Urea Nitrogen mostly applied to soil surface from top.

That is why Urea turns into ammonium gas and vaporizes 30-50% in field , 80% in laboratories if the inhibitors are not used.

NBPT inhibitor in Fergrow Slow 46N delays Urea to turn into ammonium around 2 weeks so that it the plant can absorb it before it turns into gas

This increase the length of Nitrogen usage time.

Urea is used mostly in Corn, Cotton, Canola, Wheat and Barley. Farmers are always stressed about the irrigation and rain but this fertilizer prevents this stress and losses. It is better than normal Urea in hot and dry weathers, less irrigation and rain on alkaline soils, organic material poor soils, stubble burn fields.

It affects the yield around 10-20% during the time of 5-6 leaf till crest, if the plant does not have the Nitrogen stress.