[Dynamic simulation of nitrogen application level effects on rice yield and optimization analysis of fertilizer supply in paddy field].

Abstract

Field and water tank plot experiments were conducted in Zhejiang Province in 1999 to determine the effects of nitrogen application amount and times on rice growth and yield, and rice growth simulation model ORYZA-0 and nitrogen management module were used to establish a modified nitrogen effect-rice growth model. The simulated results presented a higher positive relationship with the measured results. According to the simulated and measured results, 160 kg.hm-2 was the economic nitrogen application amount for two rice varieties production, and the nitrogen application strategies were: 1) < 100 kg.hm-2 nitrogen fertilizer should be applied within 35 days after transplanting; 2) when the nitrogen application level was between 100-200 kg.hm-2, it should be applied within 45 days after transplanting; 3) if the nitrogen application amount exceeded 200 kg.hm-2, it should be put into paddy field within 60 days after transplanting; 4) as the nitrogen application amount increased, the nitrogen supply at the later rice growth stage should be increased. As for the second cropping rice, the more times the nitrogen applied in the field, the more closeness the rice yield reached the APCUM curve(optimized nitrogen curve) suggested. But in real rice production, it is impossible for farmers to adopt more times of N applying, since labor and cost will increase. Based on the experimental parameters and real rice production situation, the reasonable nitrogen application under 160 kg.hm-2 levels for high yielding second cropping rice was split into 4 times with fraction 0.2:0.3:0.3:0.2 at 5, 20, 30, 40 days after transplanting. The rice yield could reach 5,916 kg.hm-2, resulted in a 3.12% increase as compared with the yield under actual fertilizer application amount and timing.