Phosphorotriamidate urease inhibitors and urease inhibited urea based fertilizer compositions

An improved fertilizer composition comprising urea and/or one or more urea precursor compounds capable of forming urea when subjected to the use conditions of the composition, and a urease inhibiting effective amount of one or more of compounds of the formula:

• ##STR6## wherein:
• X is oxygen or sulfur;
• R.sub.1 is alkyl substituted with one or more nucleophilic substituents;
• R.sub.2 is R.sub.1, hydrogen or substituted or unsubstituted alkyl, cyloalkenyl, alkenyl, alkynyl, cycloalkyl, aralkyl, aryl or alkaryl wherein permissible substituents are one or more trihalomethyl, alkyl, halogen, phenoxy, phenyl, nitro, arylmercapto, cyano, amino, alkylamino, naphthoxy, dialkylamino, alkoxy, mercapto, alkylcarbonyl, arylcarbonyl, alkylmercapto, arylamino, diarylamino, alkoxycarbonyl, carboxy, or carbonamide;
• and
• R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are individually hydrogen or alkyl having from 1 to about 4 carbon atoms.

A method of inhibiting the urease catalyzed hydrolysis of urea at a situs which comprises applying to said situs a urease inhibiting effective amount of one or more phosphorotriamidate compounds of the formula:

• ##STR7## wherein:
• X is oxygen or sulfur;
• R.sub.1 is alkyl substituted with one or more nucleophilic, substituents;
• R.sub.2 is R.sub.1, hydrogen or substituted or unsubstituted alkyl, cycloalkenyl, alkenyl, alkynyl, cycloalkyl, aralkyl, aryl or alkaryl wherein permissible substituents are one or more trihalomethyl, alkyl, halogen, naphthoxy, phenoxy, phenyl, nitro, cyano, amino, alkylamino, arylmercapto, alkylmercapto, arylamino, diarylamino, dialkylamino, alkoxy, mercapto, alkylcarbonyl, arylcarbonyl, alkoxycarbonyl, carboxy, or carbonamide;
• and
• R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are individually hydrogen or alkyl having from 1 to 4 carbon atoms.