The usual methods are to suspend the soil in water ( 5 g/10 ml) and shake for 1 h, measure the EC then the pH. Then add CaCl2 solution to make the solution 10 mM in CaCl2, or KCl solution to make the solution 1 M, and a final vol of 25 mL, Shake again for 1 h then remeasure the pH.

Dear Rajaram Choudhary . See the following useful link: https://www.awri.com.au/wp-content/uploads/v_activity_soil_ph.pdf

Kindly see also the following useful link: https://extension.oregonstate.edu/measuring-soil-ph

Also check please the following good link: http://vro.agriculture.vic.gov.au/dpi/vro/vrosite.nsf/pages/soilhealth_measure_ph