I am currently putting 300 lbs of urea into a 400 gal tank. I think there is a myth about slow release nitrogen once it is the solution. I use a feed grade 46-0-0 and uflex, had the uflex left over is the only reason that I am currently using it. Mix at a rate of 200 urea and 100 uflex per batch. Spray at 1.5gpm or a rate of 62 gal/acre. Will see some nitrogen burn in hot weather so adjust rate according to the temp.