That is Spatterdock. A gallon will make about 75 gallons the way I mix it and would last you a long time. The really easy way to apply it is to get a 15 gallon electric sprayer for about $60 at the farm box stores and fasten it to your yard mower or pull it in a yard trailer.
I'm one of the few that likes Spatterdock as I use it as a backdrop in my photography.
