well by Guido, Raj and Sharma by giving references. Gypsiferous soils are also found in Qatar. I think, the problem has been explained well.

Icarda handbook on soils has got a specific section. Ca Sulèhate is soluble in water and acetone precipitates it. After purification you may apply conducimetry, atomic absorption or sulphate wet chemistry. The manual is on line under Icarda+soil analysis+Ryan

Generally gypsum contents are determined  through analyzing the sample for S and Ca contents for which so many methods in different books and manuals are given, even in USDA Hand Book 60. Dear Pravash Chandra Moharana have look of these books and select method you can follow base on the resources available in your laboratory.

Good question of practical nature and explained well by Guido, Raj and Sharma by giving references. Gypsiferous soils are also found in Qatar. I think, the problem has been explained well.

Your question brought  my mind Xray Diffraction Technique (XRD) which is used to determine compounds of soil. 

Apart from Abhishek's cited references, methods described in ML Jackson book on Soil Chemical Analysis  may be referred.

By soluble soil with water and making Shaker and take 20 ml from solution and add 20 ml from acetone, after that put in centerfuge and calculate electrical conductivity…  reference icarda 2016