No, just because you have clay soil does not mean your soil is acidic. We have tested hundreds of lawns throughout the area and it is a 50/50 shot of the soil being acidic. If your soil is indeed alkaline and you add limestone unknowingly you will cause the conditions to get worse. Also, if you know for sure your soil is acidic you still don’t know how many pounds per thousand sq-ft of limestone to apply. It is best to have a soil analysis done before attempting any corrective actions.