We dont get this compliacted hard to predict pH more important how much lime to get alkalinity to over 20ppm. I recommend 6 tons/acre so 28 tons round down to closest truck load of 24-25 tons. It sounds like alot but this should get back into the range you need and hopefully future plan every two years add 8-10 tons or whenever alkalinity drops below 20. Your high rentention time helps greatly.
