You're probably going to spray it with a 2 gallon pump sprayer or maybe a 4 gallon pump sprayer. Mix your Roundup at 2%. (that's assuming you're using a 41% glyphosate concentrate). That's roughly 2.5 ounces per gallon, or 5 ounces in your 2 gallon sprayer, or 10 gallons in your backpack sprayer. While you are at it, mix some nitrogen in with the herbicide. It'll make the gly work better, and it'll help your food plot when you plant it. Ammonium nitrate, ammonium sulphate, or even straight ammonia. I used to mix epsom salts with household ammonia and some dishwashing detergent when making a batch of gly.