When I said "What" you are spraying, I meant the chemicals. Most are applied on a per acre basis and most need enough water to get an even application. A few things, like crop oil, are applied by a %v/v. Calibrating a sprayer is more problematic with an ATV or UTV because it is harder to hold a constant speed as terrain changes than it is with a tractor. Once you set pressure and make trial runs, you'll know how much fluid you are putting out per acre. My boomless sprayer puts out a lot of water quickly and you need to move pretty fast and it is pretty inaccurate. The droplets are large and thrown a long distance. It is smaller and I don't get much acreage covered with it. The boom sprayer on my tractor puts out fine droplets close to the ground for little drift and it is much more accurate. I've calibrated it for different tractor gears so if terrain is rough, I can run it on a lower gear. It puts out more water so it covers less acreage per tank and I adjust the amount of chemical accordingly. If terrain is not rough, I run in a faster gear so I get more acreage per tank and adjust the amount of chemical accordingly for that.
Thanks,
jack