The Development of Urease-coated Inhibitor Synergistic Urea and its Effect on Wheat Growth

The combination of urease inhibitors (HQ) and urea could improve crop yield and nitrogen use efficiency (NUE). However, fixation and degradation may occur when common inhibitors are applied directly to soil. Consequently, there is a clear need to develop a synergistic form of urea that can prolong the duration of the inhibitor. In this study, hydroquinone (HQ) particles were prepared by disc granulation technology and coated by resin coating technology. Then, we blended different coating ratios of HQ and urea to create five different forms of HQ synergistic urea: (1) common urea + 100% common HQ, (2) common urea + 100% resin-coated HQ, (3) common urea + 30% common HQ + 70% resin-coated HQ, (4) common urea + 70% common HQ + 30% resin-coated HQ, (5) common urea + 50% resin-coated HQ + 50% common HQ. Scanning electron microscopy (SEM) and hydrostatic release tests were then used to evaluate the microstructure of the membrane and the controlled release performance of the resin-coated HQ. In addition, culture and field experiments were performed to investigate the effects of synergistic urea on delaying the hydrolysis of urea and the effects of synergistic urea on wheat growth, yield and NUE. SEM and hydrostatic release tests at 25degree celsius revealed that the resin-coated HQ film was intact and that the coating could effectively control the dissolution of HQ over a period of 42 days. Soil culture experiments further showed that the addition of HQ effectively inhibited the hydrolysis of urea, and extended the period of hydrolysis from 10 to 30 days when compared with Urea treatment (U). When compared with U treatment, field experiments revealed that the yield of wheat under T4 (urea + 50% common HQ + 50% resin-coated HQ) had increased significantly by 12.32%, and that the NUE had increased by 12.3%. Therefore, T4 treatment could effectively inhibit urea hydrolysis during the early growth stage of wheat, delay the hydrolysis process of urea during the subsequent growth stage, prolong the activity of HQ, and enhance the ability to continuously supply nitrogen (N) to crops. Our analyses demonstrate that the combination of 50% coated HQ + 50% common HQ and urea could effectively inhibit the hydrolysis of urea during the early growth stage, delay the hydrolysis of urea in the subsequent growth stage, prolong the activity of HQ, enhance the capacity to provide a continuous supply of N to meet crop demand, and could significantly improve wheat growth, yield, NUE and soil nitrogen supply.