Abstract:To explore the effects of reducing nitrogen (N) and phosphorus (P) fertilizers on rice yield and runoff losses of N and P in paddy fields, a field plot experiment with different fertilization was conducted from 2016 to 2017 in the rice-planting area of Maoli Lake, the yield of rice, the variation of N and P in surface water, the runoff losses of N and P, and the use efficiencies of N and P fertilizers were monitored and compared after fertilization during the rice-growing period. The results showed that the concentrations of TN, NH4+-N and TP in surface water of paddy field under the treatments of conventional fertilization (CF) and organic-substitution of 20% fertilizer-N (0.8FN+0.2ON) peaked rapidly after fertilization, and then gradually decreased. However, the treatments of controlled release fertilizer with reduced N reduced effectively the release rate of N, and its N loss in surface water was much lower than that of CF treatment, and TP loss under the treatment of reduced P fertilizer was lower than that of CF treatment. Compared with CF treatment, from 2016 to 2017, the treatments of 20% reducting controlled release fertilizer-N (0.8N) and 20% reducting controlled release-N fertilizer + calcium superphosphate-P (0.8NP) increased meanly the yield of rice by 5.55% and 3.22%, N accumulation by 19.01% and 13.66%, N fertilizer partial factor productivity by 31.94% and 28.83%, N fertilizer agronomic efficiency by 47.52% and 33.75%, N fertilizer recovery efficiency by 95.30% and 73.31%, repsectively. Compared with 0.8N treatment, 0.8NP treatment increased mean P fertilizer partial factor productivity of rice significantly by 22.08%. Compared with CF treatment, 0.8FN+0.2ON treatment reduced P accumulation and P fertilizer recovery efficiency by 11.14% and 36.04%, respectively. In conclusion, reducing controlled release N fertilizer and/or P fertilizer can not only ensure high and stable rice yield, but also effectively reduce the runoff losses of N and P at the initial stage of fertilization in rice field. The fertilization mode of reducing controlled-release N fertilizer can be adopted in order to save the cost of agricultural production and control the non-point source pollution.