This is all very interesting, but not really the most relevant discussion regarding how to properly spay 10 acres. You could theoretically spray at any speed as long as you get enough chemical on the ground. (Think crop duster.)
With any spray, the goal is to apply x gallons per acre. Best approach, in my opinion, is to put 10 gallons or 30 gallons in your sprayer and then drive the speed that feels right on your tractor, and on your land, and see how far it goes. You can just do this with water if you want -- I'd do it with my first tank of spray and then adjust from there.
I have a really handy 40 gallon sprayer, 3 pt. hitch, that I use on a 30 HP Kubota. I know that driving a decent comfortable reasonable speed over my fairly rough terrain that it will put down right at 30 gallons per acre using the boom sprayer. Once you establish that, the rest is easy.
Forget speed. Mark off an acre. For example, if you find that it takes you 30 gallons to cover an acre at the speed that feels right and at the spray rate of your equipment, then adjust your mix to equal xx amount of chemical into 30 gallons per acre.
For my purposes, chemical spray is cheaper than my time. Since you're only spraying 10 acres I would think the same applies. For that reason, I always mix spray concentrations on the high end to make up for my lack of precision in equipment, speed control, etc.
This will only cost you about a 1/2 hour of your time. Fill up your sprayer with water and go spray an acre. Don't worry about speed. Just drive it like it feels right and note your range setting, gear setting, etc. Note how much water it takes to cover an acre. The rest is easy.
