Agrotain is a liquid urease inhibitor that can be impregnated onto dry urea or tank mixed with liquid fertilizer that contains urea such as urea-ammonium nitrate (UAN).The active ingredient is N-(n-butyl) thiophosphoric triamide (NBPT). Agrotain Plus is a dry concentrate nitrogen stabilizer.It contains the urease inhibitor NBPT and dicyandiamide, a nitrogen stabilizer. When added to UAN, it minimizes volatilization, denitrification, and leaching of nitrogen for the urea portion of UAN.hat's where the urease inhibitor Agrotain comes in. Agrotain stops the activity of the urease enzyme for up to 14 days. If the urea is incorporated by tillage, rain, or irrigation during that period, losses should be minimal. Agrotain typically costs $50 to $55 per gallon.