I don't think there's any fixing it. The problem is the source of nitrogen... Fertilizer that's more neutral has more nitrate nitrogen and fertilizer that's more acidic has more ammonium/urea nitrogen. Your fertilizer is all ammonium/urea nitrogen with an added 15% sulfur to make it even more acidic. The absolute only thing you can use your Jack's 21-7-7 on are acid loving plants. Adding other materials will not change the acidic properties of the nitrogen.
