How many acres are we speaking of, you might need 7 tons over the long haul , dont even try to put it on at one time, put some on now , later this year, and it will probaly take about a year and a half or more to apply 7 tons of lime per acre, I doubt it needs that much, once you start it will bring the ph up and maybe even improve the readings to the point of not needing all that much . 4.6 does not sound like 7 tons to me....