Abstract:Using sulfur- and polymer-coated controlled release urea with a releasing period of 90 days as experimental materials, a pot experiment was conducted to study the effects of sulfur- and polymer-coated controlled release urea on yield and photosynthetic characteristics and nitrogen fertilizer efficiency of rice. Compared with the conventional urea, the controlled release urea significantly increases the grain yields by 15.1%–51.4%, and increases the nitrogen apparent efficiencies and nitrogen agronomic efficiencies by 63.3%–139.9% and 5.4–18.2 kg/kg, respectively. The controlled release urea could greatly improve the net photosynthetic rate in flat leaves of rice and enhance SPAD during the middle-late growth stages. Compared with the conventional urea split, the polymer-coated controlled release urea and the 70% sulfur-coated controlled release urea combined with 30% conventional urea markedly increase the grain yields by 7.9%–31.7%, and the nitrogen agronomic efficiencies and soil total N and available N are increased by 3.3–13.0 kg/kg and 2.2%–17.6% and 13.2%–22.0%, respectively, and the net photosynthetic rate in flat leaves at the middle-late growth stages are also significantly increased. The effect of the 100% polymer-coated controlled release urea is most important. Compared with the conventional urea and the conventional urea split, the polymer-coated controlled release urea could significantly increase nitrogen fertilizer physiological efficiency of rice. The polymer-coated controlled release urea produces better rice yield and has higher nitrogen fertilizer efficiency and effective photosynthetic characteristics, compared with the sulfur-coated controlled release urea.