N-(n-Butyl)thiophosphoric triamide (NBPT) is the organophosphorus compound with the formula SP(NH2)2(NHC4H9).

[1] Regarding its chemical structure, the molecule features tetrahedral phosphorus bonded to sulfur and three amido groups.

NBPT functions as an inhibitor of the enzyme urease.

[2] Urease, pervasive in soil microorganisms, converts urea into ammonia, which is susceptible to volatilization if produced faster than it can be utilized by plants.

Approximately 0.5% by weight NBPT is mixed with the urea.