Li Qianqian1, Liu Xuejun1, Chen Xinping1, Zhang Fusuo1
Maize field experiments were conducted over two years at Quzhou site (Hebei Province, North China Plain) to investigate ammonia (NH3) volatilization from urea and from urea amended with 0.12% (w/w) Limus® (a new urease inhibitor). Grain yields and nitrogen (N) budgets of all N treatments were evaluated to investigate the effects of urea-N application rates and Limus during two summer maize seasons. Cumulative NH3 losses after two weeks for conventional urea ranged from 42 to 108 kg N ha-1 (20-57% of applied N), while the new urease inhibitor Limus significantly reduced NH3 losses by 65 to 90%. However, maize grain yields (9.5-10.1 t ha-1) were not significantly (P<0.05) increased by Limus compared to conventional urea without Limus (9.0-10.1 t ha-1). A clear increase in apparent N recovery efficiency (REN) with Limus (ranging from 11 to 17 percentage points during two consecutive maize seasons) compared to equal amounts of optimized urea-N. A further 20% reduction in urea N rate amended with Limus led to the same maize yield but substantially decreased NH3 losses and increased REN compared with optimized urea treatment. Our study also demonstrates the role of Limus in reducing NH3 losses and improving N use efficiency in maize production in the North China Plain.