The most I've put on cotton was 3 gallons 14-2-8 (K coming from potassium nitrate) from a plane with insecticide, no additional water. 

Out of a ground rig I usually run a gallon or two 13-0-0 in 3-5 total volume when spaying for bugs.  I just keep feeding the cotton every time I spray.  I've used some 11-37-0 if I felt I needed some P, up to a gallon per acre with the 13-0-0.

Free ammonia is what often does the burning.  I've used some AMS to get rid of it and it worked fine.  The above mentioned 14-2-8 was mixed with some phos acid to get some heat and to kill the ammonia.

Also, the time of day (sunlight) and heat will affect the amount of burn you get.  Best advice I can give is to mix a test batch and spray a small area.  You will see the burn in a day or two if you got your mix too strong.