Like Foreman said, granules usually need to be covered, that's why I liked the blocks. I think you will get a better idea how much they need with the blocks and they are fairly cheap ($10 or so).
One more point if you want one:laughing: Make yourself a drag for the manure, mine was 6" I-beam with 2 joints of 2-3/8" pipe welded to chains, but I was dragging up to over 100 acres at a time, you could get it done with a cattle panel (4 guage wire) with some added wight. Use the drag to flatted and spread the manure in your pasture, cows wont eat near a pile of poo. Why you see in some pastures nice Green grass around poo piles, needs to be spread out.