At the moment, nitrogen in the form of liquid is cheaper than granular. if liquid is sprayed in the heat, probably above 70 degrees, it will burn your grass . Also the urea portion of the liquid may volatize and be partially lost to the atmosphere if it doesn't rain within about 3 days of application.
Liquid of course requires a spray rig, usually your own. Typically the dealer will give you a 1000 gallon nurse tank to bring the liquid to your farm, then you put it in your spray rig. You also have to worry about the wind and calibrating your spray rig if you go liquid.
Personally, I use liquid in the fall and early spring on winter pastures but, I applied 8 tons of granular last week due to the warmer weather for coastal bermudas.
