We have 1/2 acre of food plots on our land and we usually use about 9-10 gallons. I also mix it about 3-4 times stronger than the recommended mix. For my plots, it usually takes about 3 weeks for everything to be dead, after 1 week the grass will start turning a little yellow, 2 weeks the grass will be dead, but for the thicker weeds and underbrush it may take a full 3 weeks to kill it all. Once everything is dead its pretty easy to clear. As far as putting lime down, it should be put down 6 months before planting, it won't do any good if you put it down right before planting.