Inhibition of jack bean urease by phosphoric-and thiophosphorictriamides

Three phosphorictriamides and two thiophosphorictriamides were tested for their urease inhibitory activities by using jack bean urease in an enzyme assay. The phosphorictriamides were N-(n-butyl)phosphorictriamide (NBPTO), cyclohexylphosphorictriamide (CHPT) and phosphoryltriamide (PT), and the thiophosphorictriamides were N-(n-butyl)thiophosphorictriamide (NBPT) and thiophosphoryltriamide. The assay technique used provided a relatively quick assessment of the effectiveness of the compounds tested to inhibit jack bean urease. NBPTO was a more effective inhibitor of jack bean urease than CHPT and PT. The concentrations of NBPTO, CHPT and PT required for 50% inhibition under the conditions of the experiment were 0.2, 6 and 23 μm, respectively. Evaluation of these compounds at various concentration ranges showed NBPTO and CHPT to be promising urease inhibitors

Use of urease, algal inhibitors, and nitrification inhibitors to reduce nitrogen loss and increase the grain yield of flooded rice (Oryza sativa L.)

We studied the interacting effects on NH loss and grain yield of adding (1) urease inhibitors to retard the hydrolysis of urea (2) the algicide terbutryn to limit floodwater pH increases, and (3) CH (provided by wax-coated calcium carbide) to prevent NH oxidation. The algicide treatment maintained the floodwater pH values below 8 for the first 3 days after the urea application and depressed the maximum values below 8.5 on subsequent days. As a consequence, NH loss was significantly (