Synergistic effect of inhibitors (allylthiourea and 1,2,4-triazole) on the activity of wheat soil urease to reduce nitrogen loss

Abstract

Urease is a nickel-dependent metalloenzyme that catalyzes the hydrolysis of urea, forming CO2 and ammonia. Urease activity in soil enables several microorganisms to utilize urea as their nitrogen source. Nitrogen loss from the soil not only reduces the yield and soil fertility, but also create adverse effects on the environment. This study investigates the combined inhibitory potential of allylthiourea +1,2,4-triazole blend on the activity of wheat soil urease and to overcome the loss of nitrogen. For this purpose, soil samples were collected from three different regions of Punjab, Pakistan, i.e., Faisalabad, Sheikhupura, and Gujranwala. The whole research work was divided into two phases. During the first phase, the effect of different inhibitors on the activity of wheat soil urease was determined. In the second phase, kinetic behavior of urease enzyme in the presence and absence of urease inhibitors was evaluated by varying several factors i.e., pH, temperature, incubation time, and substrate concentration. Results indicated a significant urease reduction after 8th-14th day of application of inhibitor’s blend. After 14 days, the effect of urease inhibitors began to decrease. Kinetic studies revealed the optimum activity of the blend around pH 6.8, temperature 35–45 ​°C and incubation time 30 ​min. The Lineweaver-Burk plot revealed that Km value increased while Vmax value significantly decreased after applying the blend because of the formation of urease inhibitor complex that further retards the formation of enzyme-substrate complex. The synergistic usage of allylthiourea and 1,2,4-triazole inhibitor’s blend can prolong the urea hydrolysis, ultimately increasing the effectiveness of fertilizers.