Formulation for fertilizer additive concentrate

Abstract

Improved solvent systems for the formulation of N-alkyl thiophosphoric triamide urease inhibitors. These formulations enable the preparation of stable concentrated solutions of N-alkyl thiophosphoric triamides for storage, transportation, and eventual impregnation onto solid urea containing fertilizers and incorporation into liquid urea containing fertilizer compositions. These formulations are comprised primarily of a solvent selected from the group consisting of glycols and glycol derivatives. Optionally, in addition to the glycol base solvent, the formulations can contain a co-solvent selected from the group consisting of liquid amides, 2-pyrrolidone and N-alkyl 2-pyrrolidones, and/or a nonionic surfactant selected from the group consisting of alkylaryl polyether alcohols. The presence of the co-solvent and/or surfactant has been found to impart desirable properties to the formulations under certain conditions. N-alkyl thiophosphoric triamides have been known for some time to be effective inhibitors of the activity of urease enzymes, however, commercial use has been inhibited by the lack of an acceptable carrier. They are often thermally and hydrolytically unstable and difficult to handle. The use of the solvent systems offers many advantages including: (1) improved stability of the active ingredient urease inhibitor; (2) excellent solubility characteristics; (3) extremely low flammability and toxicity of the solvents; (4) excellent cold temperature storage and handling characteristics with the addition of the liquid amide co-solvent; and (5) good adsorption characteristics onto solid urea containing fertilizers and excellent miscibility with liquid urea containing fertilizer formulations.