Actually, it depends on the chemical form of the nitrogen as to whether it is volatile or not. The common 34-0-0 nitrogen fertilizer is ammonium nitrate, and when it dissolves with the soil moisture releases ammonia (which is very volatile) and essentially nitric acid, which is not quite as volatile as ammonia but will still escape. "Slow release" forms of nitrogen are usually urea or some other similar chemical which is not volatile at all, but it will also take much longer to be released for the plants to use. Also realize that you are going to lower the pH of your soil if you apply heavily or on a regular basis, so you will probably need to increase your lime application if you use it more than very occasionally.